Daniel Petre reported crashes in icmp_dst_unreach() with following call
graph:

#3 [ffff88003fc03938] __stack_chk_fail at ffffffff81037f77
#4 [ffff88003fc03948] icmp_send at ffffffff814d5fec
#5 [ffff88003fc03ae8] ipv4_link_failure at ffffffff814a1795
#6 [ffff88003fc03af8] ipgre_tunnel_xmit at ffffffff814e7965
#7 [ffff88003fc03b78] dev_hard_start_xmit at ffffffff8146e032
#8 [ffff88003fc03bc8] sch_direct_xmit at ffffffff81487d66
#9 [ffff88003fc03c08] __qdisc_run at ffffffff81487efd
#10 [ffff88003fc03c48] dev_queue_xmit at ffffffff8146e5a7
#11 [ffff88003fc03c88] ip_finish_output at ffffffff814ab596

Daniel found a similar problem mentioned in
 http://lkml.indiana.edu/hypermail/linux/kernel/1007.0/00961.html

And indeed this is the root cause : skb->cb[] contains data fooling IP
stack.

We must clear IPCB in ip_tunnel_xmit() sooner in case dst_link_failure()
is called. Or else skb->cb[] might contain garbage from GSO segmentation
layer.

A similar fix was tested on linux-3.9, but gre code was refactored in
linux-3.10. I'll send patches for stable kernels as well.

Many thanks to Daniel for providing reports, patches and testing !

Reported-by: Daniel Petre <daniel.petre@rcs-rds.ro>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

…/kernel/git/vgupta/arc

Pull first batch of ARC changes from Vineet Gupta:
 "There's a second bunch to follow next week - which depends on commits
  on other trees (irq/net).  I'd have preferred the accompanying ARC
  change via respective trees, but it didn't workout somehow.

  Highlights of changes:

   - Continuation of ARC MM changes from 3.10 including

       zero page optimization
       Setting pagecache pages dirty by default
       Non executable stack by default
       Reducing dcache flushes for aliasing VIPT config

   - Long overdue rework of pt_regs machinery - removing the unused word
     gutters and adding ECR register to baseline (helps cleanup lot of
     low level code)

   - Support for ARC gcc 4.8

   - Few other preventive fixes, cosmetics, usage of Kconfig helper..

  The diffstat is larger than normal primarily because of arcregs.h
  header split as well as beautification of macros in entry.h"

* tag 'arc-v3.11-rc1-part1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc: (32 commits)
  ARC: warn on improper stack unwind FDE entries
  arc: delete __cpuinit usage from all arc files
  ARC: [tlb-miss] Fix bug with CONFIG_ARC_DBG_TLB_MISS_COUNT
  ARC: [tlb-miss] Extraneous PTE bit testing/setting
  ARC: Adjustments for gcc 4.8
  ARC: Setup Vector Table Base in early boot
  ARC: Remove explicit passing around of ECR
  ARC: pt_regs update #5: Use real ECR for pt_regs->event vs. synth values
  ARC: stop using pt_regs->orig_r8
  ARC: pt_regs update #4: r25 saved/restored unconditionally
  ARC: K/U SP saved from one location in stack switching macro
  ARC: Entry Handler tweaks: Simplify branch for in-kernel preemption
  ARC: Entry Handler tweaks: Avoid hardcoded LIMMS for ECR values
  ARC: Increase readability of entry handlers
  ARC: pt_regs update #3: Remove unused gutter at start of callee_regs
  ARC: pt_regs update #2: Remove unused gutter at start of pt_regs
  ARC: pt_regs update #1: Align pt_regs end with end of kernel stack page
  ARC: pt_regs update #0: remove kernel stack canary
  ARC: [mm] Remove @Write argument to do_page_fault()
  ARC: [mm] Make stack/heap Non-executable by default
  ...

commit 2f7021a "cpufreq: protect 'policy->cpus' from offlining
during __gov_queue_work()" caused a regression in CPU hotplug,
because it lead to a deadlock between cpufreq governor worker thread
and the CPU hotplug writer task.

Lockdep splat corresponding to this deadlock is shown below:

[   60.277396] ======================================================
[   60.277400] [ INFO: possible circular locking dependency detected ]
[   60.277407] 3.10.0-rc7-dbg-01385-g241fd04-dirty #1744 Not tainted
[   60.277411] -------------------------------------------------------
[   60.277417] bash/2225 is trying to acquire lock:
[   60.277422]  ((&(&j_cdbs->work)->work)){+.+...}, at: [<ffffffff810621b5>] flush_work+0x5/0x280
[   60.277444] but task is already holding lock:
[   60.277449]  (cpu_hotplug.lock){+.+.+.}, at: [<ffffffff81042d8b>] cpu_hotplug_begin+0x2b/0x60
[   60.277465] which lock already depends on the new lock.

[   60.277472] the existing dependency chain (in reverse order) is:
[   60.277477] -> #2 (cpu_hotplug.lock){+.+.+.}:
[   60.277490]        [<ffffffff810ac6d4>] lock_acquire+0xa4/0x200
[   60.277503]        [<ffffffff815b6157>] mutex_lock_nested+0x67/0x410
[   60.277514]        [<ffffffff81042cbc>] get_online_cpus+0x3c/0x60
[   60.277522]        [<ffffffff814b842a>] gov_queue_work+0x2a/0xb0
[   60.277532]        [<ffffffff814b7891>] cs_dbs_timer+0xc1/0xe0
[   60.277543]        [<ffffffff8106302d>] process_one_work+0x1cd/0x6a0
[   60.277552]        [<ffffffff81063d31>] worker_thread+0x121/0x3a0
[   60.277560]        [<ffffffff8106ae2b>] kthread+0xdb/0xe0
[   60.277569]        [<ffffffff815bb96c>] ret_from_fork+0x7c/0xb0
[   60.277580] -> #1 (&j_cdbs->timer_mutex){+.+...}:
[   60.277592]        [<ffffffff810ac6d4>] lock_acquire+0xa4/0x200
[   60.277600]        [<ffffffff815b6157>] mutex_lock_nested+0x67/0x410
[   60.277608]        [<ffffffff814b785d>] cs_dbs_timer+0x8d/0xe0
[   60.277616]        [<ffffffff8106302d>] process_one_work+0x1cd/0x6a0
[   60.277624]        [<ffffffff81063d31>] worker_thread+0x121/0x3a0
[   60.277633]        [<ffffffff8106ae2b>] kthread+0xdb/0xe0
[   60.277640]        [<ffffffff815bb96c>] ret_from_fork+0x7c/0xb0
[   60.277649] -> #0 ((&(&j_cdbs->work)->work)){+.+...}:
[   60.277661]        [<ffffffff810ab826>] __lock_acquire+0x1766/0x1d30
[   60.277669]        [<ffffffff810ac6d4>] lock_acquire+0xa4/0x200
[   60.277677]        [<ffffffff810621ed>] flush_work+0x3d/0x280
[   60.277685]        [<ffffffff81062d8a>] __cancel_work_timer+0x8a/0x120
[   60.277693]        [<ffffffff81062e53>] cancel_delayed_work_sync+0x13/0x20
[   60.277701]        [<ffffffff814b89d9>] cpufreq_governor_dbs+0x529/0x6f0
[   60.277709]        [<ffffffff814b76a7>] cs_cpufreq_governor_dbs+0x17/0x20
[   60.277719]        [<ffffffff814b5df8>] __cpufreq_governor+0x48/0x100
[   60.277728]        [<ffffffff814b6b80>] __cpufreq_remove_dev.isra.14+0x80/0x3c0
[   60.277737]        [<ffffffff815adc0d>] cpufreq_cpu_callback+0x38/0x4c
[   60.277747]        [<ffffffff81071a4d>] notifier_call_chain+0x5d/0x110
[   60.277759]        [<ffffffff81071b0e>] __raw_notifier_call_chain+0xe/0x10
[   60.277768]        [<ffffffff815a0a68>] _cpu_down+0x88/0x330
[   60.277779]        [<ffffffff815a0d46>] cpu_down+0x36/0x50
[   60.277788]        [<ffffffff815a2748>] store_online+0x98/0xd0
[   60.277796]        [<ffffffff81452a28>] dev_attr_store+0x18/0x30
[   60.277806]        [<ffffffff811d9edb>] sysfs_write_file+0xdb/0x150
[   60.277818]        [<ffffffff8116806d>] vfs_write+0xbd/0x1f0
[   60.277826]        [<ffffffff811686fc>] SyS_write+0x4c/0xa0
[   60.277834]        [<ffffffff815bbbbe>] tracesys+0xd0/0xd5
[   60.277842] other info that might help us debug this:

[   60.277848] Chain exists of:
  (&(&j_cdbs->work)->work) --> &j_cdbs->timer_mutex --> cpu_hotplug.lock

[   60.277864]  Possible unsafe locking scenario:

[   60.277869]        CPU0                    CPU1
[   60.277873]        ----                    ----
[   60.277877]   lock(cpu_hotplug.lock);
[   60.277885]                                lock(&j_cdbs->timer_mutex);
[   60.277892]                                lock(cpu_hotplug.lock);
[   60.277900]   lock((&(&j_cdbs->work)->work));
[   60.277907]  *** DEADLOCK ***

[   60.277915] 6 locks held by bash/2225:
[   60.277919]  #0:  (sb_writers#6){.+.+.+}, at: [<ffffffff81168173>] vfs_write+0x1c3/0x1f0
[   60.277937]  #1:  (&buffer->mutex){+.+.+.}, at: [<ffffffff811d9e3c>] sysfs_write_file+0x3c/0x150
[   60.277954]  #2:  (s_active#61){.+.+.+}, at: [<ffffffff811d9ec3>] sysfs_write_file+0xc3/0x150
[   60.277972]  #3:  (x86_cpu_hotplug_driver_mutex){+.+...}, at: [<ffffffff81024cf7>] cpu_hotplug_driver_lock+0x17/0x20
[   60.277990]  #4:  (cpu_add_remove_lock){+.+.+.}, at: [<ffffffff815a0d32>] cpu_down+0x22/0x50
[   60.278007]  #5:  (cpu_hotplug.lock){+.+.+.}, at: [<ffffffff81042d8b>] cpu_hotplug_begin+0x2b/0x60
[   60.278023] stack backtrace:
[   60.278031] CPU: 3 PID: 2225 Comm: bash Not tainted 3.10.0-rc7-dbg-01385-g241fd04-dirty #1744
[   60.278037] Hardware name: Acer             Aspire 5741G    /Aspire 5741G    , BIOS V1.20 02/08/2011
[   60.278042]  ffffffff8204e110 ffff88014df6b9f8 ffffffff815b3d90 ffff88014df6ba38
[   60.278055]  ffffffff815b0a8d ffff880150ed3f60 ffff880150ed4770 3871c4002c8980b2
[   60.278068]  ffff880150ed4748 ffff880150ed4770 ffff880150ed3f60 ffff88014df6bb00
[   60.278081] Call Trace:
[   60.278091]  [<ffffffff815b3d90>] dump_stack+0x19/0x1b
[   60.278101]  [<ffffffff815b0a8d>] print_circular_bug+0x2b6/0x2c5
[   60.278111]  [<ffffffff810ab826>] __lock_acquire+0x1766/0x1d30
[   60.278123]  [<ffffffff81067e08>] ? __kernel_text_address+0x58/0x80
[   60.278134]  [<ffffffff810ac6d4>] lock_acquire+0xa4/0x200
[   60.278142]  [<ffffffff810621b5>] ? flush_work+0x5/0x280
[   60.278151]  [<ffffffff810621ed>] flush_work+0x3d/0x280
[   60.278159]  [<ffffffff810621b5>] ? flush_work+0x5/0x280
[   60.278169]  [<ffffffff810a9b14>] ? mark_held_locks+0x94/0x140
[   60.278178]  [<ffffffff81062d77>] ? __cancel_work_timer+0x77/0x120
[   60.278188]  [<ffffffff810a9cbd>] ? trace_hardirqs_on_caller+0xfd/0x1c0
[   60.278196]  [<ffffffff81062d8a>] __cancel_work_timer+0x8a/0x120
[   60.278206]  [<ffffffff81062e53>] cancel_delayed_work_sync+0x13/0x20
[   60.278214]  [<ffffffff814b89d9>] cpufreq_governor_dbs+0x529/0x6f0
[   60.278225]  [<ffffffff814b76a7>] cs_cpufreq_governor_dbs+0x17/0x20
[   60.278234]  [<ffffffff814b5df8>] __cpufreq_governor+0x48/0x100
[   60.278244]  [<ffffffff814b6b80>] __cpufreq_remove_dev.isra.14+0x80/0x3c0
[   60.278255]  [<ffffffff815adc0d>] cpufreq_cpu_callback+0x38/0x4c
[   60.278265]  [<ffffffff81071a4d>] notifier_call_chain+0x5d/0x110
[   60.278275]  [<ffffffff81071b0e>] __raw_notifier_call_chain+0xe/0x10
[   60.278284]  [<ffffffff815a0a68>] _cpu_down+0x88/0x330
[   60.278292]  [<ffffffff81024cf7>] ? cpu_hotplug_driver_lock+0x17/0x20
[   60.278302]  [<ffffffff815a0d46>] cpu_down+0x36/0x50
[   60.278311]  [<ffffffff815a2748>] store_online+0x98/0xd0
[   60.278320]  [<ffffffff81452a28>] dev_attr_store+0x18/0x30
[   60.278329]  [<ffffffff811d9edb>] sysfs_write_file+0xdb/0x150
[   60.278337]  [<ffffffff8116806d>] vfs_write+0xbd/0x1f0
[   60.278347]  [<ffffffff81185950>] ? fget_light+0x320/0x4b0
[   60.278355]  [<ffffffff811686fc>] SyS_write+0x4c/0xa0
[   60.278364]  [<ffffffff815bbbbe>] tracesys+0xd0/0xd5
[   60.280582] smpboot: CPU 1 is now offline

The intention of that commit was to avoid warnings during CPU
hotplug, which indicated that offline CPUs were getting IPIs from the
cpufreq governor's work items.  But the real root-cause of that
problem was commit a66b2e5 (cpufreq: Preserve sysfs files across
suspend/resume) because it totally skipped all the cpufreq callbacks
during CPU hotplug in the suspend/resume path, and hence it never
actually shut down the cpufreq governor's worker threads during CPU
offline in the suspend/resume path.

Reflecting back, the reason why we never suspected that commit as the
root-cause earlier, was that the original issue was reported with
just the halt command and nobody had brought in suspend/resume to the
equation.

The reason for _that_ in turn, as it turns out, is that earlier
halt/shutdown was being done by disabling non-boot CPUs while tasks
were frozen, just like suspend/resume....  but commit cf7df37
(reboot: migrate shutdown/reboot to boot cpu) which came somewhere
along that very same time changed that logic: shutdown/halt no longer
takes CPUs offline.  Thus, the test-cases for reproducing the bug
were vastly different and thus we went totally off the trail.

Overall, it was one hell of a confusion with so many commits
affecting each other and also affecting the symptoms of the problems
in subtle ways.  Finally, now since the original problematic commit
(a66b2e5) has been completely reverted, revert this intermediate fix
too (2f7021a), to fix the CPU hotplug deadlock.  Phew!

Reported-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reported-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Tested-by: Peter Wu <lekensteyn@gmail.com>
Cc: 3.10+ <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Commits 6a1c068 and
9356b53, respectively
  'tty: Convert termios_mutex to termios_rwsem' and
  'n_tty: Access termios values safely'
introduced a circular lock dependency with console_lock and
termios_rwsem.

The lockdep report [1] shows that n_tty_write() will attempt
to claim console_lock while holding the termios_rwsem, whereas
tty_do_resize() may already hold the console_lock while
claiming the termios_rwsem.

Since n_tty_write() and tty_do_resize() do not contend
over the same data -- the tty->winsize structure -- correct
the lock dependency by introducing a new lock which
specifically serializes access to tty->winsize only.

[1] Lockdep report

======================================================
[ INFO: possible circular locking dependency detected ]
3.10.0-0+tip-xeon+lockdep #0+tip Not tainted
-------------------------------------------------------
modprobe/277 is trying to acquire lock:
 (&tty->termios_rwsem){++++..}, at: [<ffffffff81452656>] tty_do_resize+0x36/0xe0

but task is already holding lock:
 ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 ((fb_notifier_list).rwsem){.+.+.+}:
       [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0
       [<ffffffff8175b797>] down_read+0x47/0x5c
       [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0
       [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20
       [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20
       [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320
       [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper]
       [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau]
       [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau]
       [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm]
       [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau]
       [<ffffffff813b13db>] local_pci_probe+0x4b/0x80
       [<ffffffff813b1701>] pci_device_probe+0x111/0x120
       [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0
       [<ffffffff81497bab>] __driver_attach+0xab/0xb0
       [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0
       [<ffffffff814971fe>] driver_attach+0x1e/0x20
       [<ffffffff81496cc1>] bus_add_driver+0x111/0x290
       [<ffffffff814982b7>] driver_register+0x77/0x170
       [<ffffffff813b0454>] __pci_register_driver+0x64/0x70
       [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm]
       [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau]
       [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0
       [<ffffffff810c54cb>] load_module+0x123b/0x1bf0
       [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120
       [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b

-> #1 (console_lock){+.+.+.}:
       [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0
       [<ffffffff810430a7>] console_lock+0x77/0x80
       [<ffffffff8146b2a1>] con_flush_chars+0x31/0x50
       [<ffffffff8145780c>] n_tty_write+0x1ec/0x4d0
       [<ffffffff814541b9>] tty_write+0x159/0x2e0
       [<ffffffff814543f5>] redirected_tty_write+0xb5/0xc0
       [<ffffffff811ab9d5>] vfs_write+0xc5/0x1f0
       [<ffffffff811abec5>] SyS_write+0x55/0xa0
       [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b

-> #0 (&tty->termios_rwsem){++++..}:
       [<ffffffff810b65c3>] __lock_acquire+0x1c43/0x1d30
       [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0
       [<ffffffff8175b724>] down_write+0x44/0x70
       [<ffffffff81452656>] tty_do_resize+0x36/0xe0
       [<ffffffff8146c841>] vc_do_resize+0x3e1/0x4c0
       [<ffffffff8146c99f>] vc_resize+0x1f/0x30
       [<ffffffff813e4535>] fbcon_init+0x385/0x5a0
       [<ffffffff8146a4bc>] visual_init+0xbc/0x120
       [<ffffffff8146cd13>] do_bind_con_driver+0x163/0x320
       [<ffffffff8146cfa1>] do_take_over_console+0x61/0x70
       [<ffffffff813e2b93>] do_fbcon_takeover+0x63/0xc0
       [<ffffffff813e67a5>] fbcon_event_notify+0x715/0x820
       [<ffffffff81762f9d>] notifier_call_chain+0x5d/0x110
       [<ffffffff8107aadc>] __blocking_notifier_call_chain+0x6c/0xc0
       [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20
       [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20
       [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320
       [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper]
       [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau]
       [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau]
       [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm]
       [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau]
       [<ffffffff813b13db>] local_pci_probe+0x4b/0x80
       [<ffffffff813b1701>] pci_device_probe+0x111/0x120
       [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0
       [<ffffffff81497bab>] __driver_attach+0xab/0xb0
       [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0
       [<ffffffff814971fe>] driver_attach+0x1e/0x20
       [<ffffffff81496cc1>] bus_add_driver+0x111/0x290
       [<ffffffff814982b7>] driver_register+0x77/0x170
       [<ffffffff813b0454>] __pci_register_driver+0x64/0x70
       [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm]
       [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau]
       [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0
       [<ffffffff810c54cb>] load_module+0x123b/0x1bf0
       [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120
       [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b

other info that might help us debug this:

Chain exists of:
  &tty->termios_rwsem --> console_lock --> (fb_notifier_list).rwsem

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock((fb_notifier_list).rwsem);
                               lock(console_lock);
                               lock((fb_notifier_list).rwsem);
  lock(&tty->termios_rwsem);

 *** DEADLOCK ***

7 locks held by modprobe/277:
 #0:  (&__lockdep_no_validate__){......}, at: [<ffffffff81497b5b>] __driver_attach+0x5b/0xb0
 #1:  (&__lockdep_no_validate__){......}, at: [<ffffffff81497b69>] __driver_attach+0x69/0xb0
 #2:  (drm_global_mutex){+.+.+.}, at: [<ffffffffa008a6dd>] drm_get_pci_dev+0xbd/0x2a0 [drm]
 #3:  (registration_lock){+.+.+.}, at: [<ffffffff813d93f5>] register_framebuffer+0x25/0x320
 #4:  (&fb_info->lock){+.+.+.}, at: [<ffffffff813d8116>] lock_fb_info+0x26/0x60
 #5:  (console_lock){+.+.+.}, at: [<ffffffff813d95a4>] register_framebuffer+0x1d4/0x320
 #6:  ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff8107aac6>] __blocking_notifier_call_chain+0x56/0xc0

stack backtrace:
CPU: 0 PID: 277 Comm: modprobe Not tainted 3.10.0-0+tip-xeon+lockdep #0+tip
Hardware name: Dell Inc. Precision WorkStation T5400  /0RW203, BIOS A11 04/30/2012
 ffffffff8213e5e0 ffff8802aa2fb298 ffffffff81755f19 ffff8802aa2fb2e8
 ffffffff8174f506 ffff8802aa2fa000 ffff8802aa2fb378 ffff8802aa2ea8e8
 ffff8802aa2ea910 ffff8802aa2ea8e8 0000000000000006 0000000000000007
Call Trace:
 [<ffffffff81755f19>] dump_stack+0x19/0x1b
 [<ffffffff8174f506>] print_circular_bug+0x1fb/0x20c
 [<ffffffff810b65c3>] __lock_acquire+0x1c43/0x1d30
 [<ffffffff810b775e>] ? mark_held_locks+0xae/0x120
 [<ffffffff810b78d5>] ? trace_hardirqs_on_caller+0x105/0x1d0
 [<ffffffff810b6d62>] lock_acquire+0x92/0x1f0
 [<ffffffff81452656>] ? tty_do_resize+0x36/0xe0
 [<ffffffff8175b724>] down_write+0x44/0x70
 [<ffffffff81452656>] ? tty_do_resize+0x36/0xe0
 [<ffffffff81452656>] tty_do_resize+0x36/0xe0
 [<ffffffff8146c841>] vc_do_resize+0x3e1/0x4c0
 [<ffffffff8146c99f>] vc_resize+0x1f/0x30
 [<ffffffff813e4535>] fbcon_init+0x385/0x5a0
 [<ffffffff8146a4bc>] visual_init+0xbc/0x120
 [<ffffffff8146cd13>] do_bind_con_driver+0x163/0x320
 [<ffffffff8146cfa1>] do_take_over_console+0x61/0x70
 [<ffffffff813e2b93>] do_fbcon_takeover+0x63/0xc0
 [<ffffffff813e67a5>] fbcon_event_notify+0x715/0x820
 [<ffffffff81762f9d>] notifier_call_chain+0x5d/0x110
 [<ffffffff8107aadc>] __blocking_notifier_call_chain+0x6c/0xc0
 [<ffffffff8107ab46>] blocking_notifier_call_chain+0x16/0x20
 [<ffffffff813d7c0b>] fb_notifier_call_chain+0x1b/0x20
 [<ffffffff813d95b2>] register_framebuffer+0x1e2/0x320
 [<ffffffffa01043e1>] drm_fb_helper_initial_config+0x371/0x540 [drm_kms_helper]
 [<ffffffff8173cbcb>] ? kmemleak_alloc+0x5b/0xc0
 [<ffffffff81198874>] ? kmem_cache_alloc_trace+0x104/0x290
 [<ffffffffa01035e1>] ? drm_fb_helper_single_add_all_connectors+0x81/0xf0 [drm_kms_helper]
 [<ffffffffa01bcb05>] nouveau_fbcon_init+0x105/0x140 [nouveau]
 [<ffffffffa01ad0af>] nouveau_drm_load+0x43f/0x610 [nouveau]
 [<ffffffffa008a79e>] drm_get_pci_dev+0x17e/0x2a0 [drm]
 [<ffffffffa01ad4da>] nouveau_drm_probe+0x25a/0x2a0 [nouveau]
 [<ffffffff8175f162>] ? _raw_spin_unlock_irqrestore+0x42/0x80
 [<ffffffff813b13db>] local_pci_probe+0x4b/0x80
 [<ffffffff813b1701>] pci_device_probe+0x111/0x120
 [<ffffffff814977eb>] driver_probe_device+0x8b/0x3a0
 [<ffffffff81497bab>] __driver_attach+0xab/0xb0
 [<ffffffff81497b00>] ? driver_probe_device+0x3a0/0x3a0
 [<ffffffff814956ad>] bus_for_each_dev+0x5d/0xa0
 [<ffffffff814971fe>] driver_attach+0x1e/0x20
 [<ffffffff81496cc1>] bus_add_driver+0x111/0x290
 [<ffffffffa022a000>] ? 0xffffffffa0229fff
 [<ffffffff814982b7>] driver_register+0x77/0x170
 [<ffffffffa022a000>] ? 0xffffffffa0229fff
 [<ffffffff813b0454>] __pci_register_driver+0x64/0x70
 [<ffffffffa008a9da>] drm_pci_init+0x11a/0x130 [drm]
 [<ffffffffa022a000>] ? 0xffffffffa0229fff
 [<ffffffffa022a000>] ? 0xffffffffa0229fff
 [<ffffffffa022a04d>] nouveau_drm_init+0x4d/0x1000 [nouveau]
 [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0
 [<ffffffff810c54cb>] load_module+0x123b/0x1bf0
 [<ffffffff81399a50>] ? ddebug_proc_open+0xb0/0xb0
 [<ffffffff813855ae>] ? trace_hardirqs_on_thunk+0x3a/0x3f
 [<ffffffff810c5f57>] SyS_init_module+0xd7/0x120
 [<ffffffff817677c2>] system_call_fastpath+0x16/0x1b

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

We used to keep the port's char device structs and the /sys entries
around till the last reference to the port was dropped.  This is
actually unnecessary, and resulted in buggy behaviour:

1. Open port in guest
2. Hot-unplug port
3. Hot-plug a port with the same 'name' property as the unplugged one

This resulted in hot-plug being unsuccessful, as a port with the same
name already exists (even though it was unplugged).

This behaviour resulted in a warning message like this one:

-------------------8<---------------------------------------
WARNING: at fs/sysfs/dir.c:512 sysfs_add_one+0xc9/0x130() (Not tainted)
Hardware name: KVM
sysfs: cannot create duplicate filename
'/devices/pci0000:00/0000:00:04.0/virtio0/virtio-ports/vport0p1'

Call Trace:
 [<ffffffff8106b607>] ? warn_slowpath_common+0x87/0xc0
 [<ffffffff8106b6f6>] ? warn_slowpath_fmt+0x46/0x50
 [<ffffffff811f2319>] ? sysfs_add_one+0xc9/0x130
 [<ffffffff811f23e8>] ? create_dir+0x68/0xb0
 [<ffffffff811f2469>] ? sysfs_create_dir+0x39/0x50
 [<ffffffff81273129>] ? kobject_add_internal+0xb9/0x260
 [<ffffffff812733d8>] ? kobject_add_varg+0x38/0x60
 [<ffffffff812734b4>] ? kobject_add+0x44/0x70
 [<ffffffff81349de4>] ? get_device_parent+0xf4/0x1d0
 [<ffffffff8134b389>] ? device_add+0xc9/0x650

-------------------8<---------------------------------------

Instead of relying on guest applications to release all references to
the ports, we should go ahead and unregister the port from all the core
layers.  Any open/read calls on the port will then just return errors,
and an unplug/plug operation on the host will succeed as expected.

This also caused buggy behaviour in case of the device removal (not just
a port): when the device was removed (which means all ports on that
device are removed automatically as well), the ports with active
users would clean up only when the last references were dropped -- and
it would be too late then to be referencing char device pointers,
resulting in oopses:

-------------------8<---------------------------------------
PID: 6162   TASK: ffff8801147ad500  CPU: 0   COMMAND: "cat"
 #0 [ffff88011b9d5a90] machine_kexec at ffffffff8103232b
 #1 [ffff88011b9d5af0] crash_kexec at ffffffff810b9322
 #2 [ffff88011b9d5bc0] oops_end at ffffffff814f4a50
 #3 [ffff88011b9d5bf0] die at ffffffff8100f26b
 #4 [ffff88011b9d5c20] do_general_protection at ffffffff814f45e2
 #5 [ffff88011b9d5c50] general_protection at ffffffff814f3db5
    [exception RIP: strlen+2]
    RIP: ffffffff81272ae2  RSP: ffff88011b9d5d00  RFLAGS: 00010246
    RAX: 0000000000000000  RBX: ffff880118901c18  RCX: 0000000000000000
    RDX: ffff88011799982c  RSI: 00000000000000d0  RDI: 3a303030302f3030
    RBP: ffff88011b9d5d38   R8: 0000000000000006   R9: ffffffffa0134500
    R10: 0000000000001000  R11: 0000000000001000  R12: ffff880117a1cc10
    R13: 00000000000000d0  R14: 0000000000000017  R15: ffffffff81aff700
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 #6 [ffff88011b9d5d00] kobject_get_path at ffffffff8126dc5d
 #7 [ffff88011b9d5d40] kobject_uevent_env at ffffffff8126e551
 #8 [ffff88011b9d5dd0] kobject_uevent at ffffffff8126e9eb
 #9 [ffff88011b9d5de0] device_del at ffffffff813440c7

-------------------8<---------------------------------------

So clean up when we have all the context, and all that's left to do when
the references to the port have dropped is to free up the port struct
itself.

CC: <stable@vger.kernel.org>
Reported-by: chayang <chayang@redhat.com>
Reported-by: YOGANANTH SUBRAMANIAN <anantyog@in.ibm.com>
Reported-by: FuXiangChun <xfu@redhat.com>
Reported-by: Qunfang Zhang <qzhang@redhat.com>
Reported-by: Sibiao Luo <sluo@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

This fixes the following hard lockup in isolate_lru_folios() during memory
reclaim.  If the LRU mostly contains ineligible folios this may trigger
watchdog.

watchdog: Watchdog detected hard LOCKUP on cpu 173
RIP: 0010:native_queued_spin_lock_slowpath+0x255/0x2a0
Call Trace:
	_raw_spin_lock_irqsave+0x31/0x40
	folio_lruvec_lock_irqsave+0x5f/0x90
	folio_batch_move_lru+0x91/0x150
	lru_add_drain_per_cpu+0x1c/0x40
	process_one_work+0x17d/0x350
	worker_thread+0x27b/0x3a0
	kthread+0xe8/0x120
	ret_from_fork+0x34/0x50
	ret_from_fork_asm+0x1b/0x30

lruvec->lru_lock owner：

PID: 2865     TASK: ffff888139214d40  CPU: 40   COMMAND: "kswapd0"
 #0 [fffffe0000945e60] crash_nmi_callback at ffffffffa567a555
 #1 [fffffe0000945e68] nmi_handle at ffffffffa563b171
 #2 [fffffe0000945eb0] default_do_nmi at ffffffffa6575920
 #3 [fffffe0000945ed0] exc_nmi at ffffffffa6575af4
 #4 [fffffe0000945ef0] end_repeat_nmi at ffffffffa6601dde
    [exception RIP: isolate_lru_folios+403]
    RIP: ffffffffa597df53  RSP: ffffc90006fb7c28  RFLAGS: 00000002
    RAX: 0000000000000001  RBX: ffffc90006fb7c60  RCX: ffffea04a2196f88
    RDX: ffffc90006fb7c60  RSI: ffffc90006fb7c60  RDI: ffffea04a2197048
    RBP: ffff88812cbd3010   R8: ffffea04a2197008   R9: 0000000000000001
    R10: 0000000000000000  R11: 0000000000000001  R12: ffffea04a2197008
    R13: ffffea04a2197048  R14: ffffc90006fb7de8  R15: 0000000003e3e937
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
    <NMI exception stack>
 #5 [ffffc90006fb7c28] isolate_lru_folios at ffffffffa597df53
 #6 [ffffc90006fb7cf8] shrink_active_list at ffffffffa597f788
 #7 [ffffc90006fb7da8] balance_pgdat at ffffffffa5986db0
 #8 [ffffc90006fb7ec0] kswapd at ffffffffa5987354
 #9 [ffffc90006fb7ef8] kthread at ffffffffa5748238
crash>

Scenario:
User processe are requesting a large amount of memory and keep page active.
Then a module continuously requests memory from ZONE_DMA32 area.
Memory reclaim will be triggered due to ZONE_DMA32 watermark alarm reached.
However pages in the LRU(active_anon) list are mostly from
the ZONE_NORMAL area.

Reproduce:
Terminal 1: Construct to continuously increase pages active(anon).
mkdir /tmp/memory
mount -t tmpfs -o size=1024000M tmpfs /tmp/memory
dd if=/dev/zero of=/tmp/memory/block bs=4M
tail /tmp/memory/block

Terminal 2:
vmstat -a 1
active will increase.
procs ---memory--- ---swap-- ---io---- -system-- ---cpu--- ...
 r  b   swpd   free  inact active   si   so    bi    bo
 1  0   0 1445623076 45898836 83646008    0    0     0
 1  0   0 1445623076 43450228 86094616    0    0     0
 1  0   0 1445623076 41003480 88541364    0    0     0
 1  0   0 1445623076 38557088 90987756    0    0     0
 1  0   0 1445623076 36109688 93435156    0    0     0
 1  0   0 1445619552 33663256 95881632    0    0     0
 1  0   0 1445619804 31217140 98327792    0    0     0
 1  0   0 1445619804 28769988 100774944    0    0     0
 1  0   0 1445619804 26322348 103222584    0    0     0
 1  0   0 1445619804 23875592 105669340    0    0     0

cat /proc/meminfo | head
Active(anon) increase.
MemTotal:       1579941036 kB
MemFree:        1445618500 kB
MemAvailable:   1453013224 kB
Buffers:            6516 kB
Cached:         128653956 kB
SwapCached:            0 kB
Active:         118110812 kB
Inactive:       11436620 kB
Active(anon):   115345744 kB
Inactive(anon):   945292 kB

When the Active(anon) is 115345744 kB, insmod module triggers
the ZONE_DMA32 watermark.

perf record -e vmscan:mm_vmscan_lru_isolate -aR
perf script
isolate_mode=0 classzone=1 order=1 nr_requested=32 nr_scanned=2
nr_skipped=2 nr_taken=0 lru=active_anon
isolate_mode=0 classzone=1 order=1 nr_requested=32 nr_scanned=0
nr_skipped=0 nr_taken=0 lru=active_anon
isolate_mode=0 classzone=1 order=0 nr_requested=32 nr_scanned=28835844
nr_skipped=28835844 nr_taken=0 lru=active_anon
isolate_mode=0 classzone=1 order=1 nr_requested=32 nr_scanned=28835844
nr_skipped=28835844 nr_taken=0 lru=active_anon
isolate_mode=0 classzone=1 order=0 nr_requested=32 nr_scanned=29
nr_skipped=29 nr_taken=0 lru=active_anon
isolate_mode=0 classzone=1 order=0 nr_requested=32 nr_scanned=0
nr_skipped=0 nr_taken=0 lru=active_anon

See nr_scanned=28835844.
28835844 * 4k = 115343376KB approximately equal to 115345744 kB.

If increase Active(anon) to 1000G then insmod module triggers
the ZONE_DMA32 watermark. hard lockup will occur.

In my device nr_scanned = 0000000003e3e937 when hard lockup.
Convert to memory size 0x0000000003e3e937 * 4KB = 261072092 KB.

   [ffffc90006fb7c28] isolate_lru_folios at ffffffffa597df53
    ffffc90006fb7c30: 0000000000000020 0000000000000000
    ffffc90006fb7c40: ffffc90006fb7d40 ffff88812cbd3000
    ffffc90006fb7c50: ffffc90006fb7d30 0000000106fb7de8
    ffffc90006fb7c60: ffffea04a2197008 ffffea0006ed4a48
    ffffc90006fb7c70: 0000000000000000 0000000000000000
    ffffc90006fb7c80: 0000000000000000 0000000000000000
    ffffc90006fb7c90: 0000000000000000 0000000000000000
    ffffc90006fb7ca0: 0000000000000000 0000000003e3e937
    ffffc90006fb7cb0: 0000000000000000 0000000000000000
    ffffc90006fb7cc0: 8d7c0b56b7874b00 ffff88812cbd3000

About the Fixes:
Why did it take eight years to be discovered?

The problem requires the following conditions to occur:
1. The device memory should be large enough.
2. Pages in the LRU(active_anon) list are mostly from the ZONE_NORMAL area.
3. The memory in ZONE_DMA32 needs to reach the watermark.

If the memory is not large enough, or if the usage design of ZONE_DMA32
area memory is reasonable, this problem is difficult to detect.

notes:
The problem is most likely to occur in ZONE_DMA32 and ZONE_NORMAL,
but other suitable scenarios may also trigger the problem.

Link: https://lkml.kernel.org/r/20241119060842.274072-1-liuye@kylinos.cn
Fixes: b2e1875 ("mm, vmscan: begin reclaiming pages on a per-node basis")
Signed-off-by: liuye <liuye@kylinos.cn>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Yang Shi <yang@os.amperecomputing.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

When COWing a relocation tree path, at relocation.c:replace_path(), we
can trigger a lockdep splat while we are in the btrfs_search_slot() call
against the relocation root. This happens in that callchain at
ctree.c:read_block_for_search() when we happen to find a child extent
buffer already loaded through the fs tree with a lockdep class set to
the fs tree. So when we attempt to lock that extent buffer through a
relocation tree we have to reset the lockdep class to the class for a
relocation tree, since a relocation tree has extent buffers that used
to belong to a fs tree and may currently be already loaded (we swap
extent buffers between the two trees at the end of replace_path()).

However we are missing calls to btrfs_maybe_reset_lockdep_class() to reset
the lockdep class at ctree.c:read_block_for_search() before we read lock
an extent buffer, just like we did for btrfs_search_slot() in commit
b40130b ("btrfs: fix lockdep splat with reloc root extent buffers").

So add the missing btrfs_maybe_reset_lockdep_class() calls before the
attempts to read lock an extent buffer at ctree.c:read_block_for_search().

The lockdep splat was reported by syzbot and it looks like this:

   ======================================================
   WARNING: possible circular locking dependency detected
   6.13.0-rc5-syzkaller-00163-gab75170520d4 #0 Not tainted
   ------------------------------------------------------
   syz.0.0/5335 is trying to acquire lock:
   ffff8880545dbc38 (btrfs-tree-01){++++}-{4:4}, at: btrfs_tree_read_lock_nested+0x2f/0x250 fs/btrfs/locking.c:146

   but task is already holding lock:
   ffff8880545dba58 (btrfs-treloc-02/1){+.+.}-{4:4}, at: btrfs_tree_lock_nested+0x2f/0x250 fs/btrfs/locking.c:189

   which lock already depends on the new lock.

   the existing dependency chain (in reverse order) is:

   -> #2 (btrfs-treloc-02/1){+.+.}-{4:4}:
          reacquire_held_locks+0x3eb/0x690 kernel/locking/lockdep.c:5374
          __lock_release kernel/locking/lockdep.c:5563 [inline]
          lock_release+0x396/0xa30 kernel/locking/lockdep.c:5870
          up_write+0x79/0x590 kernel/locking/rwsem.c:1629
          btrfs_force_cow_block+0x14b3/0x1fd0 fs/btrfs/ctree.c:660
          btrfs_cow_block+0x371/0x830 fs/btrfs/ctree.c:755
          btrfs_search_slot+0xc01/0x3180 fs/btrfs/ctree.c:2153
          replace_path+0x1243/0x2740 fs/btrfs/relocation.c:1224
          merge_reloc_root+0xc46/0x1ad0 fs/btrfs/relocation.c:1692
          merge_reloc_roots+0x3b3/0x980 fs/btrfs/relocation.c:1942
          relocate_block_group+0xb0a/0xd40 fs/btrfs/relocation.c:3754
          btrfs_relocate_block_group+0x77d/0xd90 fs/btrfs/relocation.c:4087
          btrfs_relocate_chunk+0x12c/0x3b0 fs/btrfs/volumes.c:3494
          __btrfs_balance+0x1b0f/0x26b0 fs/btrfs/volumes.c:4278
          btrfs_balance+0xbdc/0x10c0 fs/btrfs/volumes.c:4655
          btrfs_ioctl_balance+0x493/0x7c0 fs/btrfs/ioctl.c:3670
          vfs_ioctl fs/ioctl.c:51 [inline]
          __do_sys_ioctl fs/ioctl.c:906 [inline]
          __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892
          do_syscall_x64 arch/x86/entry/common.c:52 [inline]
          do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
          entry_SYSCALL_64_after_hwframe+0x77/0x7f

   -> #1 (btrfs-tree-01/1){+.+.}-{4:4}:
          lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
          down_write_nested+0xa2/0x220 kernel/locking/rwsem.c:1693
          btrfs_tree_lock_nested+0x2f/0x250 fs/btrfs/locking.c:189
          btrfs_init_new_buffer fs/btrfs/extent-tree.c:5052 [inline]
          btrfs_alloc_tree_block+0x41c/0x1440 fs/btrfs/extent-tree.c:5132
          btrfs_force_cow_block+0x526/0x1fd0 fs/btrfs/ctree.c:573
          btrfs_cow_block+0x371/0x830 fs/btrfs/ctree.c:755
          btrfs_search_slot+0xc01/0x3180 fs/btrfs/ctree.c:2153
          btrfs_insert_empty_items+0x9c/0x1a0 fs/btrfs/ctree.c:4351
          btrfs_insert_empty_item fs/btrfs/ctree.h:688 [inline]
          btrfs_insert_inode_ref+0x2bb/0xf80 fs/btrfs/inode-item.c:330
          btrfs_rename_exchange fs/btrfs/inode.c:7990 [inline]
          btrfs_rename2+0xcb7/0x2b90 fs/btrfs/inode.c:8374
          vfs_rename+0xbdb/0xf00 fs/namei.c:5067
          do_renameat2+0xd94/0x13f0 fs/namei.c:5224
          __do_sys_renameat2 fs/namei.c:5258 [inline]
          __se_sys_renameat2 fs/namei.c:5255 [inline]
          __x64_sys_renameat2+0xce/0xe0 fs/namei.c:5255
          do_syscall_x64 arch/x86/entry/common.c:52 [inline]
          do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
          entry_SYSCALL_64_after_hwframe+0x77/0x7f

   -> #0 (btrfs-tree-01){++++}-{4:4}:
          check_prev_add kernel/locking/lockdep.c:3161 [inline]
          check_prevs_add kernel/locking/lockdep.c:3280 [inline]
          validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
          __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
          lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
          down_read_nested+0xb5/0xa50 kernel/locking/rwsem.c:1649
          btrfs_tree_read_lock_nested+0x2f/0x250 fs/btrfs/locking.c:146
          btrfs_tree_read_lock fs/btrfs/locking.h:188 [inline]
          read_block_for_search+0x718/0xbb0 fs/btrfs/ctree.c:1610
          btrfs_search_slot+0x1274/0x3180 fs/btrfs/ctree.c:2237
          replace_path+0x1243/0x2740 fs/btrfs/relocation.c:1224
          merge_reloc_root+0xc46/0x1ad0 fs/btrfs/relocation.c:1692
          merge_reloc_roots+0x3b3/0x980 fs/btrfs/relocation.c:1942
          relocate_block_group+0xb0a/0xd40 fs/btrfs/relocation.c:3754
          btrfs_relocate_block_group+0x77d/0xd90 fs/btrfs/relocation.c:4087
          btrfs_relocate_chunk+0x12c/0x3b0 fs/btrfs/volumes.c:3494
          __btrfs_balance+0x1b0f/0x26b0 fs/btrfs/volumes.c:4278
          btrfs_balance+0xbdc/0x10c0 fs/btrfs/volumes.c:4655
          btrfs_ioctl_balance+0x493/0x7c0 fs/btrfs/ioctl.c:3670
          vfs_ioctl fs/ioctl.c:51 [inline]
          __do_sys_ioctl fs/ioctl.c:906 [inline]
          __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892
          do_syscall_x64 arch/x86/entry/common.c:52 [inline]
          do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
          entry_SYSCALL_64_after_hwframe+0x77/0x7f

   other info that might help us debug this:

   Chain exists of:
     btrfs-tree-01 --> btrfs-tree-01/1 --> btrfs-treloc-02/1

    Possible unsafe locking scenario:

          CPU0                    CPU1
          ----                    ----
     lock(btrfs-treloc-02/1);
                                  lock(btrfs-tree-01/1);
                                  lock(btrfs-treloc-02/1);
     rlock(btrfs-tree-01);

    *** DEADLOCK ***

   8 locks held by syz.0.0/5335:
    #0: ffff88801e3ae420 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write_file+0x5e/0x200 fs/namespace.c:559
    #1: ffff888052c760d0 (&fs_info->reclaim_bgs_lock){+.+.}-{4:4}, at: __btrfs_balance+0x4c2/0x26b0 fs/btrfs/volumes.c:4183
    #2: ffff888052c74850 (&fs_info->cleaner_mutex){+.+.}-{4:4}, at: btrfs_relocate_block_group+0x775/0xd90 fs/btrfs/relocation.c:4086
    #3: ffff88801e3ae610 (sb_internal#2){.+.+}-{0:0}, at: merge_reloc_root+0xf11/0x1ad0 fs/btrfs/relocation.c:1659
    #4: ffff888052c76470 (btrfs_trans_num_writers){++++}-{0:0}, at: join_transaction+0x405/0xda0 fs/btrfs/transaction.c:288
    #5: ffff888052c76498 (btrfs_trans_num_extwriters){++++}-{0:0}, at: join_transaction+0x405/0xda0 fs/btrfs/transaction.c:288
    #6: ffff8880545db878 (btrfs-tree-01/1){+.+.}-{4:4}, at: btrfs_tree_lock_nested+0x2f/0x250 fs/btrfs/locking.c:189
    #7: ffff8880545dba58 (btrfs-treloc-02/1){+.+.}-{4:4}, at: btrfs_tree_lock_nested+0x2f/0x250 fs/btrfs/locking.c:189

   stack backtrace:
   CPU: 0 UID: 0 PID: 5335 Comm: syz.0.0 Not tainted 6.13.0-rc5-syzkaller-00163-gab75170520d4 #0
   Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
   Call Trace:
    <TASK>
    __dump_stack lib/dump_stack.c:94 [inline]
    dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
    print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2074
    check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2206
    check_prev_add kernel/locking/lockdep.c:3161 [inline]
    check_prevs_add kernel/locking/lockdep.c:3280 [inline]
    validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
    __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
    lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
    down_read_nested+0xb5/0xa50 kernel/locking/rwsem.c:1649
    btrfs_tree_read_lock_nested+0x2f/0x250 fs/btrfs/locking.c:146
    btrfs_tree_read_lock fs/btrfs/locking.h:188 [inline]
    read_block_for_search+0x718/0xbb0 fs/btrfs/ctree.c:1610
    btrfs_search_slot+0x1274/0x3180 fs/btrfs/ctree.c:2237
    replace_path+0x1243/0x2740 fs/btrfs/relocation.c:1224
    merge_reloc_root+0xc46/0x1ad0 fs/btrfs/relocation.c:1692
    merge_reloc_roots+0x3b3/0x980 fs/btrfs/relocation.c:1942
    relocate_block_group+0xb0a/0xd40 fs/btrfs/relocation.c:3754
    btrfs_relocate_block_group+0x77d/0xd90 fs/btrfs/relocation.c:4087
    btrfs_relocate_chunk+0x12c/0x3b0 fs/btrfs/volumes.c:3494
    __btrfs_balance+0x1b0f/0x26b0 fs/btrfs/volumes.c:4278
    btrfs_balance+0xbdc/0x10c0 fs/btrfs/volumes.c:4655
    btrfs_ioctl_balance+0x493/0x7c0 fs/btrfs/ioctl.c:3670
    vfs_ioctl fs/ioctl.c:51 [inline]
    __do_sys_ioctl fs/ioctl.c:906 [inline]
    __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892
    do_syscall_x64 arch/x86/entry/common.c:52 [inline]
    do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
    entry_SYSCALL_64_after_hwframe+0x77/0x7f
   RIP: 0033:0x7f1ac6985d29
   Code: ff ff c3 (...)
   RSP: 002b:00007f1ac63fe038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
   RAX: ffffffffffffffda RBX: 00007f1ac6b76160 RCX: 00007f1ac6985d29
   RDX: 0000000020000180 RSI: 00000000c4009420 RDI: 0000000000000007
   RBP: 00007f1ac6a01b08 R08: 0000000000000000 R09: 0000000000000000
   R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
   R13: 0000000000000001 R14: 00007f1ac6b76160 R15: 00007fffda145a88
    </TASK>

Reported-by: syzbot+63913e558c084f7f8fdc@syzkaller.appspotmail.com
Link: https://lore.kernel.org/linux-btrfs/677b3014.050a0220.3b53b0.0064.GAE@google.com/
Fixes: 9978599 ("btrfs: reduce lock contention when eb cache miss for btree search")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

We have several places across the kernel where we want to access another
task's syscall arguments, such as ptrace(2), seccomp(2), etc., by making
a call to syscall_get_arguments().

This works for register arguments right away by accessing the task's
`regs' member of `struct pt_regs', however for stack arguments seen with
32-bit/o32 kernels things are more complicated.  Technically they ought
to be obtained from the user stack with calls to an access_remote_vm(),
but we have an easier way available already.

So as to be able to access syscall stack arguments as regular function
arguments following the MIPS calling convention we copy them over from
the user stack to the kernel stack in arch/mips/kernel/scall32-o32.S, in
handle_sys(), to the current stack frame's outgoing argument space at
the top of the stack, which is where the handler called expects to see
its incoming arguments.  This area is also pointed at by the `pt_regs'
pointer obtained by task_pt_regs().

Make the o32 stack argument space a proper member of `struct pt_regs'
then, by renaming the existing member from `pad0' to `args' and using
generated offsets to access the space.  No functional change though.

With the change in place the o32 kernel stack frame layout at the entry
to a syscall handler invoked by handle_sys() is therefore as follows:

$sp + 68 -> |         ...         | <- pt_regs.regs[9]
            +---------------------+
$sp + 64 -> |         $t0         | <- pt_regs.regs[8]
            +---------------------+
$sp + 60 -> |   $a3/argument #4   | <- pt_regs.regs[7]
            +---------------------+
$sp + 56 -> |   $a2/argument #3   | <- pt_regs.regs[6]
            +---------------------+
$sp + 52 -> |   $a1/argument #2   | <- pt_regs.regs[5]
            +---------------------+
$sp + 48 -> |   $a0/argument #1   | <- pt_regs.regs[4]
            +---------------------+
$sp + 44 -> |         $v1         | <- pt_regs.regs[3]
            +---------------------+
$sp + 40 -> |         $v0         | <- pt_regs.regs[2]
            +---------------------+
$sp + 36 -> |         $at         | <- pt_regs.regs[1]
            +---------------------+
$sp + 32 -> |        $zero        | <- pt_regs.regs[0]
            +---------------------+
$sp + 28 -> |  stack argument #8  | <- pt_regs.args[7]
            +---------------------+
$sp + 24 -> |  stack argument #7  | <- pt_regs.args[6]
            +---------------------+
$sp + 20 -> |  stack argument #6  | <- pt_regs.args[5]
            +---------------------+
$sp + 16 -> |  stack argument #5  | <- pt_regs.args[4]
            +---------------------+
$sp + 12 -> | psABI space for $a3 | <- pt_regs.args[3]
            +---------------------+
$sp +  8 -> | psABI space for $a2 | <- pt_regs.args[2]
            +---------------------+
$sp +  4 -> | psABI space for $a1 | <- pt_regs.args[1]
            +---------------------+
$sp +  0 -> | psABI space for $a0 | <- pt_regs.args[0]
            +---------------------+

holding user data received and with the first 4 frame slots reserved by
the psABI for the compiler to spill the incoming arguments from $a0-$a3
registers (which it sometimes does according to its needs) and the next
4 frame slots designated by the psABI for any stack function arguments
that follow.  This data is also available for other tasks to peek/poke
at as reqired and where permitted.

Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

This makes ptrace/get_syscall_info selftest pass on mips o32 and
mips64 o32 by fixing the following two test assertions:

1. get_syscall_info test assertion on mips o32:
  # get_syscall_info.c:218:get_syscall_info:Expected exp_args[5] (3134521044) == info.entry.args[4] (4911432)
  # get_syscall_info.c:219:get_syscall_info:wait #1: entry stop mismatch

2. get_syscall_info test assertion on mips64 o32:
  # get_syscall_info.c:209:get_syscall_info:Expected exp_args[2] (3134324433) == info.entry.args[1] (18446744072548908753)
  # get_syscall_info.c:210:get_syscall_info:wait #1: entry stop mismatch

The first assertion happens due to mips_get_syscall_arg() trying to access
another task's context but failing to do it properly because get_user() it
calls just peeks at the current task's context.  It usually does not crash
because the default user stack always gets assigned the same VMA, but it
is pure luck which mips_get_syscall_arg() wouldn't have if e.g. the stack
was switched (via setcontext(3) or however) or a non-default process's
thread peeked at, and in any case irrelevant data is obtained just as
observed with the test case.

mips_get_syscall_arg() ought to be using access_remote_vm() instead to
retrieve the other task's stack contents, but given that the data has been
already obtained and saved in `struct pt_regs' it would be an overkill.

The first assertion is fixed for mips o32 by using struct pt_regs.args
instead of get_user() to obtain syscall arguments.  This approach works
due to this piece in arch/mips/kernel/scall32-o32.S:

        /*
         * Ok, copy the args from the luser stack to the kernel stack.
         */

        .set    push
        .set    noreorder
        .set    nomacro

    load_a4: user_lw(t5, 16(t0))		# argument #5 from usp
    load_a5: user_lw(t6, 20(t0))		# argument #6 from usp
    load_a6: user_lw(t7, 24(t0))		# argument #7 from usp
    load_a7: user_lw(t8, 28(t0))		# argument #8 from usp
    loads_done:

        sw	t5, PT_ARG4(sp)		# argument #5 to ksp
        sw	t6, PT_ARG5(sp)		# argument #6 to ksp
        sw	t7, PT_ARG6(sp)		# argument #7 to ksp
        sw	t8, PT_ARG7(sp)		# argument #8 to ksp
        .set	pop

        .section __ex_table,"a"
        PTR_WD	load_a4, bad_stack_a4
        PTR_WD	load_a5, bad_stack_a5
        PTR_WD	load_a6, bad_stack_a6
        PTR_WD	load_a7, bad_stack_a7
        .previous

arch/mips/kernel/scall64-o32.S has analogous code for mips64 o32 that
allows fixing the issue by obtaining syscall arguments from struct
pt_regs.regs[4..11] instead of the erroneous use of get_user().

The second assertion is fixed by truncating 64-bit values to 32-bit
syscall arguments.

Fixes: c0ff3c5 ("MIPS: Enable HAVE_ARCH_TRACEHOOK.")
Signed-off-by: Dmitry V. Levin <ldv@strace.io>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

In recent kernels, there are lockdep splats around the
struct request_queue::io_lockdep_map, similar to [1], but they
typically don't show up until reclaim with writeback happens.

Having multiple kernel versions released with a known risc of kernel
deadlock during reclaim writeback should IMHO be addressed and
backported to -stable with the highest priority.

In order to have these lockdep splats show up earlier,
preferrably during system initialization, prime the
struct request_queue::io_lockdep_map as GFP_KERNEL reclaim-
tainted. This will instead lead to lockdep splats looking similar
to [2], but without the need for reclaim + writeback
happening.

[1]:
[  189.762244] ======================================================
[  189.762432] WARNING: possible circular locking dependency detected
[  189.762441] 6.14.0-rc6-xe+ #6 Tainted: G     U
[  189.762450] ------------------------------------------------------
[  189.762459] kswapd0/119 is trying to acquire lock:
[  189.762467] ffff888110ceb710 (&q->q_usage_counter(io)#26){++++}-{0:0}, at: __submit_bio+0x76/0x230
[  189.762485]
               but task is already holding lock:
[  189.762494] ffffffff834c97c0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0xbe/0xb00
[  189.762507]
               which lock already depends on the new lock.

[  189.762519]
               the existing dependency chain (in reverse order) is:
[  189.762529]
               -> #2 (fs_reclaim){+.+.}-{0:0}:
[  189.762540]        fs_reclaim_acquire+0xc5/0x100
[  189.762548]        kmem_cache_alloc_lru_noprof+0x4a/0x480
[  189.762558]        alloc_inode+0xaa/0xe0
[  189.762566]        iget_locked+0x157/0x330
[  189.762573]        kernfs_get_inode+0x1b/0x110
[  189.762582]        kernfs_get_tree+0x1b0/0x2e0
[  189.762590]        sysfs_get_tree+0x1f/0x60
[  189.762597]        vfs_get_tree+0x2a/0xf0
[  189.762605]        path_mount+0x4cd/0xc00
[  189.762613]        __x64_sys_mount+0x119/0x150
[  189.762621]        x64_sys_call+0x14f2/0x2310
[  189.762630]        do_syscall_64+0x91/0x180
[  189.762637]        entry_SYSCALL_64_after_hwframe+0x76/0x7e
[  189.762647]
               -> #1 (&root->kernfs_rwsem){++++}-{3:3}:
[  189.762659]        down_write+0x3e/0xf0
[  189.762667]        kernfs_remove+0x32/0x60
[  189.762676]        sysfs_remove_dir+0x4f/0x60
[  189.762685]        __kobject_del+0x33/0xa0
[  189.762709]        kobject_del+0x13/0x30
[  189.762716]        elv_unregister_queue+0x52/0x80
[  189.762725]        elevator_switch+0x68/0x360
[  189.762733]        elv_iosched_store+0x14b/0x1b0
[  189.762756]        queue_attr_store+0x181/0x1e0
[  189.762765]        sysfs_kf_write+0x49/0x80
[  189.762773]        kernfs_fop_write_iter+0x17d/0x250
[  189.762781]        vfs_write+0x281/0x540
[  189.762790]        ksys_write+0x72/0xf0
[  189.762798]        __x64_sys_write+0x19/0x30
[  189.762807]        x64_sys_call+0x2a3/0x2310
[  189.762815]        do_syscall_64+0x91/0x180
[  189.762823]        entry_SYSCALL_64_after_hwframe+0x76/0x7e
[  189.762833]
               -> #0 (&q->q_usage_counter(io)#26){++++}-{0:0}:
[  189.762845]        __lock_acquire+0x1525/0x2760
[  189.762854]        lock_acquire+0xca/0x310
[  189.762861]        blk_mq_submit_bio+0x8a2/0xba0
[  189.762870]        __submit_bio+0x76/0x230
[  189.762878]        submit_bio_noacct_nocheck+0x323/0x430
[  189.762888]        submit_bio_noacct+0x2cc/0x620
[  189.762896]        submit_bio+0x38/0x110
[  189.762904]        __swap_writepage+0xf5/0x380
[  189.762912]        swap_writepage+0x3c7/0x600
[  189.762920]        shmem_writepage+0x3da/0x4f0
[  189.762929]        pageout+0x13f/0x310
[  189.762937]        shrink_folio_list+0x61c/0xf60
[  189.763261]        evict_folios+0x378/0xcd0
[  189.763584]        try_to_shrink_lruvec+0x1b0/0x360
[  189.763946]        shrink_one+0x10e/0x200
[  189.764266]        shrink_node+0xc02/0x1490
[  189.764586]        balance_pgdat+0x563/0xb00
[  189.764934]        kswapd+0x1e8/0x430
[  189.765249]        kthread+0x10b/0x260
[  189.765559]        ret_from_fork+0x44/0x70
[  189.765889]        ret_from_fork_asm+0x1a/0x30
[  189.766198]
               other info that might help us debug this:

[  189.767089] Chain exists of:
                 &q->q_usage_counter(io)#26 --> &root->kernfs_rwsem --> fs_reclaim

[  189.767971]  Possible unsafe locking scenario:

[  189.768555]        CPU0                    CPU1
[  189.768849]        ----                    ----
[  189.769136]   lock(fs_reclaim);
[  189.769421]                                lock(&root->kernfs_rwsem);
[  189.769714]                                lock(fs_reclaim);
[  189.770016]   rlock(&q->q_usage_counter(io)#26);
[  189.770305]
                *** DEADLOCK ***

[  189.771167] 1 lock held by kswapd0/119:
[  189.771453]  #0: ffffffff834c97c0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0xbe/0xb00
[  189.771770]
               stack backtrace:
[  189.772351] CPU: 4 UID: 0 PID: 119 Comm: kswapd0 Tainted: G     U             6.14.0-rc6-xe+ #6
[  189.772353] Tainted: [U]=USER
[  189.772354] Hardware name: ASUS System Product Name/PRIME B560M-A AC, BIOS 2001 02/01/2023
[  189.772354] Call Trace:
[  189.772355]  <TASK>
[  189.772356]  dump_stack_lvl+0x6e/0xa0
[  189.772359]  dump_stack+0x10/0x18
[  189.772360]  print_circular_bug.cold+0x17a/0x1b7
[  189.772363]  check_noncircular+0x13a/0x150
[  189.772365]  ? __pfx_stack_trace_consume_entry+0x10/0x10
[  189.772368]  __lock_acquire+0x1525/0x2760
[  189.772368]  ? ret_from_fork_asm+0x1a/0x30
[  189.772371]  lock_acquire+0xca/0x310
[  189.772372]  ? __submit_bio+0x76/0x230
[  189.772375]  ? lock_release+0xd5/0x2c0
[  189.772376]  blk_mq_submit_bio+0x8a2/0xba0
[  189.772378]  ? __submit_bio+0x76/0x230
[  189.772380]  __submit_bio+0x76/0x230
[  189.772382]  ? trace_hardirqs_on+0x1e/0xe0
[  189.772384]  submit_bio_noacct_nocheck+0x323/0x430
[  189.772386]  ? submit_bio_noacct_nocheck+0x323/0x430
[  189.772387]  ? __might_sleep+0x58/0xa0
[  189.772390]  submit_bio_noacct+0x2cc/0x620
[  189.772391]  ? count_memcg_events+0x68/0x90
[  189.772393]  submit_bio+0x38/0x110
[  189.772395]  __swap_writepage+0xf5/0x380
[  189.772396]  swap_writepage+0x3c7/0x600
[  189.772397]  shmem_writepage+0x3da/0x4f0
[  189.772401]  pageout+0x13f/0x310
[  189.772406]  shrink_folio_list+0x61c/0xf60
[  189.772409]  ? isolate_folios+0xe80/0x16b0
[  189.772410]  ? mark_held_locks+0x46/0x90
[  189.772412]  evict_folios+0x378/0xcd0
[  189.772414]  ? evict_folios+0x34a/0xcd0
[  189.772415]  ? lock_is_held_type+0xa3/0x130
[  189.772417]  try_to_shrink_lruvec+0x1b0/0x360
[  189.772420]  shrink_one+0x10e/0x200
[  189.772421]  shrink_node+0xc02/0x1490
[  189.772423]  ? shrink_node+0xa08/0x1490
[  189.772424]  ? shrink_node+0xbd8/0x1490
[  189.772425]  ? mem_cgroup_iter+0x366/0x480
[  189.772427]  balance_pgdat+0x563/0xb00
[  189.772428]  ? balance_pgdat+0x563/0xb00
[  189.772430]  ? trace_hardirqs_on+0x1e/0xe0
[  189.772431]  ? finish_task_switch.isra.0+0xcb/0x330
[  189.772433]  ? __switch_to_asm+0x33/0x70
[  189.772437]  kswapd+0x1e8/0x430
[  189.772438]  ? __pfx_autoremove_wake_function+0x10/0x10
[  189.772440]  ? __pfx_kswapd+0x10/0x10
[  189.772441]  kthread+0x10b/0x260
[  189.772443]  ? __pfx_kthread+0x10/0x10
[  189.772444]  ret_from_fork+0x44/0x70
[  189.772446]  ? __pfx_kthread+0x10/0x10
[  189.772447]  ret_from_fork_asm+0x1a/0x30
[  189.772450]  </TASK>

[2]:
[    8.760253] ======================================================
[    8.760254] WARNING: possible circular locking dependency detected
[    8.760255] 6.14.0-rc6-xe+ #7 Tainted: G     U
[    8.760256] ------------------------------------------------------
[    8.760257] (udev-worker)/674 is trying to acquire lock:
[    8.760259] ffff888100e39148 (&root->kernfs_rwsem){++++}-{3:3}, at: kernfs_remove+0x32/0x60
[    8.760265]
               but task is already holding lock:
[    8.760266] ffff888110dc7680 (&q->q_usage_counter(io)#27){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x12/0x30
[    8.760272]
               which lock already depends on the new lock.

[    8.760272]
               the existing dependency chain (in reverse order) is:
[    8.760273]
               -> #2 (&q->q_usage_counter(io)#27){++++}-{0:0}:
[    8.760276]        blk_alloc_queue+0x30a/0x350
[    8.760279]        blk_mq_alloc_queue+0x6b/0xe0
[    8.760281]        scsi_alloc_sdev+0x276/0x3c0
[    8.760284]        scsi_probe_and_add_lun+0x22a/0x440
[    8.760286]        __scsi_scan_target+0x109/0x230
[    8.760288]        scsi_scan_channel+0x65/0xc0
[    8.760290]        scsi_scan_host_selected+0xff/0x140
[    8.760292]        do_scsi_scan_host+0xa7/0xc0
[    8.760293]        do_scan_async+0x1c/0x160
[    8.760295]        async_run_entry_fn+0x32/0x150
[    8.760299]        process_one_work+0x224/0x5f0
[    8.760302]        worker_thread+0x1d4/0x3e0
[    8.760304]        kthread+0x10b/0x260
[    8.760306]        ret_from_fork+0x44/0x70
[    8.760309]        ret_from_fork_asm+0x1a/0x30
[    8.760312]
               -> #1 (fs_reclaim){+.+.}-{0:0}:
[    8.760315]        fs_reclaim_acquire+0xc5/0x100
[    8.760317]        kmem_cache_alloc_lru_noprof+0x4a/0x480
[    8.760319]        alloc_inode+0xaa/0xe0
[    8.760322]        iget_locked+0x157/0x330
[    8.760323]        kernfs_get_inode+0x1b/0x110
[    8.760325]        kernfs_get_tree+0x1b0/0x2e0
[    8.760327]        sysfs_get_tree+0x1f/0x60
[    8.760329]        vfs_get_tree+0x2a/0xf0
[    8.760332]        path_mount+0x4cd/0xc00
[    8.760334]        __x64_sys_mount+0x119/0x150
[    8.760336]        x64_sys_call+0x14f2/0x2310
[    8.760338]        do_syscall_64+0x91/0x180
[    8.760340]        entry_SYSCALL_64_after_hwframe+0x76/0x7e
[    8.760342]
               -> #0 (&root->kernfs_rwsem){++++}-{3:3}:
[    8.760345]        __lock_acquire+0x1525/0x2760
[    8.760347]        lock_acquire+0xca/0x310
[    8.760348]        down_write+0x3e/0xf0
[    8.760350]        kernfs_remove+0x32/0x60
[    8.760351]        sysfs_remove_dir+0x4f/0x60
[    8.760353]        __kobject_del+0x33/0xa0
[    8.760355]        kobject_del+0x13/0x30
[    8.760356]        elv_unregister_queue+0x52/0x80
[    8.760358]        elevator_switch+0x68/0x360
[    8.760360]        elv_iosched_store+0x14b/0x1b0
[    8.760362]        queue_attr_store+0x181/0x1e0
[    8.760364]        sysfs_kf_write+0x49/0x80
[    8.760366]        kernfs_fop_write_iter+0x17d/0x250
[    8.760367]        vfs_write+0x281/0x540
[    8.760370]        ksys_write+0x72/0xf0
[    8.760372]        __x64_sys_write+0x19/0x30
[    8.760374]        x64_sys_call+0x2a3/0x2310
[    8.760376]        do_syscall_64+0x91/0x180
[    8.760377]        entry_SYSCALL_64_after_hwframe+0x76/0x7e
[    8.760380]
               other info that might help us debug this:

[    8.760380] Chain exists of:
                 &root->kernfs_rwsem --> fs_reclaim --> &q->q_usage_counter(io)#27

[    8.760384]  Possible unsafe locking scenario:

[    8.760384]        CPU0                    CPU1
[    8.760385]        ----                    ----
[    8.760385]   lock(&q->q_usage_counter(io)#27);
[    8.760387]                                lock(fs_reclaim);
[    8.760388]                                lock(&q->q_usage_counter(io)#27);
[    8.760390]   lock(&root->kernfs_rwsem);
[    8.760391]
                *** DEADLOCK ***

[    8.760391] 6 locks held by (udev-worker)/674:
[    8.760392]  #0: ffff8881209ac420 (sb_writers#4){.+.+}-{0:0}, at: ksys_write+0x72/0xf0
[    8.760398]  #1: ffff88810c80f488 (&of->mutex#2){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x136/0x250
[    8.760402]  #2: ffff888125d1d330 (kn->active#101){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x13f/0x250
[    8.760406]  #3: ffff888110dc7bb0 (&q->sysfs_lock){+.+.}-{3:3}, at: queue_attr_store+0x148/0x1e0
[    8.760411]  #4: ffff888110dc7680 (&q->q_usage_counter(io)#27){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x12/0x30
[    8.760416]  #5: ffff888110dc76b8 (&q->q_usage_counter(queue)#27){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x12/0x30
[    8.760421]
               stack backtrace:
[    8.760422] CPU: 7 UID: 0 PID: 674 Comm: (udev-worker) Tainted: G     U             6.14.0-rc6-xe+ #7
[    8.760424] Tainted: [U]=USER
[    8.760425] Hardware name: ASUS System Product Name/PRIME B560M-A AC, BIOS 2001 02/01/2023
[    8.760426] Call Trace:
[    8.760427]  <TASK>
[    8.760428]  dump_stack_lvl+0x6e/0xa0
[    8.760431]  dump_stack+0x10/0x18
[    8.760433]  print_circular_bug.cold+0x17a/0x1b7
[    8.760437]  check_noncircular+0x13a/0x150
[    8.760441]  ? save_trace+0x54/0x360
[    8.760445]  __lock_acquire+0x1525/0x2760
[    8.760446]  ? irqentry_exit+0x3a/0xb0
[    8.760448]  ? sysvec_apic_timer_interrupt+0x57/0xc0
[    8.760452]  lock_acquire+0xca/0x310
[    8.760453]  ? kernfs_remove+0x32/0x60
[    8.760457]  down_write+0x3e/0xf0
[    8.760459]  ? kernfs_remove+0x32/0x60
[    8.760460]  kernfs_remove+0x32/0x60
[    8.760462]  sysfs_remove_dir+0x4f/0x60
[    8.760464]  __kobject_del+0x33/0xa0
[    8.760466]  kobject_del+0x13/0x30
[    8.760467]  elv_unregister_queue+0x52/0x80
[    8.760470]  elevator_switch+0x68/0x360
[    8.760472]  elv_iosched_store+0x14b/0x1b0
[    8.760475]  queue_attr_store+0x181/0x1e0
[    8.760479]  ? lock_acquire+0xca/0x310
[    8.760480]  ? kernfs_fop_write_iter+0x13f/0x250
[    8.760482]  ? lock_is_held_type+0xa3/0x130
[    8.760485]  sysfs_kf_write+0x49/0x80
[    8.760487]  kernfs_fop_write_iter+0x17d/0x250
[    8.760489]  vfs_write+0x281/0x540
[    8.760494]  ksys_write+0x72/0xf0
[    8.760497]  __x64_sys_write+0x19/0x30
[    8.760499]  x64_sys_call+0x2a3/0x2310
[    8.760502]  do_syscall_64+0x91/0x180
[    8.760504]  ? trace_hardirqs_off+0x5d/0xe0
[    8.760506]  ? handle_softirqs+0x479/0x4d0
[    8.760508]  ? hrtimer_interrupt+0x13f/0x280
[    8.760511]  ? irqentry_exit_to_user_mode+0x8b/0x260
[    8.760513]  ? clear_bhb_loop+0x15/0x70
[    8.760515]  ? clear_bhb_loop+0x15/0x70
[    8.760516]  ? clear_bhb_loop+0x15/0x70
[    8.760518]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
[    8.760520] RIP: 0033:0x7aa3bf2f5504
[    8.760522] Code: c7 00 16 00 00 00 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 80 3d c5 8b 10 00 00 74 13 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3 0f 1f 00 55 48 89 e5 48 83 ec 20 48 89
[    8.760523] RSP: 002b:00007ffc1e3697d8 EFLAGS: 00000202 ORIG_RAX: 0000000000000001
[    8.760526] RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007aa3bf2f5504
[    8.760527] RDX: 0000000000000003 RSI: 00007ffc1e369ae0 RDI: 000000000000001c
[    8.760528] RBP: 00007ffc1e369800 R08: 00007aa3bf3f51c8 R09: 00007ffc1e3698b0
[    8.760528] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000003
[    8.760529] R13: 00007ffc1e369ae0 R14: 0000613ccf21f2f0 R15: 00007aa3bf3f4e80
[    8.760533]  </TASK>

v2:
- Update a code comment to increase readability (Ming Lei).

Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250318095548.5187-1-thomas.hellstrom@linux.intel.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

The commit '245618f8e45f ("block: protect wbt_lat_usec using q->
elevator_lock")' introduced q->elevator_lock to protect updates
to blk-wbt parameters when writing to the sysfs attribute wbt_
lat_usec and the cgroup attribute io.cost.qos.  However, both
these attributes also acquire q->rq_qos_mutex, leading to the
following lockdep warning:

======================================================
WARNING: possible circular locking dependency detected
6.14.0-rc5+ #138 Not tainted
------------------------------------------------------
bash/5902 is trying to acquire lock:
c000000085d495a0 (&q->rq_qos_mutex){+.+.}-{4:4}, at: wbt_init+0x164/0x238

but task is already holding lock:
c000000085d498c8 (&q->elevator_lock){+.+.}-{4:4}, at: queue_wb_lat_store+0xb0/0x20c

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (&q->elevator_lock){+.+.}-{4:4}:
        __mutex_lock+0xf0/0xa58
        ioc_qos_write+0x16c/0x85c
        cgroup_file_write+0xc4/0x32c
        kernfs_fop_write_iter+0x1b8/0x29c
        vfs_write+0x410/0x584
        ksys_write+0x84/0x140
        system_call_exception+0x134/0x360
        system_call_vectored_common+0x15c/0x2ec

-> #0 (&q->rq_qos_mutex){+.+.}-{4:4}:
        __lock_acquire+0x1b6c/0x2ae0
        lock_acquire+0x140/0x430
        __mutex_lock+0xf0/0xa58
        wbt_init+0x164/0x238
        queue_wb_lat_store+0x1dc/0x20c
        queue_attr_store+0x12c/0x164
        sysfs_kf_write+0x6c/0xb0
        kernfs_fop_write_iter+0x1b8/0x29c
        vfs_write+0x410/0x584
        ksys_write+0x84/0x140
        system_call_exception+0x134/0x360
        system_call_vectored_common+0x15c/0x2ec

other info that might help us debug this:

    Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
    lock(&q->elevator_lock);
                                lock(&q->rq_qos_mutex);
                                lock(&q->elevator_lock);
    lock(&q->rq_qos_mutex);

    *** DEADLOCK ***

6 locks held by bash/5902:
    #0: c000000051122400 (sb_writers#3){.+.+}-{0:0}, at: ksys_write+0x84/0x140
    #1: c00000007383f088 (&of->mutex#2){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x174/0x29c
    #2: c000000008550428 (kn->active#182){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x180/0x29c
    #3: c000000085d493a8 (&q->q_usage_counter(io)#5){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x28/0x40
    #4: c000000085d493e0 (&q->q_usage_counter(queue)#5){++++}-{0:0}, at: blk_mq_freeze_queue_nomemsave+0x28/0x40
    #5: c000000085d498c8 (&q->elevator_lock){+.+.}-{4:4}, at: queue_wb_lat_store+0xb0/0x20c

stack backtrace:
CPU: 17 UID: 0 PID: 5902 Comm: bash Kdump: loaded Not tainted 6.14.0-rc5+ #138
Hardware name: IBM,9043-MRX POWER10 (architected) 0x800200 0xf000006 of:IBM,FW1060.00 (NM1060_028) hv:phyp pSeries
Call Trace:
[c0000000721ef590] [c00000000118f8a8] dump_stack_lvl+0x108/0x18c (unreliable)
[c0000000721ef5c0] [c00000000022563c] print_circular_bug+0x448/0x604
[c0000000721ef670] [c000000000225a44] check_noncircular+0x24c/0x26c
[c0000000721ef740] [c00000000022bf28] __lock_acquire+0x1b6c/0x2ae0
[c0000000721ef870] [c000000000229240] lock_acquire+0x140/0x430
[c0000000721ef970] [c0000000011cfbec] __mutex_lock+0xf0/0xa58
[c0000000721efaa0] [c00000000096c46c] wbt_init+0x164/0x238
[c0000000721efaf0] [c0000000008f8cd8] queue_wb_lat_store+0x1dc/0x20c
[c0000000721efb50] [c0000000008f8fa0] queue_attr_store+0x12c/0x164
[c0000000721efc60] [c0000000007c11cc] sysfs_kf_write+0x6c/0xb0
[c0000000721efca0] [c0000000007bfa4c] kernfs_fop_write_iter+0x1b8/0x29c
[c0000000721efcf0] [c0000000006a281c] vfs_write+0x410/0x584
[c0000000721efdc0] [c0000000006a2cc8] ksys_write+0x84/0x140
[c0000000721efe10] [c000000000031b64] system_call_exception+0x134/0x360
[c0000000721efe50] [c00000000000cedc] system_call_vectored_common+0x15c/0x2ec

>From the above log it's apparent that method which writes to sysfs attr
wbt_lat_usec acquires q->elevator_lock first, and then acquires q->rq_
qos_mutex. However the another method which writes to io.cost.qos,
acquires q->rq_qos_mutex first, and then acquires q->rq_qos_mutex. So
this could potentially cause the deadlock.

A closer look at ioc_qos_write shows that correcting the lock order is
non-trivial because q->rq_qos_mutex is acquired in blkg_conf_open_bdev
and released in blkg_conf_exit. The function blkg_conf_open_bdev is
responsible for parsing user input and finding the corresponding block
device (bdev) from the user provided major:minor number.

Since we do not know the bdev until blkg_conf_open_bdev completes, we
cannot simply move q->elevator_lock acquisition before blkg_conf_open_
bdev. So to address this, we intoduce new helpers blkg_conf_open_bdev_
frozen and blkg_conf_exit_frozen which are just wrappers around blkg_
conf_open_bdev and blkg_conf_exit respectively. The helper blkg_conf_
open_bdev_frozen is similar to blkg_conf_open_bdev, but additionally
freezes the queue, acquires q->elevator_lock and ensures the correct
locking order is followed between q->elevator_lock and q->rq_qos_mutex.
Similarly another helper blkg_conf_exit_frozen in addition to unfreezing
the queue ensures that we release the locks in correct order.

By using these helpers, now we maintain the same locking order in all
code paths where we update blk-wbt parameters.

Fixes: 245618f ("block: protect wbt_lat_usec using q->elevator_lock")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202503171650.cc082b66-lkp@intel.com
Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
Link: https://lore.kernel.org/r/20250319105518.468941-3-nilay@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

We have recently seen report of lockdep circular lock dependency warnings
on platforms like Skylake and Kabylake:

 ======================================================
 WARNING: possible circular locking dependency detected
 6.14.0-rc6-CI_DRM_16276-gca2c04fe76e8+ #1 Not tainted
 ------------------------------------------------------
 swapper/0/1 is trying to acquire lock:
 ffffffff8360ee48 (iommu_probe_device_lock){+.+.}-{3:3},
   at: iommu_probe_device+0x1d/0x70

 but task is already holding lock:
 ffff888102c7efa8 (&device->physical_node_lock){+.+.}-{3:3},
   at: intel_iommu_init+0xe75/0x11f0

 which lock already depends on the new lock.

 the existing dependency chain (in reverse order) is:

 -> #6 (&device->physical_node_lock){+.+.}-{3:3}:
        __mutex_lock+0xb4/0xe40
        mutex_lock_nested+0x1b/0x30
        intel_iommu_init+0xe75/0x11f0
        pci_iommu_init+0x13/0x70
        do_one_initcall+0x62/0x3f0
        kernel_init_freeable+0x3da/0x6a0
        kernel_init+0x1b/0x200
        ret_from_fork+0x44/0x70
        ret_from_fork_asm+0x1a/0x30

 -> #5 (dmar_global_lock){++++}-{3:3}:
        down_read+0x43/0x1d0
        enable_drhd_fault_handling+0x21/0x110
        cpuhp_invoke_callback+0x4c6/0x870
        cpuhp_issue_call+0xbf/0x1f0
        __cpuhp_setup_state_cpuslocked+0x111/0x320
        __cpuhp_setup_state+0xb0/0x220
        irq_remap_enable_fault_handling+0x3f/0xa0
        apic_intr_mode_init+0x5c/0x110
        x86_late_time_init+0x24/0x40
        start_kernel+0x895/0xbd0
        x86_64_start_reservations+0x18/0x30
        x86_64_start_kernel+0xbf/0x110
        common_startup_64+0x13e/0x141

 -> #4 (cpuhp_state_mutex){+.+.}-{3:3}:
        __mutex_lock+0xb4/0xe40
        mutex_lock_nested+0x1b/0x30
        __cpuhp_setup_state_cpuslocked+0x67/0x320
        __cpuhp_setup_state+0xb0/0x220
        page_alloc_init_cpuhp+0x2d/0x60
        mm_core_init+0x18/0x2c0
        start_kernel+0x576/0xbd0
        x86_64_start_reservations+0x18/0x30
        x86_64_start_kernel+0xbf/0x110
        common_startup_64+0x13e/0x141

 -> #3 (cpu_hotplug_lock){++++}-{0:0}:
        __cpuhp_state_add_instance+0x4f/0x220
        iova_domain_init_rcaches+0x214/0x280
        iommu_setup_dma_ops+0x1a4/0x710
        iommu_device_register+0x17d/0x260
        intel_iommu_init+0xda4/0x11f0
        pci_iommu_init+0x13/0x70
        do_one_initcall+0x62/0x3f0
        kernel_init_freeable+0x3da/0x6a0
        kernel_init+0x1b/0x200
        ret_from_fork+0x44/0x70
        ret_from_fork_asm+0x1a/0x30

 -> #2 (&domain->iova_cookie->mutex){+.+.}-{3:3}:
        __mutex_lock+0xb4/0xe40
        mutex_lock_nested+0x1b/0x30
        iommu_setup_dma_ops+0x16b/0x710
        iommu_device_register+0x17d/0x260
        intel_iommu_init+0xda4/0x11f0
        pci_iommu_init+0x13/0x70
        do_one_initcall+0x62/0x3f0
        kernel_init_freeable+0x3da/0x6a0
        kernel_init+0x1b/0x200
        ret_from_fork+0x44/0x70
        ret_from_fork_asm+0x1a/0x30

 -> #1 (&group->mutex){+.+.}-{3:3}:
        __mutex_lock+0xb4/0xe40
        mutex_lock_nested+0x1b/0x30
        __iommu_probe_device+0x24c/0x4e0
        probe_iommu_group+0x2b/0x50
        bus_for_each_dev+0x7d/0xe0
        iommu_device_register+0xe1/0x260
        intel_iommu_init+0xda4/0x11f0
        pci_iommu_init+0x13/0x70
        do_one_initcall+0x62/0x3f0
        kernel_init_freeable+0x3da/0x6a0
        kernel_init+0x1b/0x200
        ret_from_fork+0x44/0x70
        ret_from_fork_asm+0x1a/0x30

 -> #0 (iommu_probe_device_lock){+.+.}-{3:3}:
        __lock_acquire+0x1637/0x2810
        lock_acquire+0xc9/0x300
        __mutex_lock+0xb4/0xe40
        mutex_lock_nested+0x1b/0x30
        iommu_probe_device+0x1d/0x70
        intel_iommu_init+0xe90/0x11f0
        pci_iommu_init+0x13/0x70
        do_one_initcall+0x62/0x3f0
        kernel_init_freeable+0x3da/0x6a0
        kernel_init+0x1b/0x200
        ret_from_fork+0x44/0x70
        ret_from_fork_asm+0x1a/0x30

 other info that might help us debug this:

 Chain exists of:
   iommu_probe_device_lock --> dmar_global_lock -->
     &device->physical_node_lock

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(&device->physical_node_lock);
                                lock(dmar_global_lock);
                                lock(&device->physical_node_lock);
   lock(iommu_probe_device_lock);

  *** DEADLOCK ***

This driver uses a global lock to protect the list of enumerated DMA
remapping units. It is necessary due to the driver's support for dynamic
addition and removal of remapping units at runtime.

Two distinct code paths require iteration over this remapping unit list:

- Device registration and probing: the driver iterates the list to
  register each remapping unit with the upper layer IOMMU framework
  and subsequently probe the devices managed by that unit.
- Global configuration: Upper layer components may also iterate the list
  to apply configuration changes.

The lock acquisition order between these two code paths was reversed. This
caused lockdep warnings, indicating a risk of deadlock. Fix this warning
by releasing the global lock before invoking upper layer interfaces for
device registration.

Fixes: b150654 ("iommu/vt-d: Fix suspicious RCU usage")
Closes: https://lore.kernel.org/linux-iommu/SJ1PR11MB612953431F94F18C954C4A9CB9D32@SJ1PR11MB6129.namprd11.prod.outlook.com/
Tested-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20250317035714.1041549-1-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Chia-Yu Chang says:

====================
AccECN protocol preparation patch series

Please find the v7

v7 (03-Mar-2025)
- Move 2 new patches added in v6 to the next AccECN patch series

v6 (27-Dec-2024)
- Avoid removing removing the potential CA_ACK_WIN_UPDATE in ack_ev_flags of patch #1 (Eric Dumazet <edumazet@google.com>)
- Add reviewed-by tag in patches #2, #3, #4, #5, #6, #7, #8, #12, #14
- Foloiwng 2 new pathces are added after patch #9 (Patch that adds SKB_GSO_TCP_ACCECN)
  * New patch #10 to replace exisiting SKB_GSO_TCP_ECN with SKB_GSO_TCP_ACCECN in the driver to avoid CWR flag corruption
  * New patch #11 adds AccECN for virtio by adding new negotiation flag (VIRTIO_NET_F_HOST/GUEST_ACCECN) in feature handshake and translating Accurate ECN GSO flag between virtio_net_hdr (VIRTIO_NET_HDR_GSO_ACCECN) and skb header (SKB_GSO_TCP_ACCECN)
- Add detailed changelog and comments in #13 (Eric Dumazet <edumazet@google.com>)
- Move patch #14 to the next AccECN patch series (Eric Dumazet <edumazet@google.com>)

v5 (5-Nov-2024)
- Add helper function "tcp_flags_ntohs" to preserve last 2 bytes of TCP flags of patch #4 (Paolo Abeni <pabeni@redhat.com>)
- Fix reverse X-max tree order of patches #4, #11 (Paolo Abeni <pabeni@redhat.com>)
- Rename variable "delta" as "timestamp_delta" of patch #2 fo clariety
- Remove patch #14 in this series (Paolo Abeni <pabeni@redhat.com>, Joel Granados <joel.granados@kernel.org>)

v4 (21-Oct-2024)
- Fix line length warning of patches #2, #4, #8, #10, #11, #14
- Fix spaces preferred around '|' (ctx:VxV) warning of patch #7
- Add missing CC'ed of patches #4, #12, #14

v3 (19-Oct-2024)
- Fix build error in v2

v2 (18-Oct-2024)
- Fix warning caused by NETIF_F_GSO_ACCECN_BIT in patch #9 (Jakub Kicinski <kuba@kernel.org>)

The full patch series can be found in
https://github.com/L4STeam/linux-net-next/commits/upstream_l4steam/

The Accurate ECN draft can be found in
https://datatracker.ietf.org/doc/html/draft-ietf-tcpm-accurate-ecn-28
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

With the device instance lock, there is now a possibility of a deadlock:

[    1.211455] ============================================
[    1.211571] WARNING: possible recursive locking detected
[    1.211687] 6.14.0-rc5-01215-g032756b4ca7a-dirty #5 Not tainted
[    1.211823] --------------------------------------------
[    1.211936] ip/184 is trying to acquire lock:
[    1.212032] ffff8881024a4c30 (&dev->lock){+.+.}-{4:4}, at: dev_set_allmulti+0x4e/0xb0
[    1.212207]
[    1.212207] but task is already holding lock:
[    1.212332] ffff8881024a4c30 (&dev->lock){+.+.}-{4:4}, at: dev_open+0x50/0xb0
[    1.212487]
[    1.212487] other info that might help us debug this:
[    1.212626]  Possible unsafe locking scenario:
[    1.212626]
[    1.212751]        CPU0
[    1.212815]        ----
[    1.212871]   lock(&dev->lock);
[    1.212944]   lock(&dev->lock);
[    1.213016]
[    1.213016]  *** DEADLOCK ***
[    1.213016]
[    1.213143]  May be due to missing lock nesting notation
[    1.213143]
[    1.213294] 3 locks held by ip/184:
[    1.213371]  #0: ffffffff838b53e0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock+0x1b/0xa0
[    1.213543]  #1: ffffffff84e5fc70 (&net->rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock+0x37/0xa0
[    1.213727]  #2: ffff8881024a4c30 (&dev->lock){+.+.}-{4:4}, at: dev_open+0x50/0xb0
[    1.213895]
[    1.213895] stack backtrace:
[    1.213991] CPU: 0 UID: 0 PID: 184 Comm: ip Not tainted 6.14.0-rc5-01215-g032756b4ca7a-dirty #5
[    1.213993] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.16.3-1-1 04/01/2014
[    1.213994] Call Trace:
[    1.213995]  <TASK>
[    1.213996]  dump_stack_lvl+0x8e/0xd0
[    1.214000]  print_deadlock_bug+0x28b/0x2a0
[    1.214020]  lock_acquire+0xea/0x2a0
[    1.214027]  __mutex_lock+0xbf/0xd40
[    1.214038]  dev_set_allmulti+0x4e/0xb0 # real_dev->flags & IFF_ALLMULTI
[    1.214040]  vlan_dev_open+0xa5/0x170 # ndo_open on vlandev
[    1.214042]  __dev_open+0x145/0x270
[    1.214046]  __dev_change_flags+0xb0/0x1e0
[    1.214051]  netif_change_flags+0x22/0x60 # IFF_UP vlandev
[    1.214053]  dev_change_flags+0x61/0xb0 # for each device in group from dev->vlan_info
[    1.214055]  vlan_device_event+0x766/0x7c0 # on netdevsim0
[    1.214058]  notifier_call_chain+0x78/0x120
[    1.214062]  netif_open+0x6d/0x90
[    1.214064]  dev_open+0x5b/0xb0 # locks netdevsim0
[    1.214066]  bond_enslave+0x64c/0x1230
[    1.214075]  do_set_master+0x175/0x1e0 # on netdevsim0
[    1.214077]  do_setlink+0x516/0x13b0
[    1.214094]  rtnl_newlink+0xaba/0xb80
[    1.214132]  rtnetlink_rcv_msg+0x440/0x490
[    1.214144]  netlink_rcv_skb+0xeb/0x120
[    1.214150]  netlink_unicast+0x1f9/0x320
[    1.214153]  netlink_sendmsg+0x346/0x3f0
[    1.214157]  __sock_sendmsg+0x86/0xb0
[    1.214160]  ____sys_sendmsg+0x1c8/0x220
[    1.214164]  ___sys_sendmsg+0x28f/0x2d0
[    1.214179]  __x64_sys_sendmsg+0xef/0x140
[    1.214184]  do_syscall_64+0xec/0x1d0
[    1.214190]  entry_SYSCALL_64_after_hwframe+0x77/0x7f
[    1.214191] RIP: 0033:0x7f2d1b4a7e56

Device setup:

     netdevsim0 (down)
     ^        ^
  bond        netdevsim1.100@netdevsim1 allmulticast=on (down)

When we enslave the lower device (netdevsim0) which has a vlan, we
propagate vlan's allmuti/promisc flags during ndo_open. This causes
(re)locking on of the real_dev.

Propagate allmulti/promisc on flags change, not on the open. There
is a slight semantics change that vlans that are down now propagate
the flags, but this seems unlikely to result in the real issues.

Reproducer:

  echo 0 1 > /sys/bus/netdevsim/new_device

  dev_path=$(ls -d /sys/bus/netdevsim/devices/netdevsim0/net/*)
  dev=$(echo $dev_path | rev | cut -d/ -f1 | rev)

  ip link set dev $dev name netdevsim0
  ip link set dev netdevsim0 up

  ip link add link netdevsim0 name netdevsim0.100 type vlan id 100
  ip link set dev netdevsim0.100 allmulticast on down
  ip link add name bond1 type bond mode 802.3ad
  ip link set dev netdevsim0 down
  ip link set dev netdevsim0 master bond1
  ip link set dev bond1 up
  ip link show

Reported-by: syzbot+b0c03d76056ef6cd12a6@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/Z9CfXjLMKn6VLG5d@mini-arch/T/#m15ba130f53227c883e79fb969687d69d670337a0
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250313100657.2287455-1-sdf@fomichev.me
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

…-bridge-ports'

Petr Machata says:

====================
mlxsw: Add VXLAN to the same hardware domain as physical bridge ports

Amit Cohen writes:

Packets which are trapped to CPU for forwarding in software data path
are handled according to driver marking of skb->offload_{,l3}_fwd_mark.
Packets which are marked as L2-forwarded in hardware, will not be flooded
by the bridge to bridge ports which are in the same hardware domain as the
ingress port.

Currently, mlxsw does not add VXLAN bridge ports to the same hardware
domain as physical bridge ports despite the fact that the device is able
to forward packets to and from VXLAN tunnels in hardware. In some
scenarios this can result in remote VTEPs receiving duplicate packets.

To solve such packets duplication, add VXLAN bridge ports to the same
hardware domain as other bridge ports.

One complication is ARP suppression which requires the local VTEP to avoid
flooding ARP packets to remote VTEPs if the local VTEP is able to reply on
behalf of remote hosts. This is currently implemented by having the device
flood ARP packets in hardware and trapping them during VXLAN encapsulation,
but marking them with skb->offload_fwd_mark=1 so that the bridge will not
re-flood them to physical bridge ports.

The above scheme will break when VXLAN bridge ports are added to the same
hardware domain as physical bridge ports as ARP packets that cannot be
suppressed by the bridge will not be able to egress the VXLAN bridge ports
due to hardware domain filtering. This is solved by trapping ARP packets
when they enter the device and not marking them as being forwarded in
hardware.

Patch set overview:
Patch #1 sets hardware to trap ARP packets at layer 2
Patches #2-#4 are preparations for setting hardwarwe domain of VXLAN
Patch #5 sets hardware domain of VXLAN
Patch #6 extends VXLAN flood test to verify that this set solves the
packets duplication
====================

Link: https://patch.msgid.link/cover.1742224300.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Eduard Zingerman says:

====================
This patch set fixes a bug in copy_verifier_state() where the
loop_entry field was not copied. This omission led to incorrect
loop_entry fields remaining in env->cur_state, causing incorrect
decisions about loop entry assignments in update_loop_entry().

An example of an unsafe program accepted by the verifier due to this
bug can be found in patch #2. This bug can also cause an infinite loop
in the verifier, see patch #5.

Structure of the patch set:
- Patch #1 fixes the bug but has a significant negative impact on
  verification performance for sched_ext programs.
- Patch #3 mitigates the verification performance impact of patch #1
  by avoiding clean_live_states() for states whose loop_entry is still
  being verified. This reduces the number of processed instructions
  for sched_ext programs by 28–92% in some cases.
- Patches #5-6 simplify {get,update}_loop_entry() logic (and are not
  strictly necessary).
- Patches #7–10 mitigate the memory overhead introduced by patch #1
  when a program with iterator-based loop hits the 1M instruction
  limit. This is achieved by freeing states in env->free_list when
  their branches and used_as_loop_entry counts reach zero.

Patches #1-4 were previously sent as a part of [1].

[1] https://lore.kernel.org/bpf/20250122120442.3536298-1-eddyz87@gmail.com/
====================

Link: https://patch.msgid.link/20250215110411.3236773-1-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

…uctions

Add several ./test_progs tests:

  - arena_atomics/load_acquire
  - arena_atomics/store_release
  - verifier_load_acquire/*
  - verifier_store_release/*
  - verifier_precision/bpf_load_acquire
  - verifier_precision/bpf_store_release

The last two tests are added to check if backtrack_insn() handles the
new instructions correctly.

Additionally, the last test also makes sure that the verifier
"remembers" the value (in src_reg) we store-release into e.g. a stack
slot.  For example, if we take a look at the test program:

    #0:  r1 = 8;
      /* store_release((u64 *)(r10 - 8), r1); */
    #1:  .8byte %[store_release];
    #2:  r1 = *(u64 *)(r10 - 8);
    #3:  r2 = r10;
    #4:  r2 += r1;
    #5:  r0 = 0;
    #6:  exit;

At #1, if the verifier doesn't remember that we wrote 8 to the stack,
then later at #4 we would be adding an unbounded scalar value to the
stack pointer, which would cause the program to be rejected:

  VERIFIER LOG:
  =============
...
  math between fp pointer and register with unbounded min value is not allowed

For easier CI integration, instead of using built-ins like
__atomic_{load,store}_n() which depend on the new
__BPF_FEATURE_LOAD_ACQ_STORE_REL pre-defined macro, manually craft
load-acquire/store-release instructions using __imm_insn(), as suggested
by Eduard.

All new tests depend on:

  (1) Clang major version >= 18, and
  (2) ENABLE_ATOMICS_TESTS is defined (currently implies -mcpu=v3 or
      v4), and
  (3) JIT supports load-acquire/store-release (currently arm64 and
      x86-64)

In .../progs/arena_atomics.c:

  /* 8-byte-aligned */
  __u8 __arena_global load_acquire8_value = 0x12;
  /* 1-byte hole */
  __u16 __arena_global load_acquire16_value = 0x1234;

That 1-byte hole in the .addr_space.1 ELF section caused clang-17 to
crash:

  fatal error: error in backend: unable to write nop sequence of 1 bytes

To work around such llvm-17 CI job failures, conditionally define
__arena_global variables as 64-bit if __clang_major__ < 18, to make sure
.addr_space.1 has no holes.  Ideally we should avoid compiling this file
using clang-17 at all (arena tests depend on
__BPF_FEATURE_ADDR_SPACE_CAST, and are skipped for llvm-17 anyway), but
that is a separate topic.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Peilin Ye <yepeilin@google.com>
Link: https://lore.kernel.org/r/1b46c6feaf0f1b6984d9ec80e500cc7383e9da1a.1741049567.git.yepeilin@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

perf test 11 hwmon fails on s390 with this error

 # ./perf test -Fv 11
 --- start ---
 ---- end ----
 11.1: Basic parsing test             : Ok
 --- start ---
 Testing 'temp_test_hwmon_event1'
 Using CPUID IBM,3931,704,A01,3.7,002f
 temp_test_hwmon_event1 -> hwmon_a_test_hwmon_pmu/temp_test_hwmon_event1/
 FAILED tests/hwmon_pmu.c:189 Unexpected config for
    'temp_test_hwmon_event1', 292470092988416 != 655361
 ---- end ----
 11.2: Parsing without PMU name       : FAILED!
 --- start ---
 Testing 'hwmon_a_test_hwmon_pmu/temp_test_hwmon_event1/'
 FAILED tests/hwmon_pmu.c:189 Unexpected config for
    'hwmon_a_test_hwmon_pmu/temp_test_hwmon_event1/',
    292470092988416 != 655361
 ---- end ----
 11.3: Parsing with PMU name          : FAILED!
 #

The root cause is in member test_event::config which is initialized
to 0xA0001 or 655361. During event parsing a long list event parsing
functions are called and end up with this gdb call stack:

 #0  hwmon_pmu__config_term (hwm=0x168dfd0, attr=0x3ffffff5ee8,
	term=0x168db60, err=0x3ffffff81c8) at util/hwmon_pmu.c:623
 #1  hwmon_pmu__config_terms (pmu=0x168dfd0, attr=0x3ffffff5ee8,
	terms=0x3ffffff5ea8, err=0x3ffffff81c8) at util/hwmon_pmu.c:662
 #2  0x00000000012f870c in perf_pmu__config_terms (pmu=0x168dfd0,
	attr=0x3ffffff5ee8, terms=0x3ffffff5ea8, zero=false,
	apply_hardcoded=false, err=0x3ffffff81c8) at util/pmu.c:1519
 #3  0x00000000012f88a4 in perf_pmu__config (pmu=0x168dfd0, attr=0x3ffffff5ee8,
	head_terms=0x3ffffff5ea8, apply_hardcoded=false, err=0x3ffffff81c8)
	at util/pmu.c:1545
 #4  0x00000000012680c4 in parse_events_add_pmu (parse_state=0x3ffffff7fb8,
	list=0x168dc00, pmu=0x168dfd0, const_parsed_terms=0x3ffffff6090,
	auto_merge_stats=true, alternate_hw_config=10)
	at util/parse-events.c:1508
 #5  0x00000000012684c6 in parse_events_multi_pmu_add (parse_state=0x3ffffff7fb8,
	event_name=0x168ec10 "temp_test_hwmon_event1", hw_config=10,
	const_parsed_terms=0x0, listp=0x3ffffff6230, loc_=0x3ffffff70e0)
	at util/parse-events.c:1592
 #6  0x00000000012f0e4e in parse_events_parse (_parse_state=0x3ffffff7fb8,
	scanner=0x16878c0) at util/parse-events.y:293
 #7  0x00000000012695a0 in parse_events__scanner (str=0x3ffffff81d8
	"temp_test_hwmon_event1", input=0x0, parse_state=0x3ffffff7fb8)
	at util/parse-events.c:1867
 #8  0x000000000126a1e8 in __parse_events (evlist=0x168b580,
	str=0x3ffffff81d8 "temp_test_hwmon_event1", pmu_filter=0x0,
	err=0x3ffffff81c8, fake_pmu=false, warn_if_reordered=true,
	fake_tp=false) at util/parse-events.c:2136
 #9  0x00000000011e36aa in parse_events (evlist=0x168b580,
	str=0x3ffffff81d8 "temp_test_hwmon_event1", err=0x3ffffff81c8)
	at /root/linux/tools/perf/util/parse-events.h:41
 #10 0x00000000011e3e64 in do_test (i=0, with_pmu=false, with_alias=false)
	at tests/hwmon_pmu.c:164
 #11 0x00000000011e422c in test__hwmon_pmu (with_pmu=false)
	at tests/hwmon_pmu.c:219
 #12 0x00000000011e431c in test__hwmon_pmu_without_pmu (test=0x1610368
	<suite.hwmon_pmu>, subtest=1) at tests/hwmon_pmu.c:23

where the attr::config is set to value 292470092988416 or 0x10a0000000000
in line 625 of file ./util/hwmon_pmu.c:

   attr->config = key.type_and_num;

However member key::type_and_num is defined as union and bit field:

   union hwmon_pmu_event_key {
        long type_and_num;
        struct {
                int num :16;
                enum hwmon_type type :8;
        };
   };

s390 is big endian and Intel is little endian architecture.
The events for the hwmon dummy pmu have num = 1 or num = 2 and
type is set to HWMON_TYPE_TEMP (which is 10).
On s390 this assignes member key::type_and_num the value of
0x10a0000000000 (which is 292470092988416) as shown in above
trace output.

Fix this and export the structure/union hwmon_pmu_event_key
so the test shares the same implementation as the event parsing
functions for union and bit fields. This should avoid
endianess issues on all platforms.

Output after:
 # ./perf test -F 11
 11.1: Basic parsing test         : Ok
 11.2: Parsing without PMU name   : Ok
 11.3: Parsing with PMU name      : Ok
 #

Fixes: 531ee0f ("perf test: Add hwmon "PMU" test")
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250131112400.568975-1-tmricht@linux.ibm.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Ian told me that there are many memory leaks in the hierarchy mode.  I
can easily reproduce it with the follwing command.

  $ make DEBUG=1 EXTRA_CFLAGS=-fsanitize=leak

  $ perf record --latency -g -- ./perf test -w thloop

  $ perf report -H --stdio
  ...
  Indirect leak of 168 byte(s) in 21 object(s) allocated from:
      #0 0x7f3414c16c65 in malloc ../../../../src/libsanitizer/lsan/lsan_interceptors.cpp:75
      #1 0x55ed3602346e in map__get util/map.h:189
      #2 0x55ed36024cc4 in hist_entry__init util/hist.c:476
      #3 0x55ed36025208 in hist_entry__new util/hist.c:588
      #4 0x55ed36027c05 in hierarchy_insert_entry util/hist.c:1587
      #5 0x55ed36027e2e in hists__hierarchy_insert_entry util/hist.c:1638
      #6 0x55ed36027fa4 in hists__collapse_insert_entry util/hist.c:1685
      #7 0x55ed360283e8 in hists__collapse_resort util/hist.c:1776
      #8 0x55ed35de0323 in report__collapse_hists /home/namhyung/project/linux/tools/perf/builtin-report.c:735
      #9 0x55ed35de15b4 in __cmd_report /home/namhyung/project/linux/tools/perf/builtin-report.c:1119
      #10 0x55ed35de43dc in cmd_report /home/namhyung/project/linux/tools/perf/builtin-report.c:1867
      #11 0x55ed35e66767 in run_builtin /home/namhyung/project/linux/tools/perf/perf.c:351
      #12 0x55ed35e66a0e in handle_internal_command /home/namhyung/project/linux/tools/perf/perf.c:404
      #13 0x55ed35e66b67 in run_argv /home/namhyung/project/linux/tools/perf/perf.c:448
      #14 0x55ed35e66eb0 in main /home/namhyung/project/linux/tools/perf/perf.c:556
      #15 0x7f340ac33d67 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
  ...

  $ perf report -H --stdio 2>&1 | grep -c '^Indirect leak'
  93

I found that hist_entry__delete() missed to release child entries in the
hierarchy tree (hroot_{in,out}).  It needs to iterate the child entries
and call hist_entry__delete() recursively.

After this change:

  $ perf report -H --stdio 2>&1 | grep -c '^Indirect leak'
  0

Reported-by: Ian Rogers <irogers@google.com>
Tested-by Thomas Falcon <thomas.falcon@intel.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250307061250.320849-2-namhyung@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

The env.pmu_mapping can be leaked when it reads data from a pipe on AMD.
For a pipe data, it reads the header data including pmu_mapping from
PERF_RECORD_HEADER_FEATURE runtime.  But it's already set in:

  perf_session__new()
    __perf_session__new()
      evlist__init_trace_event_sample_raw()
        evlist__has_amd_ibs()
          perf_env__nr_pmu_mappings()

Then it'll overwrite that when it processes the HEADER_FEATURE record.
Here's a report from address sanitizer.

  Direct leak of 2689 byte(s) in 1 object(s) allocated from:
    #0 0x7fed8f814596 in realloc ../../../../src/libsanitizer/lsan/lsan_interceptors.cpp:98
    #1 0x5595a7d416b1 in strbuf_grow util/strbuf.c:64
    #2 0x5595a7d414ef in strbuf_init util/strbuf.c:25
    #3 0x5595a7d0f4b7 in perf_env__read_pmu_mappings util/env.c:362
    #4 0x5595a7d12ab7 in perf_env__nr_pmu_mappings util/env.c:517
    #5 0x5595a7d89d2f in evlist__has_amd_ibs util/amd-sample-raw.c:315
    #6 0x5595a7d87fb2 in evlist__init_trace_event_sample_raw util/sample-raw.c:23
    #7 0x5595a7d7f893 in __perf_session__new util/session.c:179
    #8 0x5595a7b79572 in perf_session__new util/session.h:115
    #9 0x5595a7b7e9dc in cmd_report builtin-report.c:1603
    #10 0x5595a7c019eb in run_builtin perf.c:351
    #11 0x5595a7c01c92 in handle_internal_command perf.c:404
    #12 0x5595a7c01deb in run_argv perf.c:448
    #13 0x5595a7c02134 in main perf.c:556
    #14 0x7fed85833d67 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58

Let's free the existing pmu_mapping data if any.

Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Link: https://lore.kernel.org/r/20250311000416.817631-1-namhyung@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

When a bio with REQ_PREFLUSH is submitted to dm, __send_empty_flush()
generates a flush_bio with REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC,
which causes the flush_bio to be throttled by wbt_wait().

An example from v5.4, similar problem also exists in upstream:

    crash> bt 2091206
    PID: 2091206  TASK: ffff2050df92a300  CPU: 109  COMMAND: "kworker/u260:0"
     #0 [ffff800084a2f7f0] __switch_to at ffff80004008aeb8
     #1 [ffff800084a2f820] __schedule at ffff800040bfa0c4
     #2 [ffff800084a2f880] schedule at ffff800040bfa4b4
     #3 [ffff800084a2f8a0] io_schedule at ffff800040bfa9c4
     #4 [ffff800084a2f8c0] rq_qos_wait at ffff8000405925bc
     #5 [ffff800084a2f940] wbt_wait at ffff8000405bb3a0
     #6 [ffff800084a2f9a0] __rq_qos_throttle at ffff800040592254
     #7 [ffff800084a2f9c0] blk_mq_make_request at ffff80004057cf38
     #8 [ffff800084a2fa60] generic_make_request at ffff800040570138
     #9 [ffff800084a2fae0] submit_bio at ffff8000405703b4
    #10 [ffff800084a2fb50] xlog_write_iclog at ffff800001280834 [xfs]
    #11 [ffff800084a2fbb0] xlog_sync at ffff800001280c3c [xfs]
    #12 [ffff800084a2fbf0] xlog_state_release_iclog at ffff800001280df4 [xfs]
    #13 [ffff800084a2fc10] xlog_write at ffff80000128203c [xfs]
    #14 [ffff800084a2fcd0] xlog_cil_push at ffff8000012846dc [xfs]
    #15 [ffff800084a2fda0] xlog_cil_push_work at ffff800001284a2c [xfs]
    #16 [ffff800084a2fdb0] process_one_work at ffff800040111d08
    #17 [ffff800084a2fe00] worker_thread at ffff8000401121cc
    #18 [ffff800084a2fe70] kthread at ffff800040118de4

After commit 2def284 ("xfs: don't allow log IO to be throttled"),
the metadata submitted by xlog_write_iclog() should not be throttled.
But due to the existence of the dm layer, throttling flush_bio indirectly
causes the metadata bio to be throttled.

Fix this by conditionally adding REQ_IDLE to flush_bio.bi_opf, which makes
wbt_should_throttle() return false to avoid wbt_wait().

Signed-off-by: Jinliang Zheng <alexjlzheng@tencent.com>
Reviewed-by: Tianxiang Peng <txpeng@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

…e probe

The spin lock tx_handling_spinlock in struct m_can_classdev is not
being initialized. This leads the following spinlock bad magic
complaint from the kernel, eg. when trying to send CAN frames with
cansend from can-utils:

| BUG: spinlock bad magic on CPU#0, cansend/95
|  lock: 0xff60000002ec1010, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
| CPU: 0 UID: 0 PID: 95 Comm: cansend Not tainted 6.15.0-rc3-00032-ga79be02bba5c #5 NONE
| Hardware name: MachineWare SIM-V (DT)
| Call Trace:
| [<ffffffff800133e0>] dump_backtrace+0x1c/0x24
| [<ffffffff800022f2>] show_stack+0x28/0x34
| [<ffffffff8000de3e>] dump_stack_lvl+0x4a/0x68
| [<ffffffff8000de70>] dump_stack+0x14/0x1c
| [<ffffffff80003134>] spin_dump+0x62/0x6e
| [<ffffffff800883ba>] do_raw_spin_lock+0xd0/0x142
| [<ffffffff807a6fcc>] _raw_spin_lock_irqsave+0x20/0x2c
| [<ffffffff80536dba>] m_can_start_xmit+0x90/0x34a
| [<ffffffff806148b0>] dev_hard_start_xmit+0xa6/0xee
| [<ffffffff8065b730>] sch_direct_xmit+0x114/0x292
| [<ffffffff80614e2a>] __dev_queue_xmit+0x3b0/0xaa8
| [<ffffffff8073b8fa>] can_send+0xc6/0x242
| [<ffffffff8073d1c0>] raw_sendmsg+0x1a8/0x36c
| [<ffffffff805ebf06>] sock_write_iter+0x9a/0xee
| [<ffffffff801d06ea>] vfs_write+0x184/0x3a6
| [<ffffffff801d0a88>] ksys_write+0xa0/0xc0
| [<ffffffff801d0abc>] __riscv_sys_write+0x14/0x1c
| [<ffffffff8079ebf8>] do_trap_ecall_u+0x168/0x212
| [<ffffffff807a830a>] handle_exception+0x146/0x152

Initializing the spin lock in m_can_class_allocate_dev solves that
problem.

Fixes: 1fa80e2 ("can: m_can: Introduce a tx_fifo_in_flight counter")
Signed-off-by: Antonios Salios <antonios@mwa.re>
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://patch.msgid.link/20250425111744.37604-2-antonios@mwa.re
Reviewed-by: Markus Schneider-Pargmann <msp@baylibre.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

…xit()

scheduler's ->exit() is called with queue frozen and elevator lock is held, and
wbt_enable_default() can't be called with queue frozen, otherwise the
following lockdep warning is triggered:

	#6 (&q->rq_qos_mutex){+.+.}-{4:4}:
	#5 (&eq->sysfs_lock){+.+.}-{4:4}:
	#4 (&q->elevator_lock){+.+.}-{4:4}:
	#3 (&q->q_usage_counter(io)#3){++++}-{0:0}:
	#2 (fs_reclaim){+.+.}-{0:0}:
	#1 (&sb->s_type->i_mutex_key#3){+.+.}-{4:4}:
	#0 (&q->debugfs_mutex){+.+.}-{4:4}:

Fix the issue by moving wbt_enable_default() out of bfq's exit(), and
call it from elevator_change_done().

Meantime add disk->rqos_state_mutex for covering wbt state change, which
matches the purpose more than ->elevator_lock.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250505141805.2751237-26-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

ACPICA commit 1c28da2242783579d59767617121035dafba18c3

This was originally done in NetBSD:
NetBSD/src@b69d1ac
and is the correct alternative to the smattering of `memcpy`s I
previously contributed to this repository.

This also sidesteps the newly strict checks added in UBSAN:
llvm/llvm-project@7926744

Before this change we see the following UBSAN stack trace in Fuchsia:

  #0    0x000021afcfdeca5e in acpi_rs_get_address_common(struct acpi_resource*, union aml_resource*) ../../third_party/acpica/source/components/resources/rsaddr.c:329 <platform-bus-x86.so>+0x6aca5e
  #1.2  0x000021982bc4af3c in ubsan_get_stack_trace() compiler-rt/lib/ubsan/ubsan_diag.cpp:41 <libclang_rt.asan.so>+0x41f3c
  #1.1  0x000021982bc4af3c in maybe_print_stack_trace() compiler-rt/lib/ubsan/ubsan_diag.cpp:51 <libclang_rt.asan.so>+0x41f3c
  #1    0x000021982bc4af3c in ~scoped_report() compiler-rt/lib/ubsan/ubsan_diag.cpp:395 <libclang_rt.asan.so>+0x41f3c
  #2    0x000021982bc4bb6f in handletype_mismatch_impl() compiler-rt/lib/ubsan/ubsan_handlers.cpp:137 <libclang_rt.asan.so>+0x42b6f
  #3    0x000021982bc4b723 in __ubsan_handle_type_mismatch_v1 compiler-rt/lib/ubsan/ubsan_handlers.cpp:142 <libclang_rt.asan.so>+0x42723
  #4    0x000021afcfdeca5e in acpi_rs_get_address_common(struct acpi_resource*, union aml_resource*) ../../third_party/acpica/source/components/resources/rsaddr.c:329 <platform-bus-x86.so>+0x6aca5e
  #5    0x000021afcfdf2089 in acpi_rs_convert_aml_to_resource(struct acpi_resource*, union aml_resource*, struct acpi_rsconvert_info*) ../../third_party/acpica/source/components/resources/rsmisc.c:355 <platform-bus-x86.so>+0x6b2089
  #6    0x000021afcfded169 in acpi_rs_convert_aml_to_resources(u8*, u32, u32, u8, void**) ../../third_party/acpica/source/components/resources/rslist.c:137 <platform-bus-x86.so>+0x6ad169
  #7    0x000021afcfe2d24a in acpi_ut_walk_aml_resources(struct acpi_walk_state*, u8*, acpi_size, acpi_walk_aml_callback, void**) ../../third_party/acpica/source/components/utilities/utresrc.c:237 <platform-bus-x86.so>+0x6ed24a
  #8    0x000021afcfde66b7 in acpi_rs_create_resource_list(union acpi_operand_object*, struct acpi_buffer*) ../../third_party/acpica/source/components/resources/rscreate.c:199 <platform-bus-x86.so>+0x6a66b7
  #9    0x000021afcfdf6979 in acpi_rs_get_method_data(acpi_handle, const char*, struct acpi_buffer*) ../../third_party/acpica/source/components/resources/rsutils.c:770 <platform-bus-x86.so>+0x6b6979
  #10   0x000021afcfdf708f in acpi_walk_resources(acpi_handle, char*, acpi_walk_resource_callback, void*) ../../third_party/acpica/source/components/resources/rsxface.c:731 <platform-bus-x86.so>+0x6b708f
  #11   0x000021afcfa95dcf in acpi::acpi_impl::walk_resources(acpi::acpi_impl*, acpi_handle, const char*, acpi::Acpi::resources_callable) ../../src/devices/board/lib/acpi/acpi-impl.cc:41 <platform-bus-x86.so>+0x355dcf
  #12   0x000021afcfaa8278 in acpi::device_builder::gather_resources(acpi::device_builder*, acpi::Acpi*, fidl::any_arena&, acpi::Manager*, acpi::device_builder::gather_resources_callback) ../../src/devices/board/lib/acpi/device-builder.cc:84 <platform-bus-x86.so>+0x368278
  #13   0x000021afcfbddb87 in acpi::Manager::configure_discovered_devices(acpi::Manager*) ../../src/devices/board/lib/acpi/manager.cc:75 <platform-bus-x86.so>+0x49db87
  #14   0x000021afcf99091d in publish_acpi_devices(acpi::Manager*, zx_device_t*, zx_device_t*) ../../src/devices/board/drivers/x86/acpi-nswalk.cc:95 <platform-bus-x86.so>+0x25091d
  #15   0x000021afcf9c1d4e in x86::X86::do_init(x86::X86*) ../../src/devices/board/drivers/x86/x86.cc:60 <platform-bus-x86.so>+0x281d4e
  #16   0x000021afcf9e33ad in λ(x86::X86::ddk_init::(anon class)*) ../../src/devices/board/drivers/x86/x86.cc:77 <platform-bus-x86.so>+0x2a33ad
  #17   0x000021afcf9e313e in fit::internal::target<(lambda at../../src/devices/board/drivers/x86/x86.cc:76:19), false, false, std::__2::allocator<std::byte>, void>::invoke(void*) ../../sdk/lib/fit/include/lib/fit/internal/function.h:183 <platform-bus-x86.so>+0x2a313e
  #18   0x000021afcfbab4c7 in fit::internal::function_base<16UL, false, void(), std::__2::allocator<std::byte>>::invoke(const fit::internal::function_base<16UL, false, void (), std::__2::allocator<std::byte> >*) ../../sdk/lib/fit/include/lib/fit/internal/function.h:522 <platform-bus-x86.so>+0x46b4c7
  #19   0x000021afcfbab342 in fit::function_impl<16UL, false, void(), std::__2::allocator<std::byte>>::operator()(const fit::function_impl<16UL, false, void (), std::__2::allocator<std::byte> >*) ../../sdk/lib/fit/include/lib/fit/function.h:315 <platform-bus-x86.so>+0x46b342
  #20   0x000021afcfcd98c3 in async::internal::retained_task::Handler(async_dispatcher_t*, async_task_t*, zx_status_t) ../../sdk/lib/async/task.cc:24 <platform-bus-x86.so>+0x5998c3
  #21   0x00002290f9924616 in λ(const driver_runtime::Dispatcher::post_task::(anon class)*, std::__2::unique_ptr<driver_runtime::callback_request, std::__2::default_delete<driver_runtime::callback_request> >, zx_status_t) ../../src/devices/bin/driver_runtime/dispatcher.cc:789 <libdriver_runtime.so>+0x10a616
  #22   0x00002290f9924323 in fit::internal::target<(lambda at../../src/devices/bin/driver_runtime/dispatcher.cc:788:7), true, false, std::__2::allocator<std::byte>, void, std::__2::unique_ptr<driver_runtime::callback_request, std::__2::default_delete<driver_runtime::callback_request>>, int>::invoke(void*, std::__2::unique_ptr<driver_runtime::callback_request, std::__2::default_delete<driver_runtime::callback_request> >, int) ../../sdk/lib/fit/include/lib/fit/internal/function.h:128 <libdriver_runtime.so>+0x10a323
  #23   0x00002290f9904b76 in fit::internal::function_base<24UL, true, void(std::__2::unique_ptr<driver_runtime::callback_request, std::__2::default_delete<driver_runtime::callback_request>>, int), std::__2::allocator<std::byte>>::invoke(const fit::internal::function_base<24UL, true, void (std::__2::unique_ptr<driver_runtime::callback_request, std::__2::default_delete<driver_runtime::callback_request> >, int), std::__2::allocator<std::byte> >*, std::__2::unique_ptr<driver_runtime::callback_request, std::__2::default_delete<driver_runtime::callback_request> >, int) ../../sdk/lib/fit/include/lib/fit/internal/function.h:522 <libdriver_runtime.so>+0xeab76
  #24   0x00002290f9904831 in fit::callback_impl<24UL, true, void(std::__2::unique_ptr<driver_runtime::callback_request, std::__2::default_delete<driver_runtime::callback_request>>, int), std::__2::allocator<std::byte>>::operator()(fit::callback_impl<24UL, true, void (std::__2::unique_ptr<driver_runtime::callback_request, std::__2::default_delete<driver_runtime::callback_request> >, int), std::__2::allocator<std::byte> >*, std::__2::unique_ptr<driver_runtime::callback_request, std::__2::default_delete<driver_runtime::callback_request> >, int) ../../sdk/lib/fit/include/lib/fit/function.h:471 <libdriver_runtime.so>+0xea831
  #25   0x00002290f98d5adc in driver_runtime::callback_request::Call(driver_runtime::callback_request*, std::__2::unique_ptr<driver_runtime::callback_request, std::__2::default_delete<driver_runtime::callback_request> >, zx_status_t) ../../src/devices/bin/driver_runtime/callback_request.h:74 <libdriver_runtime.so>+0xbbadc
  #26   0x00002290f98e1e58 in driver_runtime::Dispatcher::dispatch_callback(driver_runtime::Dispatcher*, std::__2::unique_ptr<driver_runtime::callback_request, std::__2::default_delete<driver_runtime::callback_request> >) ../../src/devices/bin/driver_runtime/dispatcher.cc:1248 <libdriver_runtime.so>+0xc7e58
  #27   0x00002290f98e4159 in driver_runtime::Dispatcher::dispatch_callbacks(driver_runtime::Dispatcher*, std::__2::unique_ptr<driver_runtime::Dispatcher::event_waiter, std::__2::default_delete<driver_runtime::Dispatcher::event_waiter> >, fbl::ref_ptr<driver_runtime::Dispatcher>) ../../src/devices/bin/driver_runtime/dispatcher.cc:1308 <libdriver_runtime.so>+0xca159
  #28   0x00002290f9918414 in λ(const driver_runtime::Dispatcher::create_with_adder::(anon class)*, std::__2::unique_ptr<driver_runtime::Dispatcher::event_waiter, std::__2::default_delete<driver_runtime::Dispatcher::event_waiter> >, fbl::ref_ptr<driver_runtime::Dispatcher>) ../../src/devices/bin/driver_runtime/dispatcher.cc:353 <libdriver_runtime.so>+0xfe414
  #29   0x00002290f991812d in fit::internal::target<(lambda at../../src/devices/bin/driver_runtime/dispatcher.cc:351:7), true, false, std::__2::allocator<std::byte>, void, std::__2::unique_ptr<driver_runtime::Dispatcher::event_waiter, std::__2::default_delete<driver_runtime::Dispatcher::event_waiter>>, fbl::ref_ptr<driver_runtime::Dispatcher>>::invoke(void*, std::__2::unique_ptr<driver_runtime::Dispatcher::event_waiter, std::__2::default_delete<driver_runtime::Dispatcher::event_waiter> >, fbl::ref_ptr<driver_runtime::Dispatcher>) ../../sdk/lib/fit/include/lib/fit/internal/function.h:128 <libdriver_runtime.so>+0xfe12d
  #30   0x00002290f9906fc7 in fit::internal::function_base<8UL, true, void(std::__2::unique_ptr<driver_runtime::Dispatcher::event_waiter, std::__2::default_delete<driver_runtime::Dispatcher::event_waiter>>, fbl::ref_ptr<driver_runtime::Dispatcher>), std::__2::allocator<std::byte>>::invoke(const fit::internal::function_base<8UL, true, void (std::__2::unique_ptr<driver_runtime::Dispatcher::event_waiter, std::__2::default_delete<driver_runtime::Dispatcher::event_waiter> >, fbl::ref_ptr<driver_runtime::Dispatcher>), std::__2::allocator<std::byte> >*, std::__2::unique_ptr<driver_runtime::Dispatcher::event_waiter, std::__2::default_delete<driver_runtime::Dispatcher::event_waiter> >, fbl::ref_ptr<driver_runtime::Dispatcher>) ../../sdk/lib/fit/include/lib/fit/internal/function.h:522 <libdriver_runtime.so>+0xecfc7
  #31   0x00002290f9906c66 in fit::function_impl<8UL, true, void(std::__2::unique_ptr<driver_runtime::Dispatcher::event_waiter, std::__2::default_delete<driver_runtime::Dispatcher::event_waiter>>, fbl::ref_ptr<driver_runtime::Dispatcher>), std::__2::allocator<std::byte>>::operator()(const fit::function_impl<8UL, true, void (std::__2::unique_ptr<driver_runtime::Dispatcher::event_waiter, std::__2::default_delete<driver_runtime::Dispatcher::event_waiter> >, fbl::ref_ptr<driver_runtime::Dispatcher>), std::__2::allocator<std::byte> >*, std::__2::unique_ptr<driver_runtime::Dispatcher::event_waiter, std::__2::default_delete<driver_runtime::Dispatcher::event_waiter> >, fbl::ref_ptr<driver_runtime::Dispatcher>) ../../sdk/lib/fit/include/lib/fit/function.h:315 <libdriver_runtime.so>+0xecc66
  #32   0x00002290f98e73d9 in driver_runtime::Dispatcher::event_waiter::invoke_callback(driver_runtime::Dispatcher::event_waiter*, std::__2::unique_ptr<driver_runtime::Dispatcher::event_waiter, std::__2::default_delete<driver_runtime::Dispatcher::event_waiter> >, fbl::ref_ptr<driver_runtime::Dispatcher>) ../../src/devices/bin/driver_runtime/dispatcher.h:543 <libdriver_runtime.so>+0xcd3d9
  #33   0x00002290f98e700d in driver_runtime::Dispatcher::event_waiter::handle_event(std::__2::unique_ptr<driver_runtime::Dispatcher::event_waiter, std::__2::default_delete<driver_runtime::Dispatcher::event_waiter> >, async_dispatcher_t*, async::wait_base*, zx_status_t, zx_packet_signal_t const*) ../../src/devices/bin/driver_runtime/dispatcher.cc:1442 <libdriver_runtime.so>+0xcd00d
  #34   0x00002290f9918983 in async_loop_owned_event_handler<driver_runtime::Dispatcher::event_waiter>::handle_event(async_loop_owned_event_handler<driver_runtime::Dispatcher::event_waiter>*, async_dispatcher_t*, async::wait_base*, zx_status_t, zx_packet_signal_t const*) ../../src/devices/bin/driver_runtime/async_loop_owned_event_handler.h:59 <libdriver_runtime.so>+0xfe983
  #35   0x00002290f9918b9e in async::wait_method<async_loop_owned_event_handler<driver_runtime::Dispatcher::event_waiter>, &async_loop_owned_event_handler<driver_runtime::Dispatcher::event_waiter>::handle_event>::call_handler(async_dispatcher_t*, async_wait_t*, zx_status_t, zx_packet_signal_t const*) ../../sdk/lib/async/include/lib/async/cpp/wait.h:201 <libdriver_runtime.so>+0xfeb9e
  #36   0x00002290f99bf509 in async_loop_dispatch_wait(async_loop_t*, async_wait_t*, zx_status_t, zx_packet_signal_t const*) ../../sdk/lib/async-loop/loop.c:394 <libdriver_runtime.so>+0x1a5509
  #37   0x00002290f99b9958 in async_loop_run_once(async_loop_t*, zx_time_t) ../../sdk/lib/async-loop/loop.c:343 <libdriver_runtime.so>+0x19f958
  #38   0x00002290f99b9247 in async_loop_run(async_loop_t*, zx_time_t, _Bool) ../../sdk/lib/async-loop/loop.c:301 <libdriver_runtime.so>+0x19f247
  #39   0x00002290f99ba962 in async_loop_run_thread(void*) ../../sdk/lib/async-loop/loop.c:860 <libdriver_runtime.so>+0x1a0962
  #40   0x000041afd176ef30 in start_c11(void*) ../../zircon/third_party/ulib/musl/pthread/pthread_create.c:63 <libc.so>+0x84f30
  #41   0x000041afd18a448d in thread_trampoline(uintptr_t, uintptr_t) ../../zircon/system/ulib/runtime/thread.cc:100 <libc.so>+0x1ba48d

Link: acpica/acpica@1c28da22
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://patch.msgid.link/4664267.LvFx2qVVIh@rjwysocki.net
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
[ rjw: Pick up the tag from Tamir ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Intel TDX protects guest VM's from malicious host and certain physical
attacks.  TDX introduces a new operation mode, Secure Arbitration Mode
(SEAM) to isolate and protect guest VM's.  A TDX guest VM runs in SEAM and,
unlike VMX, direct control and interaction with the guest by the host VMM
is not possible.  Instead, Intel TDX Module, which also runs in SEAM,
provides a SEAMCALL API.

The SEAMCALL that provides the ability to enter a guest is TDH.VP.ENTER.
The TDX Module processes TDH.VP.ENTER, and enters the guest via VMX
VMLAUNCH/VMRESUME instructions.  When a guest VM-exit requires host VMM
interaction, the TDH.VP.ENTER SEAMCALL returns to the host VMM (KVM).

Add tdh_vp_enter() to wrap the SEAMCALL invocation of TDH.VP.ENTER;
tdh_vp_enter() needs to be noinstr because VM entry in KVM is noinstr
as well, which is for two reasons:
* marking the area as CT_STATE_GUEST via guest_state_enter_irqoff() and
  guest_state_exit_irqoff()
* IRET must be avoided between VM-exit and NMI handling, in order to
  avoid prematurely releasing the NMI inhibit.

TDH.VP.ENTER is different from other SEAMCALLs in several ways: it
uses more arguments, and after it returns some host state may need to be
restored.  Therefore tdh_vp_enter() uses __seamcall_saved_ret() instead of
__seamcall_ret(); since it is the only caller of __seamcall_saved_ret(),
it can be made noinstr also.

TDH.VP.ENTER arguments are passed through General Purpose Registers (GPRs).
For the special case of the TD guest invoking TDG.VP.VMCALL, nearly any GPR
can be used, as well as XMM0 to XMM15. Notably, RBP is not used, and Linux
mandates the TDX Module feature NO_RBP_MOD, which is enforced elsewhere.
Additionally, XMM registers are not required for the existing Guest
Hypervisor Communication Interface and are handled by existing KVM code
should they be modified by the guest.

There are 2 input formats and 5 output formats for TDH.VP.ENTER arguments.
Input #1 : Initial entry or following a previous async. TD Exit
Input #2 : Following a previous TDCALL(TDG.VP.VMCALL)
Output #1 : On Error (No TD Entry)
Output #2 : Async. Exits with a VMX Architectural Exit Reason
Output #3 : Async. Exits with a non-VMX TD Exit Status
Output #4 : Async. Exits with Cross-TD Exit Details
Output #5 : On TDCALL(TDG.VP.VMCALL)

Currently, to keep things simple, the wrapper function does not attempt
to support different formats, and just passes all the GPRs that could be
used.  The GPR values are held by KVM in the area set aside for guest
GPRs.  KVM code uses the guest GPR area (vcpu->arch.regs[]) to set up for
or process results of tdh_vp_enter().

Therefore changing tdh_vp_enter() to use more complex argument formats
would also alter the way KVM code interacts with tdh_vp_enter().

Signed-off-by: Kai Huang <kai.huang@intel.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Message-ID: <20241121201448.36170-2-adrian.hunter@intel.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Running a modified trace-cmd record --nosplice where it does a mmap of the
ring buffer when '--nosplice' is set, caused the following lockdep splat:

 ======================================================
 WARNING: possible circular locking dependency detected
 6.15.0-rc7-test-00002-gfb7d03d8a82f #551 Not tainted
 ------------------------------------------------------
 trace-cmd/1113 is trying to acquire lock:
 ffff888100062888 (&buffer->mutex){+.+.}-{4:4}, at: ring_buffer_map+0x11c/0xe70

 but task is already holding lock:
 ffff888100a5f9f8 (&cpu_buffer->mapping_lock){+.+.}-{4:4}, at: ring_buffer_map+0xcf/0xe70

 which lock already depends on the new lock.

 the existing dependency chain (in reverse order) is:

 -> #5 (&cpu_buffer->mapping_lock){+.+.}-{4:4}:
        __mutex_lock+0x192/0x18c0
        ring_buffer_map+0xcf/0xe70
        tracing_buffers_mmap+0x1c4/0x3b0
        __mmap_region+0xd8d/0x1f70
        do_mmap+0x9d7/0x1010
        vm_mmap_pgoff+0x20b/0x390
        ksys_mmap_pgoff+0x2e9/0x440
        do_syscall_64+0x79/0x1c0
        entry_SYSCALL_64_after_hwframe+0x76/0x7e

 -> #4 (&mm->mmap_lock){++++}-{4:4}:
        __might_fault+0xa5/0x110
        _copy_to_user+0x22/0x80
        _perf_ioctl+0x61b/0x1b70
        perf_ioctl+0x62/0x90
        __x64_sys_ioctl+0x134/0x190
        do_syscall_64+0x79/0x1c0
        entry_SYSCALL_64_after_hwframe+0x76/0x7e

 -> #3 (&cpuctx_mutex){+.+.}-{4:4}:
        __mutex_lock+0x192/0x18c0
        perf_event_init_cpu+0x325/0x7c0
        perf_event_init+0x52a/0x5b0
        start_kernel+0x263/0x3e0
        x86_64_start_reservations+0x24/0x30
        x86_64_start_kernel+0x95/0xa0
        common_startup_64+0x13e/0x141

 -> #2 (pmus_lock){+.+.}-{4:4}:
        __mutex_lock+0x192/0x18c0
        perf_event_init_cpu+0xb7/0x7c0
        cpuhp_invoke_callback+0x2c0/0x1030
        __cpuhp_invoke_callback_range+0xbf/0x1f0
        _cpu_up+0x2e7/0x690
        cpu_up+0x117/0x170
        cpuhp_bringup_mask+0xd5/0x120
        bringup_nonboot_cpus+0x13d/0x170
        smp_init+0x2b/0xf0
        kernel_init_freeable+0x441/0x6d0
        kernel_init+0x1e/0x160
        ret_from_fork+0x34/0x70
        ret_from_fork_asm+0x1a/0x30

 -> #1 (cpu_hotplug_lock){++++}-{0:0}:
        cpus_read_lock+0x2a/0xd0
        ring_buffer_resize+0x610/0x14e0
        __tracing_resize_ring_buffer.part.0+0x42/0x120
        tracing_set_tracer+0x7bd/0xa80
        tracing_set_trace_write+0x132/0x1e0
        vfs_write+0x21c/0xe80
        ksys_write+0xf9/0x1c0
        do_syscall_64+0x79/0x1c0
        entry_SYSCALL_64_after_hwframe+0x76/0x7e

 -> #0 (&buffer->mutex){+.+.}-{4:4}:
        __lock_acquire+0x1405/0x2210
        lock_acquire+0x174/0x310
        __mutex_lock+0x192/0x18c0
        ring_buffer_map+0x11c/0xe70
        tracing_buffers_mmap+0x1c4/0x3b0
        __mmap_region+0xd8d/0x1f70
        do_mmap+0x9d7/0x1010
        vm_mmap_pgoff+0x20b/0x390
        ksys_mmap_pgoff+0x2e9/0x440
        do_syscall_64+0x79/0x1c0
        entry_SYSCALL_64_after_hwframe+0x76/0x7e

 other info that might help us debug this:

 Chain exists of:
   &buffer->mutex --> &mm->mmap_lock --> &cpu_buffer->mapping_lock

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(&cpu_buffer->mapping_lock);
                                lock(&mm->mmap_lock);
                                lock(&cpu_buffer->mapping_lock);
   lock(&buffer->mutex);

  *** DEADLOCK ***

 2 locks held by trace-cmd/1113:
  #0: ffff888106b847e0 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x192/0x390
  #1: ffff888100a5f9f8 (&cpu_buffer->mapping_lock){+.+.}-{4:4}, at: ring_buffer_map+0xcf/0xe70

 stack backtrace:
 CPU: 5 UID: 0 PID: 1113 Comm: trace-cmd Not tainted 6.15.0-rc7-test-00002-gfb7d03d8a82f #551 PREEMPT
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
 Call Trace:
  <TASK>
  dump_stack_lvl+0x6e/0xa0
  print_circular_bug.cold+0x178/0x1be
  check_noncircular+0x146/0x160
  __lock_acquire+0x1405/0x2210
  lock_acquire+0x174/0x310
  ? ring_buffer_map+0x11c/0xe70
  ? ring_buffer_map+0x11c/0xe70
  ? __mutex_lock+0x169/0x18c0
  __mutex_lock+0x192/0x18c0
  ? ring_buffer_map+0x11c/0xe70
  ? ring_buffer_map+0x11c/0xe70
  ? function_trace_call+0x296/0x370
  ? __pfx___mutex_lock+0x10/0x10
  ? __pfx_function_trace_call+0x10/0x10
  ? __pfx___mutex_lock+0x10/0x10
  ? _raw_spin_unlock+0x2d/0x50
  ? ring_buffer_map+0x11c/0xe70
  ? ring_buffer_map+0x11c/0xe70
  ? __mutex_lock+0x5/0x18c0
  ring_buffer_map+0x11c/0xe70
  ? do_raw_spin_lock+0x12d/0x270
  ? find_held_lock+0x2b/0x80
  ? _raw_spin_unlock+0x2d/0x50
  ? rcu_is_watching+0x15/0xb0
  ? _raw_spin_unlock+0x2d/0x50
  ? trace_preempt_on+0xd0/0x110
  tracing_buffers_mmap+0x1c4/0x3b0
  __mmap_region+0xd8d/0x1f70
  ? ring_buffer_lock_reserve+0x99/0xff0
  ? __pfx___mmap_region+0x10/0x10
  ? ring_buffer_lock_reserve+0x99/0xff0
  ? __pfx_ring_buffer_lock_reserve+0x10/0x10
  ? __pfx_ring_buffer_lock_reserve+0x10/0x10
  ? bpf_lsm_mmap_addr+0x4/0x10
  ? security_mmap_addr+0x46/0xd0
  ? lock_is_held_type+0xd9/0x130
  do_mmap+0x9d7/0x1010
  ? 0xffffffffc0370095
  ? __pfx_do_mmap+0x10/0x10
  vm_mmap_pgoff+0x20b/0x390
  ? __pfx_vm_mmap_pgoff+0x10/0x10
  ? 0xffffffffc0370095
  ksys_mmap_pgoff+0x2e9/0x440
  do_syscall_64+0x79/0x1c0
  entry_SYSCALL_64_after_hwframe+0x76/0x7e
 RIP: 0033:0x7fb0963a7de2
 Code: 00 00 00 0f 1f 44 00 00 41 f7 c1 ff 0f 00 00 75 27 55 89 cd 53 48 89 fb 48 85 ff 74 3b 41 89 ea 48 89 df b8 09 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 76 5b 5d c3 0f 1f 00 48 8b 05 e1 9f 0d 00 64
 RSP: 002b:00007ffdcc8fb878 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fb0963a7de2
 RDX: 0000000000000001 RSI: 0000000000001000 RDI: 0000000000000000
 RBP: 0000000000000001 R08: 0000000000000006 R09: 0000000000000000
 R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000
 R13: 00007ffdcc8fbe68 R14: 00007fb096628000 R15: 00005633e01a5c90
  </TASK>

The issue is that cpus_read_lock() is taken within buffer->mutex. The
memory mapped pages are taken with the mmap_lock held. The buffer->mutex
is taken within the cpu_buffer->mapping_lock. There's quite a chain with
all these locks, where the deadlock can be fixed by moving the
cpus_read_lock() outside the taking of the buffer->mutex.

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Vincent Donnefort <vdonnefort@google.com>
Link: https://lore.kernel.org/20250527105820.0f45d045@gandalf.local.home
Fixes: 117c392 ("ring-buffer: Introducing ring-buffer mapping functions")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Despite the fact that several lockdep-related checks are skipped when
calling trylock* versions of the locking primitives, for example
mutex_trylock, each time the mutex is acquired, a held_lock is still
placed onto the lockdep stack by __lock_acquire() which is called
regardless of whether the trylock* or regular locking API was used.

This means that if the caller successfully acquires more than
MAX_LOCK_DEPTH locks of the same class, even when using mutex_trylock,
lockdep will still complain that the maximum depth of the held lock stack
has been reached and disable itself.

For example, the following error currently occurs in the ARM version
of KVM, once the code tries to lock all vCPUs of a VM configured with more
than MAX_LOCK_DEPTH vCPUs, a situation that can easily happen on modern
systems, where having more than 48 CPUs is common, and it's also common to
run VMs that have vCPU counts approaching that number:

[  328.171264] BUG: MAX_LOCK_DEPTH too low!
[  328.175227] turning off the locking correctness validator.
[  328.180726] Please attach the output of /proc/lock_stat to the bug report
[  328.187531] depth: 48  max: 48!
[  328.190678] 48 locks held by qemu-kvm/11664:
[  328.194957]  #0: ffff800086de5ba0 (&kvm->lock){+.+.}-{3:3}, at: kvm_ioctl_create_device+0x174/0x5b0
[  328.204048]  #1: ffff0800e78800b8 (&vcpu->mutex){+.+.}-{3:3}, at: lock_all_vcpus+0x16c/0x2a0
[  328.212521]  #2: ffff07ffeee51e98 (&vcpu->mutex){+.+.}-{3:3}, at: lock_all_vcpus+0x16c/0x2a0
[  328.220991]  #3: ffff0800dc7d80b8 (&vcpu->mutex){+.+.}-{3:3}, at: lock_all_vcpus+0x16c/0x2a0
[  328.229463]  #4: ffff07ffe0c980b8 (&vcpu->mutex){+.+.}-{3:3}, at: lock_all_vcpus+0x16c/0x2a0
[  328.237934]  #5: ffff0800a3883c78 (&vcpu->mutex){+.+.}-{3:3}, at: lock_all_vcpus+0x16c/0x2a0
[  328.246405]  #6: ffff07fffbe480b8 (&vcpu->mutex){+.+.}-{3:3}, at: lock_all_vcpus+0x16c/0x2a0

Luckily, in all instances that require locking all vCPUs, the
'kvm->lock' is taken a priori, and that fact makes it possible to use
the little known feature of lockdep, called a 'nest_lock', to avoid this
warning and subsequent lockdep self-disablement.

The action of 'nested lock' being provided to lockdep's lock_acquire(),
causes the lockdep to detect that the top of the held lock stack contains
a lock of the same class and then increment its reference counter instead
of pushing a new held_lock item onto that stack.

See __lock_acquire for more information.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Message-ID: <20250512180407.659015-2-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Use kvm_trylock_all_vcpus instead of a custom implementation when locking
all vCPUs of a VM, to avoid triggering a lockdep warning, in the case in
which the VM is configured to have more than MAX_LOCK_DEPTH vCPUs.

This fixes the following false lockdep warning:

[  328.171264] BUG: MAX_LOCK_DEPTH too low!
[  328.175227] turning off the locking correctness validator.
[  328.180726] Please attach the output of /proc/lock_stat to the bug report
[  328.187531] depth: 48  max: 48!
[  328.190678] 48 locks held by qemu-kvm/11664:
[  328.194957]  #0: ffff800086de5ba0 (&kvm->lock){+.+.}-{3:3}, at: kvm_ioctl_create_device+0x174/0x5b0
[  328.204048]  #1: ffff0800e78800b8 (&vcpu->mutex){+.+.}-{3:3}, at: lock_all_vcpus+0x16c/0x2a0
[  328.212521]  #2: ffff07ffeee51e98 (&vcpu->mutex){+.+.}-{3:3}, at: lock_all_vcpus+0x16c/0x2a0
[  328.220991]  #3: ffff0800dc7d80b8 (&vcpu->mutex){+.+.}-{3:3}, at: lock_all_vcpus+0x16c/0x2a0
[  328.229463]  #4: ffff07ffe0c980b8 (&vcpu->mutex){+.+.}-{3:3}, at: lock_all_vcpus+0x16c/0x2a0
[  328.237934]  #5: ffff0800a3883c78 (&vcpu->mutex){+.+.}-{3:3}, at: lock_all_vcpus+0x16c/0x2a0
[  328.246405]  #6: ffff07fffbe480b8 (&vcpu->mutex){+.+.}-{3:3}, at: lock_all_vcpus+0x16c/0x2a0

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Message-ID: <20250512180407.659015-6-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

When reconnecting a channel in smb2_reconnect_server(), a dummy tcon
is passed down to smb2_reconnect() with ->query_interface
uninitialized, so we can't call queue_delayed_work() on it.

Fix the following warning by ensuring that we're queueing the delayed
worker from correct tcon.

WARNING: CPU: 4 PID: 1126 at kernel/workqueue.c:2498 __queue_delayed_work+0x1d2/0x200
Modules linked in: cifs cifs_arc4 nls_ucs2_utils cifs_md4 [last unloaded: cifs]
CPU: 4 UID: 0 PID: 1126 Comm: kworker/4:0 Not tainted 6.16.0-rc3 #5 PREEMPT(voluntary)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-4.fc42 04/01/2014
Workqueue: cifsiod smb2_reconnect_server [cifs]
RIP: 0010:__queue_delayed_work+0x1d2/0x200
Code: 41 5e 41 5f e9 7f ee ff ff 90 0f 0b 90 e9 5d ff ff ff bf 02 00
00 00 e8 6c f3 07 00 89 c3 eb bd 90 0f 0b 90 e9 57 f> 0b 90 e9 65 fe
ff ff 90 0f 0b 90 e9 72 fe ff ff 90 0f 0b 90 e9
RSP: 0018:ffffc900014afad8 EFLAGS: 00010003
RAX: 0000000000000000 RBX: ffff888124d99988 RCX: ffffffff81399cc1
RDX: dffffc0000000000 RSI: ffff888114326e00 RDI: ffff888124d999f0
RBP: 000000000000ea60 R08: 0000000000000001 R09: ffffed10249b3331
R10: ffff888124d9998f R11: 0000000000000004 R12: 0000000000000040
R13: ffff888114326e00 R14: ffff888124d999d8 R15: ffff888114939020
FS:  0000000000000000(0000) GS:ffff88829f7fe000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe7a2b4038 CR3: 0000000120a6f000 CR4: 0000000000750ef0
PKRU: 55555554
Call Trace:
 <TASK>
 queue_delayed_work_on+0xb4/0xc0
 smb2_reconnect+0xb22/0xf50 [cifs]
 smb2_reconnect_server+0x413/0xd40 [cifs]
 ? __pfx_smb2_reconnect_server+0x10/0x10 [cifs]
 ? local_clock_noinstr+0xd/0xd0
 ? local_clock+0x15/0x30
 ? lock_release+0x29b/0x390
 process_one_work+0x4c5/0xa10
 ? __pfx_process_one_work+0x10/0x10
 ? __list_add_valid_or_report+0x37/0x120
 worker_thread+0x2f1/0x5a0
 ? __kthread_parkme+0xde/0x100
 ? __pfx_worker_thread+0x10/0x10
 kthread+0x1fe/0x380
 ? kthread+0x10f/0x380
 ? __pfx_kthread+0x10/0x10
 ? local_clock_noinstr+0xd/0xd0
 ? ret_from_fork+0x1b/0x1f0
 ? local_clock+0x15/0x30
 ? lock_release+0x29b/0x390
 ? rcu_is_watching+0x20/0x50
 ? __pfx_kthread+0x10/0x10
 ret_from_fork+0x15b/0x1f0
 ? __pfx_kthread+0x10/0x10
 ret_from_fork_asm+0x1a/0x30
 </TASK>
irq event stamp: 1116206
hardirqs last  enabled at (1116205): [<ffffffff8143af42>] __up_console_sem+0x52/0x60
hardirqs last disabled at (1116206): [<ffffffff81399f0e>] queue_delayed_work_on+0x6e/0xc0
softirqs last  enabled at (1116138): [<ffffffffc04562fd>] __smb_send_rqst+0x42d/0x950 [cifs]
softirqs last disabled at (1116136): [<ffffffff823d35e1>] release_sock+0x21/0xf0

Cc: linux-cifs@vger.kernel.org
Reported-by: David Howells <dhowells@redhat.com>
Fixes: 42ca547 ("cifs: do not disable interface polling on failure")
Reviewed-by: David Howells <dhowells@redhat.com>
Tested-by: David Howells <dhowells@redhat.com>
Reviewed-by: Shyam Prasad N <nspmangalore@gmail.com>
Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

…terface

collect_md property on xfrm interfaces can only be set on device creation,
thus xfrmi_changelink() should fail when called on such interfaces.

The check to enforce this was done only in the case where the xi was
returned from xfrmi_locate() which doesn't look for the collect_md
interface, and thus the validation was never reached.

Calling changelink would thus errornously place the special interface xi
in the xfrmi_net->xfrmi hash, but since it also exists in the
xfrmi_net->collect_md_xfrmi pointer it would lead to a double free when
the net namespace was taken down [1].

Change the check to use the xi from netdev_priv which is available earlier
in the function to prevent changes in xfrm collect_md interfaces.

[1] resulting oops:
[    8.516540] kernel BUG at net/core/dev.c:12029!
[    8.516552] Oops: invalid opcode: 0000 [#1] SMP NOPTI
[    8.516559] CPU: 0 UID: 0 PID: 12 Comm: kworker/u80:0 Not tainted 6.15.0-virtme #5 PREEMPT(voluntary)
[    8.516565] Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[    8.516569] Workqueue: netns cleanup_net
[    8.516579] RIP: 0010:unregister_netdevice_many_notify+0x101/0xab0
[    8.516590] Code: 90 0f 0b 90 48 8b b0 78 01 00 00 48 8b 90 80 01 00 00 48 89 56 08 48 89 32 4c 89 80 78 01 00 00 48 89 b8 80 01 00 00 eb ac 90 <0f> 0b 48 8b 45 00 4c 8d a0 88 fe ff ff 48 39 c5 74 5c 41 80 bc 24
[    8.516593] RSP: 0018:ffffa93b8006bd30 EFLAGS: 00010206
[    8.516598] RAX: ffff98fe4226e000 RBX: ffffa93b8006bd58 RCX: ffffa93b8006bc60
[    8.516601] RDX: 0000000000000004 RSI: 0000000000000000 RDI: dead000000000122
[    8.516603] RBP: ffffa93b8006bdd8 R08: dead000000000100 R09: ffff98fe4133c100
[    8.516605] R10: 0000000000000000 R11: 00000000000003d2 R12: ffffa93b8006be00
[    8.516608] R13: ffffffff96c1a510 R14: ffffffff96c1a510 R15: ffffa93b8006be00
[    8.516615] FS:  0000000000000000(0000) GS:ffff98fee73b7000(0000) knlGS:0000000000000000
[    8.516619] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    8.516622] CR2: 00007fcd2abd0700 CR3: 000000003aa40000 CR4: 0000000000752ef0
[    8.516625] PKRU: 55555554
[    8.516627] Call Trace:
[    8.516632]  <TASK>
[    8.516635]  ? rtnl_is_locked+0x15/0x20
[    8.516641]  ? unregister_netdevice_queue+0x29/0xf0
[    8.516650]  ops_undo_list+0x1f2/0x220
[    8.516659]  cleanup_net+0x1ad/0x2e0
[    8.516664]  process_one_work+0x160/0x380
[    8.516673]  worker_thread+0x2aa/0x3c0
[    8.516679]  ? __pfx_worker_thread+0x10/0x10
[    8.516686]  kthread+0xfb/0x200
[    8.516690]  ? __pfx_kthread+0x10/0x10
[    8.516693]  ? __pfx_kthread+0x10/0x10
[    8.516697]  ret_from_fork+0x82/0xf0
[    8.516705]  ? __pfx_kthread+0x10/0x10
[    8.516709]  ret_from_fork_asm+0x1a/0x30
[    8.516718]  </TASK>

Fixes: abc340b ("xfrm: interface: support collect metadata mode")
Reported-by: Lonial Con <kongln9170@gmail.com>
Signed-off-by: Eyal Birger <eyal.birger@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

pert script tests fails with segmentation fault as below:

  92: perf script tests:
  --- start ---
  test child forked, pid 103769
  DB test
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.012 MB /tmp/perf-test-script.7rbftEpOzX/perf.data (9 samples) ]
  /usr/libexec/perf-core/tests/shell/script.sh: line 35:
  103780 Segmentation fault      (core dumped)
  perf script -i "${perfdatafile}" -s "${db_test}"
  --- Cleaning up ---
  ---- end(-1) ----
  92: perf script tests                                               : FAILED!

Backtrace pointed to :
	#0  0x0000000010247dd0 in maps.machine ()
	#1  0x00000000101d178c in db_export.sample ()
	#2  0x00000000103412c8 in python_process_event ()
	#3  0x000000001004eb28 in process_sample_event ()
	#4  0x000000001024fcd0 in machines.deliver_event ()
	#5  0x000000001025005c in perf_session.deliver_event ()
	#6  0x00000000102568b0 in __ordered_events__flush.part.0 ()
	#7  0x0000000010251618 in perf_session.process_events ()
	#8  0x0000000010053620 in cmd_script ()
	#9  0x00000000100b5a28 in run_builtin ()
	#10 0x00000000100b5f94 in handle_internal_command ()
	#11 0x0000000010011114 in main ()

Further investigation reveals that this occurs in the `perf script tests`,
because it uses `db_test.py` script. This script sets `perf_db_export_mode = True`.

With `perf_db_export_mode` enabled, if a sample originates from a hypervisor,
perf doesn't set maps for "[H]" sample in the code. Consequently, `al->maps` remains NULL
when `maps__machine(al->maps)` is called from `db_export__sample`.

As al->maps can be NULL in case of Hypervisor samples , use thread->maps
because even for Hypervisor sample, machine should exist.
If we don't have machine for some reason, return -1 to avoid segmentation fault.

Reported-by: Disha Goel <disgoel@linux.ibm.com>
Signed-off-by: Aditya Bodkhe <aditya.b1@linux.ibm.com>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Disha Goel <disgoel@linux.ibm.com>
Link: https://lore.kernel.org/r/20250429065132.36839-1-adityab1@linux.ibm.com
Suggested-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Without the change `perf `hangs up on charaster devices. On my system
it's enough to run system-wide sampler for a few seconds to get the
hangup:

    $ perf record -a -g --call-graph=dwarf
    $ perf report
    # hung

`strace` shows that hangup happens on reading on a character device
`/dev/dri/renderD128`

    $ strace -y -f -p 2780484
    strace: Process 2780484 attached
    pread64(101</dev/dri/renderD128>, strace: Process 2780484 detached

It's call trace descends into `elfutils`:

    $ gdb -p 2780484
    (gdb) bt
    #0  0x00007f5e508f04b7 in __libc_pread64 (fd=101, buf=0x7fff9df7edb0, count=0, offset=0)
        at ../sysdeps/unix/sysv/linux/pread64.c:25
    #1  0x00007f5e52b79515 in read_file () from /<<NIX>>/elfutils-0.192/lib/libelf.so.1
    #2  0x00007f5e52b25666 in libdw_open_elf () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
    #3  0x00007f5e52b25907 in __libdw_open_file () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
    #4  0x00007f5e52b120a9 in dwfl_report_elf@@ELFUTILS_0.156 ()
       from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
    #5  0x000000000068bf20 in __report_module (al=al@entry=0x7fff9df80010, ip=ip@entry=139803237033216, ui=ui@entry=0x5369b5e0)
        at util/dso.h:537
    #6  0x000000000068c3d1 in report_module (ip=139803237033216, ui=0x5369b5e0) at util/unwind-libdw.c:114
    #7  frame_callback (state=0x535aef10, arg=0x5369b5e0) at util/unwind-libdw.c:242
    #8  0x00007f5e52b261d3 in dwfl_thread_getframes () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
    #9  0x00007f5e52b25bdb in get_one_thread_cb () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
    #10 0x00007f5e52b25faa in dwfl_getthreads () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
    #11 0x00007f5e52b26514 in dwfl_getthread_frames () from /<<NIX>>/elfutils-0.192/lib/libdw.so.1
    #12 0x000000000068c6ce in unwind__get_entries (cb=cb@entry=0x5d4620 <unwind_entry>, arg=arg@entry=0x10cd5fa0,
        thread=thread@entry=0x1076a290, data=data@entry=0x7fff9df80540, max_stack=max_stack@entry=127,
        best_effort=best_effort@entry=false) at util/thread.h:152
    #13 0x00000000005dae95 in thread__resolve_callchain_unwind (evsel=0x106006d0, thread=0x1076a290, cursor=0x10cd5fa0,
        sample=0x7fff9df80540, max_stack=127, symbols=true) at util/machine.c:2939
    #14 thread__resolve_callchain_unwind (thread=0x1076a290, cursor=0x10cd5fa0, evsel=0x106006d0, sample=0x7fff9df80540,
        max_stack=127, symbols=true) at util/machine.c:2920
    #15 __thread__resolve_callchain (thread=0x1076a290, cursor=0x10cd5fa0, evsel=0x106006d0, evsel@entry=0x7fff9df80440,
        sample=0x7fff9df80540, parent=parent@entry=0x7fff9df804a0, root_al=root_al@entry=0x7fff9df80440, max_stack=127, symbols=true)
        at util/machine.c:2970
    #16 0x00000000005d0cb2 in thread__resolve_callchain (thread=<optimized out>, cursor=<optimized out>, evsel=0x7fff9df80440,
        sample=<optimized out>, parent=0x7fff9df804a0, root_al=0x7fff9df80440, max_stack=127) at util/machine.h:198
    #17 sample__resolve_callchain (sample=<optimized out>, cursor=<optimized out>, parent=parent@entry=0x7fff9df804a0,
        evsel=evsel@entry=0x106006d0, al=al@entry=0x7fff9df80440, max_stack=max_stack@entry=127) at util/callchain.c:1127
    #18 0x0000000000617e08 in hist_entry_iter__add (iter=iter@entry=0x7fff9df80480, al=al@entry=0x7fff9df80440, max_stack_depth=127,
        arg=arg@entry=0x7fff9df81ae0) at util/hist.c:1255
    #19 0x000000000045d2d0 in process_sample_event (tool=0x7fff9df81ae0, event=<optimized out>, sample=0x7fff9df80540,
        evsel=0x106006d0, machine=<optimized out>) at builtin-report.c:334
    #20 0x00000000005e3bb1 in perf_session__deliver_event (session=0x105ff2c0, event=0x7f5c7d735ca0, tool=0x7fff9df81ae0,
        file_offset=2914716832, file_path=0x105ffbf0 "perf.data") at util/session.c:1367
    #21 0x00000000005e8d93 in do_flush (oe=0x105ffa50, show_progress=false) at util/ordered-events.c:245
    #22 __ordered_events__flush (oe=0x105ffa50, how=OE_FLUSH__ROUND, timestamp=<optimized out>) at util/ordered-events.c:324
    #23 0x00000000005e1f64 in perf_session__process_user_event (session=0x105ff2c0, event=0x7f5c7d752b18, file_offset=2914835224,
        file_path=0x105ffbf0 "perf.data") at util/session.c:1419
    #24 0x00000000005e47c7 in reader__read_event (rd=rd@entry=0x7fff9df81260, session=session@entry=0x105ff2c0,
    --Type <RET> for more, q to quit, c to continue without paging--
    quit
        prog=prog@entry=0x7fff9df81220) at util/session.c:2132
    #25 0x00000000005e4b37 in reader__process_events (rd=0x7fff9df81260, session=0x105ff2c0, prog=0x7fff9df81220)
        at util/session.c:2181
    #26 __perf_session__process_events (session=0x105ff2c0) at util/session.c:2226
    #27 perf_session__process_events (session=session@entry=0x105ff2c0) at util/session.c:2390
    #28 0x0000000000460add in __cmd_report (rep=0x7fff9df81ae0) at builtin-report.c:1076
    #29 cmd_report (argc=<optimized out>, argv=<optimized out>) at builtin-report.c:1827
    #30 0x00000000004c5a40 in run_builtin (p=p@entry=0xd8f7f8 <commands+312>, argc=argc@entry=1, argv=argv@entry=0x7fff9df844b0)
        at perf.c:351
    #31 0x00000000004c5d63 in handle_internal_command (argc=argc@entry=1, argv=argv@entry=0x7fff9df844b0) at perf.c:404
    #32 0x0000000000442de3 in run_argv (argcp=<synthetic pointer>, argv=<synthetic pointer>) at perf.c:448
    #33 main (argc=<optimized out>, argv=0x7fff9df844b0) at perf.c:556

The hangup happens because nothing in` perf` or `elfutils` checks if a
mapped file is easily readable.

The change conservatively skips all non-regular files.

Signed-off-by: Sergei Trofimovich <slyich@gmail.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20250505174419.2814857-1-slyich@gmail.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Symbolize stack traces by creating a live machine. Add this
functionality to dump_stack and switch dump_stack users to use
it. Switch TUI to use it. Add stack traces to the child test function
which can be useful to diagnose blocked code.

Example output:
```
$ perf test -vv PERF_RECORD_
...
  7: PERF_RECORD_* events & perf_sample fields:
  7: PERF_RECORD_* events & perf_sample fields                       : Running (1 active)
^C
Signal (2) while running tests.
Terminating tests with the same signal
Internal test harness failure. Completing any started tests:
:  7: PERF_RECORD_* events & perf_sample fields:

---- unexpected signal (2) ----
    #0 0x55788c6210a3 in child_test_sig_handler builtin-test.c:0
    #1 0x7fc12fe49df0 in __restore_rt libc_sigaction.c:0
    #2 0x7fc12fe99687 in __internal_syscall_cancel cancellation.c:64
    #3 0x7fc12fee5f7a in clock_nanosleep@GLIBC_2.2.5 clock_nanosleep.c:72
    #4 0x7fc12fef1393 in __nanosleep nanosleep.c:26
    #5 0x7fc12ff02d68 in __sleep sleep.c:55
    #6 0x55788c63196b in test__PERF_RECORD perf-record.c:0
    #7 0x55788c620fb0 in run_test_child builtin-test.c:0
    #8 0x55788c5bd18d in start_command run-command.c:127
    #9 0x55788c621ef3 in __cmd_test builtin-test.c:0
    #10 0x55788c6225bf in cmd_test ??:0
    #11 0x55788c5afbd0 in run_builtin perf.c:0
    #12 0x55788c5afeeb in handle_internal_command perf.c:0
    #13 0x55788c52b383 in main ??:0
    #14 0x7fc12fe33ca8 in __libc_start_call_main libc_start_call_main.h:74
    #15 0x7fc12fe33d65 in __libc_start_main@@GLIBC_2.34 libc-start.c:128
    #16 0x55788c52b9d1 in _start ??:0

---- unexpected signal (2) ----
    #0 0x55788c6210a3 in child_test_sig_handler builtin-test.c:0
    #1 0x7fc12fe49df0 in __restore_rt libc_sigaction.c:0
    #2 0x7fc12fea3a14 in pthread_sigmask@GLIBC_2.2.5 pthread_sigmask.c:45
    #3 0x7fc12fe49fd9 in __GI___sigprocmask sigprocmask.c:26
    #4 0x7fc12ff2601b in __longjmp_chk longjmp.c:36
    #5 0x55788c6210c0 in print_test_result.isra.0 builtin-test.c:0
    #6 0x7fc12fe49df0 in __restore_rt libc_sigaction.c:0
    #7 0x7fc12fe99687 in __internal_syscall_cancel cancellation.c:64
    #8 0x7fc12fee5f7a in clock_nanosleep@GLIBC_2.2.5 clock_nanosleep.c:72
    #9 0x7fc12fef1393 in __nanosleep nanosleep.c:26
    #10 0x7fc12ff02d68 in __sleep sleep.c:55
    #11 0x55788c63196b in test__PERF_RECORD perf-record.c:0
    #12 0x55788c620fb0 in run_test_child builtin-test.c:0
    #13 0x55788c5bd18d in start_command run-command.c:127
    #14 0x55788c621ef3 in __cmd_test builtin-test.c:0
    #15 0x55788c6225bf in cmd_test ??:0
    #16 0x55788c5afbd0 in run_builtin perf.c:0
    #17 0x55788c5afeeb in handle_internal_command perf.c:0
    #18 0x55788c52b383 in main ??:0
    #19 0x7fc12fe33ca8 in __libc_start_call_main libc_start_call_main.h:74
    #20 0x7fc12fe33d65 in __libc_start_main@@GLIBC_2.34 libc-start.c:128
    #21 0x55788c52b9d1 in _start ??:0
  7: PERF_RECORD_* events & perf_sample fields                       : Skip (permissions)
```

Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250624210500.2121303-1-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Calling perf top with branch filters enabled on Intel CPU's
with branch counters logging (A.K.A LBR event logging [1]) support
results in a segfault.

$ perf top  -e '{cpu_core/cpu-cycles/,cpu_core/event=0xc6,umask=0x3,frontend=0x11,name=frontend_retired_dsb_miss/}' -j any,counter
...
Thread 27 "perf" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffafff76c0 (LWP 949003)]
perf_env__find_br_cntr_info (env=0xf66dc0 <perf_env>, nr=0x0, width=0x7fffafff62c0) at util/env.c:653
653			*width = env->cpu_pmu_caps ? env->br_cntr_width :
(gdb) bt
 #0  perf_env__find_br_cntr_info (env=0xf66dc0 <perf_env>, nr=0x0, width=0x7fffafff62c0) at util/env.c:653
 #1  0x00000000005b1599 in symbol__account_br_cntr (branch=0x7fffcc3db580, evsel=0xfea2d0, offset=12, br_cntr=8) at util/annotate.c:345
 #2  0x00000000005b17fb in symbol__account_cycles (addr=5658172, start=5658160, sym=0x7fffcc0ee420, cycles=539, evsel=0xfea2d0, br_cntr=8) at util/annotate.c:389
 #3  0x00000000005b1976 in addr_map_symbol__account_cycles (ams=0x7fffcd7b01d0, start=0x7fffcd7b02b0, cycles=539, evsel=0xfea2d0, br_cntr=8) at util/annotate.c:422
 #4  0x000000000068d57f in hist__account_cycles (bs=0x110d288, al=0x7fffafff6540, sample=0x7fffafff6760, nonany_branch_mode=false, total_cycles=0x0, evsel=0xfea2d0) at util/hist.c:2850
 #5  0x0000000000446216 in hist_iter__top_callback (iter=0x7fffafff6590, al=0x7fffafff6540, single=true, arg=0x7fffffff9e00) at builtin-top.c:737
 #6  0x0000000000689787 in hist_entry_iter__add (iter=0x7fffafff6590, al=0x7fffafff6540, max_stack_depth=127, arg=0x7fffffff9e00) at util/hist.c:1359
 #7  0x0000000000446710 in perf_event__process_sample (tool=0x7fffffff9e00, event=0x110d250, evsel=0xfea2d0, sample=0x7fffafff6760, machine=0x108c968) at builtin-top.c:845
 #8  0x0000000000447735 in deliver_event (qe=0x7fffffffa120, qevent=0x10fc200) at builtin-top.c:1211
 #9  0x000000000064ccae in do_flush (oe=0x7fffffffa120, show_progress=false) at util/ordered-events.c:245
 #10 0x000000000064d005 in __ordered_events__flush (oe=0x7fffffffa120, how=OE_FLUSH__TOP, timestamp=0) at util/ordered-events.c:324
 #11 0x000000000064d0ef in ordered_events__flush (oe=0x7fffffffa120, how=OE_FLUSH__TOP) at util/ordered-events.c:342
 #12 0x00000000004472a9 in process_thread (arg=0x7fffffff9e00) at builtin-top.c:1120
 #13 0x00007ffff6e7dba8 in start_thread (arg=<optimized out>) at pthread_create.c:448
 #14 0x00007ffff6f01b8c in __GI___clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:78

The cause is that perf_env__find_br_cntr_info tries to access a
null pointer pmu_caps in the perf_env struct. A similar issue exists
for homogeneous core systems which use the cpu_pmu_caps structure.

Fix this by populating cpu_pmu_caps and pmu_caps structures with
values from sysfs when calling perf top with branch stack sampling
enabled.

[1], LBR event logging introduced here:
https://lore.kernel.org/all/20231025201626.3000228-5-kan.liang@linux.intel.com/

Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Thomas Falcon <thomas.falcon@intel.com>
Link: https://lore.kernel.org/r/20250612163659.1357950-2-thomas.falcon@intel.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

profile allocation is wrongly setting the number of entries on the
rules vector before any ruleset is assigned. If profile allocation
fails between ruleset allocation and assigning the first ruleset,
free_ruleset() will be called with a null pointer resulting in an
oops.

[  107.350226] kernel BUG at mm/slub.c:545!
[  107.350912] Oops: invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
[  107.351447] CPU: 1 UID: 0 PID: 27 Comm: ksoftirqd/1 Not tainted 6.14.6-hwe-rlee287-dev+ #5
[  107.353279] Hardware name:[   107.350218] -QE-----------[ cutMU here ]--------- Ub---
[  107.3502untu26] kernel BUG a 24t mm/slub.c:545.!04 P
[  107.350912]C ( Oops: invalid oi4pcode: 0000 [#1]40 PREEMPT SMP NOPFXTI
 + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[  107.356054] RIP: 0010:__slab_free+0x152/0x340
[  107.356444] Code: 00 4c 89 ff e8 0f ac df 00 48 8b 14 24 48 8b 4c 24 20 48 89 44 24 08 48 8b 03 48 c1 e8 09 83 e0 01 88 44 24 13 e9 71 ff ff ff <0f> 0b 41 f7 44 24 08 87 04 00 00 75 b2 eb a8 41 f7 44 24 08 87 04
[  107.357856] RSP: 0018:ffffad4a800fbbb0 EFLAGS: 00010246
[  107.358937] RAX: ffff97ebc2a88e70 RBX: ffffd759400aa200 RCX: 0000000000800074
[  107.359976] RDX: ffff97ebc2a88e60 RSI: ffffd759400aa200 RDI: ffffad4a800fbc20
[  107.360600] RBP: ffffad4a800fbc50 R08: 0000000000000001 R09: ffffffff86f02cf2
[  107.361254] R10: 0000000000000000 R11: 0000000000000000 R12: ffff97ecc0049400
[  107.361934] R13: ffff97ebc2a88e60 R14: ffff97ecc0049400 R15: 0000000000000000
[  107.362597] FS:  0000000000000000(0000) GS:ffff97ecfb200000(0000) knlGS:0000000000000000
[  107.363332] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  107.363784] CR2: 000061c9545ac000 CR3: 0000000047aa6000 CR4: 0000000000750ef0
[  107.364331] PKRU: 55555554
[  107.364545] Call Trace:
[  107.364761]  <TASK>
[  107.364931]  ? local_clock+0x15/0x30
[  107.365219]  ? srso_alias_return_thunk+0x5/0xfbef5
[  107.365593]  ? kfree_sensitive+0x32/0x70
[  107.365900]  kfree+0x29d/0x3a0
[  107.366144]  ? srso_alias_return_thunk+0x5/0xfbef5
[  107.366510]  ? local_clock_noinstr+0xe/0xd0
[  107.366841]  ? srso_alias_return_thunk+0x5/0xfbef5
[  107.367209]  kfree_sensitive+0x32/0x70
[  107.367502]  aa_free_profile.part.0+0xa2/0x400
[  107.367850]  ? rcu_do_batch+0x1e6/0x5e0
[  107.368148]  aa_free_profile+0x23/0x60
[  107.368438]  label_free_switch+0x4c/0x80
[  107.368751]  label_free_rcu+0x1c/0x50
[  107.369038]  rcu_do_batch+0x1e8/0x5e0
[  107.369324]  ? rcu_do_batch+0x157/0x5e0
[  107.369626]  rcu_core+0x1b0/0x2f0
[  107.369888]  rcu_core_si+0xe/0x20
[  107.370156]  handle_softirqs+0x9b/0x3d0
[  107.370460]  ? smpboot_thread_fn+0x26/0x210
[  107.370790]  run_ksoftirqd+0x3a/0x70
[  107.371070]  smpboot_thread_fn+0xf9/0x210
[  107.371383]  ? __pfx_smpboot_thread_fn+0x10/0x10
[  107.371746]  kthread+0x10d/0x280
[  107.372010]  ? __pfx_kthread+0x10/0x10
[  107.372310]  ret_from_fork+0x44/0x70
[  107.372655]  ? __pfx_kthread+0x10/0x10
[  107.372974]  ret_from_fork_asm+0x1a/0x30
[  107.373316]  </TASK>
[  107.373505] Modules linked in: af_packet_diag mptcp_diag tcp_diag udp_diag raw_diag inet_diag snd_seq_dummy snd_hrtimer snd_seq_midi snd_seq_midi_event snd_rawmidi snd_seq snd_seq_device snd_timer snd soundcore qrtr binfmt_misc intel_rapl_msr intel_rapl_common kvm_amd ccp kvm irqbypass polyval_clmulni polyval_generic ghash_clmulni_intel sha256_ssse3 sha1_ssse3 aesni_intel crypto_simd cryptd i2c_piix4 i2c_smbus input_leds joydev sch_fq_codel msr parport_pc ppdev lp parport efi_pstore nfnetlink vsock_loopback vmw_vsock_virtio_transport_common vmw_vsock_vmci_transport vsock vmw_vmci dmi_sysfs qemu_fw_cfg ip_tables x_tables autofs4 hid_generic usbhid hid psmouse serio_raw floppy bochs pata_acpi
[  107.379086] ---[ end trace 0000000000000000 ]---

Don't set the count until a ruleset is actually allocated and
guard against free_ruleset() being called with a null pointer.

Reported-by: Ryan Lee <ryan.lee@canonical.com>
Fixes: 217af7e ("apparmor: refactor profile rules and attachments")
Signed-off-by: John Johansen <john.johansen@canonical.com>