[Bug 103950] [CI] igt@* - dmesg-warn - WARNING: possible circular locking dependency detected

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=103950

--- Comment #1 from Marta Löfstedt <marta.lofstedt at intel.com> ---
https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3397/shard-hsw3/igt@kms_cursor_crc@cursor-256x256-suspend.html

[  282.801181] Suspending console(s) (use no_console_suspend to debug)
[  282.809347] sd 4:0:0:0: [sda] Synchronizing SCSI cache
[  282.809672] sd 4:0:0:0: [sda] Stopping disk

[  282.921866] ======================================================
[  282.921867] WARNING: possible circular locking dependency detected
[  282.921868] 4.15.0-rc1-CI-CI_DRM_3397+ #1 Tainted: G     U          
[  282.921869] ------------------------------------------------------
[  282.921870] watchdog/1/15 is trying to acquire lock:
[  282.921870]  (&cpuctx_mutex){+.+.}, at: [<ffffffff8116071c>]
perf_event_ctx_lock_nested+0xbc/0x1d0
[  282.921875] 
               but now in release context of a crosslock acquired at the
following:
[  282.921876]  ((completion)&self->parked){+.+.}, at: [<ffffffff8109d69d>]
kthread_park+0x3d/0x50
[  282.921879] 
               which lock already depends on the new lock.

[  282.921879] 
               the existing dependency chain (in reverse order) is:
[  282.921879] 
               -> #3 ((completion)&self->parked){+.+.}:
[  282.921883]        wait_for_common+0x54/0x210
[  282.921884]        kthread_park+0x3d/0x50
[  282.921917]        i915_gem_reset_prepare_engine+0x1d/0x90 [i915]
[  282.921940]        i915_gem_reset_prepare+0x2c/0x60 [i915]
[  282.921957]        i915_reset+0x66/0x230 [i915]
[  282.921974]        i915_reset_device+0x1cb/0x230 [i915]
[  282.921991]        i915_handle_error+0x2d3/0x430 [i915]
[  282.922011]        i915_wedged_set+0x79/0xc0 [i915]
[  282.922013]        simple_attr_write+0xab/0xc0
[  282.922016]        full_proxy_write+0x4b/0x70
[  282.922017]        __vfs_write+0x1e/0x130
[  282.922017]        vfs_write+0xc0/0x1b0
[  282.922018]        SyS_write+0x40/0xa0
[  282.922020]        entry_SYSCALL_64_fastpath+0x1c/0x89
[  282.922020] 
               -> #2 (&dev->struct_mutex){+.+.}:
[  282.922023]        __mutex_lock+0x81/0x9b0
[  282.922044]        i915_mutex_lock_interruptible+0x47/0x130 [i915]
[  282.922065]        i915_gem_fault+0x201/0x760 [i915]
[  282.922067]        __do_fault+0x15/0x70
[  282.922069]        __handle_mm_fault+0x7bf/0xda0
[  282.922071]        handle_mm_fault+0x14f/0x2f0
[  282.922072]        __do_page_fault+0x2d1/0x560
[  282.922073]        page_fault+0x22/0x30
[  282.922073] 
               -> #1 (&mm->mmap_sem){++++}:
[  282.922076]        __might_fault+0x63/0x90
[  282.922078]        _copy_to_user+0x1e/0x70
[  282.922079]        perf_read+0x1aa/0x290
[  282.922080]        __vfs_read+0x1e/0x120
[  282.922081]        vfs_read+0xa1/0x150
[  282.922082]        SyS_read+0x40/0xa0
[  282.922083]        entry_SYSCALL_64_fastpath+0x1c/0x89
[  282.922083] 
               -> #0 (&cpuctx_mutex){+.+.}:
[  282.922085]        perf_event_ctx_lock_nested+0xbc/0x1d0
[  282.922086] 
               other info that might help us debug this:

[  282.922086] Chain exists of:
                 &cpuctx_mutex --> &dev->struct_mutex -->
(completion)&self->parked

[  282.922088]  Possible unsafe locking scenario by crosslock:

[  282.922089]        CPU0                    CPU1
[  282.922089]        ----                    ----
[  282.922089]   lock(&dev->struct_mutex);
[  282.922090]   lock((completion)&self->parked);
[  282.922091]                                lock(&cpuctx_mutex);
[  282.922092]                               
unlock((completion)&self->parked);
[  282.922093] 
                *** DEADLOCK ***

[  282.922094] 1 lock held by watchdog/1/15:
[  282.922094]  #0:  (&x->wait){....}, at: [<ffffffff810c7b03>]
complete+0x13/0x50
[  282.922098] 
               stack backtrace:
[  282.922100] CPU: 1 PID: 15 Comm: watchdog/1 Tainted: G     U          
4.15.0-rc1-CI-CI_DRM_3397+ #1
[  282.922100] Hardware name: MSI MS-7924/Z97M-G43(MS-7924), BIOS V1.12
02/15/2016
[  282.922101] Call Trace:
[  282.922105]  dump_stack+0x5f/0x86
[  282.922108]  print_circular_bug+0x230/0x3b0
[  282.922110]  check_prev_add+0x439/0x7b0
[  282.922112]  ? HARDIRQ_verbose+0x10/0x10
[  282.922115]  ? lock_commit_crosslock+0x3e8/0x640
[  282.922116]  lock_commit_crosslock+0x3e8/0x640
[  282.922118]  ? __kthread_parkme+0x39/0x90
[  282.922120]  ? smpboot_thread_fn+0x184/0x270
[  282.922122]  complete+0x1f/0x50
[  282.922123]  ? __kthread_parkme+0x39/0x90
[  282.922124]  __kthread_parkme+0x63/0x90
[  282.922126]  ? smpboot_thread_fn+0x2c/0x270
[  282.922127]  smpboot_thread_fn+0xaa/0x270
[  282.922128]  kthread+0x139/0x170
[  282.922130]  ? sort_range+0x20/0x20
[  282.922131]  ? kthread_create_on_node+0x40/0x40
[  282.922133]  ret_from_fork+0x24/0x30

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