Bug 103096

Summary: [CI] igt@kms_addfb_basic@bad-pitch-0 - dmesg-warn - possible circular locking dependency detected
Product: DRI Reporter: Marta Löfstedt <marta.lofstedt>
Component: DRM/IntelAssignee: Intel GFX Bugs mailing list <intel-gfx-bugs>
Status: CLOSED DUPLICATE QA Contact: Intel GFX Bugs mailing list <intel-gfx-bugs>
Severity: normal    
Priority: medium CC: intel-gfx-bugs
Version: DRI git   
Hardware: Other   
OS: All   
Whiteboard: ReadyForDev
i915 platform: BXT, HSW, KBL, SNB i915 features: display/Other

Description Marta Löfstedt 2017-10-04 09:35:19 UTC
On CI_DRM_3167 all shards dmesg-warn on lockdep:	

[   56.872627] ======================================================
[   56.872629] WARNING: possible circular locking dependency detected
[   56.872632] 4.14.0-rc3-CI-CI_DRM_3167+ #1 Tainted: G     U         
[   56.872634] ------------------------------------------------------
[   56.872637] kms_addfb_basic/1462 is trying to acquire lock:
[   56.872639]  (&dev->struct_mutex){+.+.}, at: [<ffffffffa01cc7d1>] i915_mutex_lock_interruptible+0x51/0x130 [i915]
[   56.872680] 
               but task is already holding lock:
[   56.872682]  (&mm->mmap_sem){++++}, at: [<ffffffff8104adad>] __do_page_fault+0x10d/0x570
[   56.872687] 
               which lock already depends on the new lock.

[   56.872690] 
               the existing dependency chain (in reverse order) is:

Note, this is not reproduced on CI_DRM_3168 nor CI_DRM_3169

Full data:
https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3167/shard-snb6/igt@kms_addfb_basic@bad-pitch-0.html
https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3167/shard-hsw3/igt@kms_addfb_basic@bad-pitch-0.html
https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3167/shard-apl5/igt@kms_addfb_basic@bad-pitch-0.html
https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3167/shard-kbl6/igt@kms_addfb_basic@bad-pitch-0.html
Comment 2 Daniel Vetter 2017-10-06 07:07:41 UTC
Just to make things clear: This is for the lockdep splat going through i915_gem_set_wedged/stop_machine. Anything else is probably a different splat (even when the 2 locks that close the loop might be the same, unfortunately you can't go by the top few lines in a lockdep splat but need to look at the full circle).
Comment 3 Daniel Vetter 2017-10-06 07:12:51 UTC

*** This bug has been marked as a duplicate of bug 102886 ***

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