Re: Regression in i915 for 4.11-rc1 - bisected to commit 69df05e11ab8

From: Chris Wilson
Date: Thu Mar 23 2017 - 16:45:41 EST


On Thu, Mar 23, 2017 at 01:19:43PM -0500, Larry Finger wrote:
> Since kernel 4.11-rc1, my desktop (Plasma5/KDE) has encountered
> intermittent hangs with the following information in the logs:
>
> linux-4v1g.suse kernel: [drm] GPU HANG: ecode 7:0:0xf3cffffe, in
> plasmashell [1283], reason: Hang on render ring, action: reset
> linux-4v1g.suse kernel: [drm] GPU hangs can indicate a bug anywhere
> in the entire gfx stack, including userspace.
> linux-4v1g.suse kernel: [drm] Please file a _new_ bug report on
> bugs.freedesktop.org against DRI -> DRM/Intel
> linux-4v1g.suse kernel: [drm] drm/i915 developers can then reassign
> to the right component if it's not a kernel issue.
> linux-4v1g.suse kernel: [drm] The gpu crash dump is required to
> analyze gpu hangs, so please always attach it.
> linux-4v1g.suse kernel: [drm] GPU crash dump saved to /sys/class/drm/card0/error
> linux-4v1g.suse kernel: drm/i915: Resetting chip after gpu hang
>
> This problem was added to
> https://bugs.freedesktop.org/show_bug.cgi?id=99380, but it probably
> is a different bug, as the OP in that report has problems with
> kernel 4.10.x, whereas my problem did not appear until 4.11.

Close. Actually that patch touches code you are not using (oa-perf and
gvt), the real culprit was e8a9c58fcd9a ("drm/i915: Unify active context
tracking between legacy/execlists/guc").

The fix

commit 5d4bac5503fcc67dd7999571e243cee49371aef7
Author: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Date: Wed Mar 22 20:59:30 2017 +0000

drm/i915: Restore marking context objects as dirty on pinning

Commit e8a9c58fcd9a ("drm/i915: Unify active context tracking between
legacy/execlists/guc") converted the legacy intel_ringbuffer submission
to the same context pinning mechanism as execlists - that is to pin the
context until the subsequent request is retired. Previously it used the
vma retirement of the context object to keep itself pinned until the
next request (after i915_vma_move_to_active()). In the conversion, I
missed that the vma retirement was also responsible for marking the
object as dirty. Mark the context object as dirty when pinning
(equivalent to execlists) which ensures that if the context is swapped
out due to mempressure or suspend/hibernation, when it is loaded back in
it does so with the previous state (and not all zero).

Fixes: e8a9c58fcd9a ("drm/i915: Unify active context tracking between legacy/execlists/guc")
Reported-by: Dennis Gilmore <dennis@xxxxxxxx>
Reported-by: Mathieu Marquer <mathieu.marquer@xxxxxxxxx>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99993
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100181
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Cc: <drm-intel-fixes@xxxxxxxxxxxxxxxxxxxxx> # v4.11-rc1
Link: http://patchwork.freedesktop.org/patch/msgid/20170322205930.12762-1-chris@xxxxxxxxxxxxxxxxxx
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>

went in this morning and so will be upstreamed ~next week.
-Chris

--
Chris Wilson, Intel Open Source Technology Centre