Bug 104009

Also,
https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_7387/shards.html

Now also on KBL-shards:

https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3426/shard-kbl1/igt@gem_tiled_swapping@non-threaded.html

This run:
https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3434/shard-hsw3/igt@gem_tiled_swapping@non-threaded.html

seem to match this pstore:
https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_3445/shard-hsw3/pstore2-1512165009_Panic_1.log

Created attachment 136141 [details]
pstore pulled from shard-hsw4 when Ci_DRM_3506 was running

 Pstore collection appear to be broken see bug 103706 so to get more data on this I managed to pull this pstore log from shards-hsw4 manually when CI_DRM_3506 was running. 
I believe this pstore show igt@gem_tiled_swapping@non-threaded behaving badly.

Hmm, looking at __lock_page(), I'm reminded of this bug:

Commit 50816c48997a ("sched/wait: Standardize internal naming of
wait-queue entries") changed the behavior of add_wait_queue() from
inserting the wait entry at the head of the wait queue to the tail of
the wait queue. This is the relevant hunk:

-void add_wait_queue(wait_queue_head_t *q, wait_queue_entry_t *wait)
+void add_wait_queue(wait_queue_head_t *q, struct wait_queue_entry *wq_entry)
 {
        unsigned long flags;

-       wait->flags &= ~WQ_FLAG_EXCLUSIVE;
+       wq_entry->flags &= ~WQ_FLAG_EXCLUSIVE;
        spin_lock_irqsave(&q->lock, flags);
-       __add_wait_queue(q, wait);
+       __add_wait_queue_entry_tail(q, wq_entry);
        spin_unlock_irqrestore(&q->lock, flags);
 }
 EXPORT_SYMBOL(add_wait_queue);

Note the change from __add_wait_queue() to
__add_wait_queue_entry_tail(). I'm assuming this was a typo since the
commit message doesn't mention any functional changes. This patch
restores the old behavior.

tip-bot:

Commit-ID:  c6b9d9a33029014446bd9ed84c1688f6d3d4eab9
Gitweb:     https://git.kernel.org/tip/c6b9d9a33029014446bd9ed84c1688f6d3d4eab9
Author:     Omar Sandoval <osandov@fb.com>
AuthorDate: Tue, 5 Dec 2017 23:15:31 -0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 6 Dec 2017 19:30:34 +0100
   
   sched/wait: Fix add_wait_queue() behavioral change


Drat, which is already in drm-tip.

I will duplicate this on bug 104218, to get better overview of the impact

*** This bug has been marked as a duplicate of bug 104218 ***