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<body><span class="vcard"><a class="email" href="mailto:chris@chris-wilson.co.uk" title="Chris Wilson <chris@chris-wilson.co.uk>"> <span class="fn">Chris Wilson</span></a>
</span> changed
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [SKL,GLK]gem_persistent_relocs@forked-interruptible-thrashing hangs"
href="https://bugs.freedesktop.org/show_bug.cgi?id=110618">bug 110618</a>
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<th>What</th>
<th>Removed</th>
<th>Added</th>
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<td style="text-align:right;">Resolution</td>
<td>---
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<td>FIXED
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<td style="text-align:right;">Status</td>
<td>NEW
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<td>RESOLVED
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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [SKL,GLK]gem_persistent_relocs@forked-interruptible-thrashing hangs"
href="https://bugs.freedesktop.org/show_bug.cgi?id=110618#c2">Comment # 2</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [SKL,GLK]gem_persistent_relocs@forked-interruptible-thrashing hangs"
href="https://bugs.freedesktop.org/show_bug.cgi?id=110618">bug 110618</a>
from <span class="vcard"><a class="email" href="mailto:chris@chris-wilson.co.uk" title="Chris Wilson <chris@chris-wilson.co.uk>"> <span class="fn">Chris Wilson</span></a>
</span></b>
<pre>My guess for the symptom here is the uninterruptible wait for flush_work in
i915_drop_caches_set(DROP_IDLE). Exactly why it wasn't able to idle, unknown as
we have no debug logs. However, I've been poking at the same code to avoid the
uninterruptible lockup, and so present
commit 3970564940ba0322bcefce7fd8fd35c2b85846bf
Author: Chris Wilson <<a href="mailto:chris@chris-wilson.co.uk">chris@chris-wilson.co.uk</a>>
Date: Tue May 7 13:11:08 2019 +0100
drm/i915: Stop spinning for DROP_IDLE (debugfs/i915_drop_caches)
If the user is racing a call to debugfs/i915_drop_caches with ongoing
submission from another thread/process, we may never end up idling the
GPU and be uninterruptibly spinning in debugfs/i915_drop_caches trying
to catch an idle moment.
Just flush the work once, that should be enough to park the system under
correct conditions. Outside of those we either have a driver bug or the
user is racing themselves. Sadly, because the user may be provoking the
unwanted situation we can't put a warn here to attract attention to a
probable bug.
Signed-off-by: Chris Wilson <<a href="mailto:chris@chris-wilson.co.uk">chris@chris-wilson.co.uk</a>>
Reviewed-by: Tvrtko Ursulin <<a href="mailto:tvrtko.ursulin@intel.com">tvrtko.ursulin@intel.com</a>>
Link:
<a href="https://patchwork.freedesktop.org/patch/msgid/20190507121108.18377-4-chris@chris-wilson.co.uk">https://patchwork.freedesktop.org/patch/msgid/20190507121108.18377-4-chris@chris-wilson.co.uk</a></pre>
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