Re: Q. drm/i915 shrinker, synchronize_rcu_expedited() from handlers

From	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Newsgroups	linux.kernel
Subject	Re: Q. drm/i915 shrinker, synchronize_rcu_expedited() from handlers
Date	2017-05-05 11:50 +0200
Message-ID	<tDI26-8l5-11@gated-at.bofh.it> (permalink)
References	<tBQdr-85f-3@gated-at.bofh.it> <tBTEm-1xV-1@gated-at.bofh.it> <tC8WJ-2PH-5@gated-at.bofh.it>
Organization	Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo

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On ma, 2017-05-01 at 11:05 +0900, J. R. Okajima wrote:
> Thanx for the reply.
> 
> Andrea Arcangeli:
> > 
> > Yes I already reported this, my original fix was way more efficient
> > (and also safer considering the above) than what landed upstream. My
> > feedback was ignored though.
> > 
> > https://lists.freedesktop.org/archives/intel-gfx/2017-April/125414.html
> 
> I see.
> Actually on my test system for v4.11-rc8, kthreadd, kworker, kswapd and
> others all stopped working due to the synchronize_rcu_expedited call
> from i915_gem_shrinker_count. It is definitly a show stopper for me as
> an i915 user.

Filing a bug in freedesktop.org with all the details is the fastest way
of getting help. Without the bug (and with such little information as
the previous e-mail) it's hard to estimate the extent and nature of the
bug.

I've anyway gone and prepared a patch to drop the RCU sync completely
from shrinker phase, as discussed originally with Chris.

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation

Thread

Q. drm/i915 shrinker, synchronize_rcu_expedited() from handlers "J. R. Okajima" <hooanon05g@gmail.com> - 2017-04-30 08:10 +0200
  Re: Q. drm/i915 shrinker, synchronize_rcu_expedited() from handlers Andrea Arcangeli <aarcange@redhat.com> - 2017-04-30 11:50 +0200
    Re: Q. drm/i915 shrinker, synchronize_rcu_expedited() from handlers "J. R. Okajima" <hooanon05g@gmail.com> - 2017-05-01 04:10 +0200
      Re: Q. drm/i915 shrinker, synchronize_rcu_expedited() from handlers Joonas Lahtinen <joonas.lahtinen@linux.intel.com> - 2017-05-05 11:50 +0200
        Re: Q. drm/i915 shrinker, synchronize_rcu_expedited() from  handlers Hugh Dickins <hughd@google.com> - 2017-05-06 00:00 +0200
          Re: Q. drm/i915 shrinker, synchronize_rcu_expedited() from handlers Joonas Lahtinen <joonas.lahtinen@linux.intel.com> - 2017-05-08 10:10 +0200
            Re: Q. drm/i915 shrinker, synchronize_rcu_expedited() from  handlers Hugh Dickins <hughd@google.com> - 2017-05-10 05:10 +0200
              Re: Q. drm/i915 shrinker, synchronize_rcu_expedited() from handlers Joonas Lahtinen <joonas.lahtinen@linux.intel.com> - 2017-05-10 12:00 +0200
              Re: Q. drm/i915 shrinker, synchronize_rcu_expedited() from handlers Andrea Arcangeli <aarcange@redhat.com> - 2017-05-10 12:50 +0200
                Re: Q. drm/i915 shrinker, synchronize_rcu_expedited() from handlers Joonas Lahtinen <joonas.lahtinen@linux.intel.com> - 2017-05-10 13:10 +0200
        Re: Q. drm/i915 shrinker, synchronize_rcu_expedited() from handlers "J. R. Okajima" <hooanon05g@gmail.com> - 2017-05-06 01:30 +0200

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