linux-kernel - Re: Q. drm/i915 shrinker, synchronize_rcu

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1494414097.6362.21.camel@linux.intel.com>
Date:   Wed, 10 May 2017 14:01:37 +0300
From:   Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>
To:     Andrea Arcangeli <aarcange@...hat.com>,
        Hugh Dickins <hughd@...gle.com>
Cc:     "J. R. Okajima" <hooanon05g@...il.com>, chris@...is-wilson.co.uk,
        daniel.vetter@...ll.ch, jani.nikula@...el.com,
        linux-kernel@...r.kernel.org
Subject: Re: Q. drm/i915 shrinker, synchronize_rcu_expedited() from handlers

On ke, 2017-05-10 at 12:43 +0200, Andrea Arcangeli wrote:
> It works for me too. I'm running my workstation also with
> synchronize_rcu removed from i915_gem_shrink_all in addition to the
> above. Isn't the oom method invoked from reclaim context too? As far
> as I can tell synchronize_rcu can end up throttling on a background
> synchronize_rcu_expedited(), so it might end up in the same issue
> unless removed too.

Thanks for testing and spotting my bad grepping, I'll add your T-b and
s
end v3.

Regards, Joonas

> Tested-by: Andrea Arcangeli <aarcange@...hat.com>
> 
> (I can't reproduce the lockups 100% of the time, but they never
> happened again with this patch and I happened to run the load that
> reproduces them a couple of times already with v4.11 and this patch
> applied)
> 
> It's also certainly improving performance by removing the
> synchronize_rcu_expedited from the _count methods where it was useless
> (in addition to unsafe).
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation