From: Tejun Heo <tj@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>,
Ingo Molnar <mingo@redhat.com>,
Sasha Levin <sasha.levin@oracle.com>,
Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
cgroups <cgroups@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Vladimir Davydov <vdavydov@parallels.com>,
kernel-team <kernel-team@fb.com>,
Dmitry Vyukov <dvyukov@google.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v4.4-rc7] sched: move sched lock synchronized bitfields in task_struct into ->atomic_flags
Date: Wed, 6 Jan 2016 08:44:53 -0500 [thread overview]
Message-ID: <20160106134453.GB29797@mtj.duckdns.org> (raw)
In-Reply-To: <20160101025628.GA3660@htj.duckdns.org>
On Thu, Dec 31, 2015 at 09:56:28PM -0500, Tejun Heo wrote:
> task_struct has a cluster of unsigned bitfields. Some are updated
> under scheduler locks while others are updated only by the task
> itself. Currently, the two classes of bitfields aren't distinguished
> and end up on the same word which can lead to clobbering when there
> are simultaneous read-modify-write attempts. While difficult to prove
> definitely, it's likely that the resulting inconsistency led to low
> frqeuency failures such as wrong memcg_may_oom state or loadavg
> underflow due to clobbered sched_contributes_to_load.
Ping.
--
tejun
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prev parent reply other threads:[~2016-01-06 13:44 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-13 18:59 [PATCH 1/2] memcg: flatten task_struct->memcg_oom Tejun Heo
2015-09-13 19:00 ` [PATCH v3 2/2] memcg: punt high overage reclaim to return-to-userland path Tejun Heo
2015-09-15 7:47 ` Johannes Weiner
2015-09-15 15:53 ` Tejun Heo
2015-09-15 16:12 ` Johannes Weiner
2015-09-15 16:22 ` Tejun Heo
2015-09-15 16:33 ` Johannes Weiner
2015-09-15 7:37 ` [PATCH 1/2] memcg: flatten task_struct->memcg_oom Johannes Weiner
2015-09-20 14:45 ` Sasha Levin
2015-09-21 20:01 ` Tejun Heo
2015-09-30 18:54 ` Tejun Heo
2015-11-25 14:43 ` Peter Zijlstra
2015-11-25 15:02 ` Peter Zijlstra
2015-11-25 15:31 ` Andrey Ryabinin
2015-11-25 17:34 ` Dmitry Vyukov
2015-11-25 17:44 ` Peter Zijlstra
2015-12-11 16:25 ` Tejun Heo
2015-12-15 19:22 ` Peter Zijlstra
2015-12-30 9:23 ` [PATCH v4.4-rc7] sched: isolate task_struct bitfields according to synchronization domains Tejun Heo
2015-12-30 20:10 ` Linus Torvalds
2015-12-30 20:17 ` Linus Torvalds
2015-12-30 20:41 ` Tejun Heo
2015-12-30 20:43 ` Linus Torvalds
2016-01-01 2:56 ` [PATCH v4.4-rc7] sched: move sched lock synchronized bitfields in task_struct into ->atomic_flags Tejun Heo
2016-01-06 13:44 ` Tejun Heo [this message]
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