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From: Marco Elver <elver@google.com>
To: Qian Cai <cai@lca.pw>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Will Deacon <will@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"paul E. McKenney" <paulmck@kernel.org>
Subject: Re: [PATCH] locking/osq_lock: fix a data race in osq_wait_next
Date: Tue, 28 Jan 2020 11:29:11 +0100	[thread overview]
Message-ID: <CANpmjNNFBLB4iB7gj3sR9y1RKB6PmneNZmfpyJ4418impvwqBA@mail.gmail.com> (raw)
In-Reply-To: <E65D0BFC-719A-4CF9-A934-55ACFF663F98@lca.pw>

On Tue, 28 Jan 2020 at 11:10, Qian Cai <cai@lca.pw> wrote:
>
>
>
> > On Jan 28, 2020, at 3:18 AM, Marco Elver <elver@google.com> wrote:
> >
> > This should be an instance of same-value-store, since the node->cpu is
> > per-CPU and smp_processor_id() should always be the same, at least
> > once it's published. I believe the data race I observed here before
> > KCSAN had KCSAN_REPORT_VALUE_CHANGE_ONLY on syzbot, and hasn't been
> > observed since. For the most part, that should deal with this case.
>
> Are you sure? I had KCSAN_REPORT_VALUE_CHANGE_ONLY=y here and saw something similar a splat. I’ll also double check on my side and provide the decoding.

The data race you reported in this thread is a different one (same
function, but different accesses). I will reply separately.

  reply	other threads:[~2020-01-28 10:29 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-22 16:38 [PATCH] locking/osq_lock: fix a data race in osq_wait_next Qian Cai
2020-01-22 16:59 ` Will Deacon
2020-01-22 17:08   ` Qian Cai
2020-01-22 22:38     ` Marco Elver
2020-01-22 23:54       ` Qian Cai
2020-01-23  9:39         ` Peter Zijlstra
2020-01-28  3:11           ` Qian Cai
2020-01-28 11:46             ` Marco Elver
2020-01-28 12:53               ` Qian Cai
2020-01-28 16:52               ` Peter Zijlstra
2020-01-28 16:56               ` Peter Zijlstra
2020-01-29  0:22                 ` Paul E. McKenney
2020-01-29 15:29                   ` Marco Elver
2020-01-29 18:40                     ` Peter Zijlstra
2020-01-30 13:39                       ` Marco Elver
2020-01-30 13:48                         ` Peter Zijlstra
2020-01-31  3:32                           ` Qian Cai
2020-01-29 18:49                   ` Peter Zijlstra
2020-01-29 19:26                     ` Paul E. McKenney
2020-01-23  9:36       ` Peter Zijlstra
2020-01-28  3:12         ` Qian Cai
2020-01-28  8:18           ` Marco Elver
2020-01-28 10:10             ` Qian Cai
2020-01-28 10:29               ` Marco Elver [this message]
2020-01-22 17:09 ` Peter Zijlstra

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