From: Andrew Morton <akpm@linux-foundation.org>
To: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org,
Johannes Weiner <hannes@cmpxchg.org>,
Suren Baghdasaryan <surenb@google.com>,
Jason Xing <kerneljasonxing@linux.alibaba.com>,
Caspar Zhang <caspar@linux.alibaba.com>
Subject: Re: [PATCH v3] psi: get poll_work to run when calling poll syscall next time
Date: Thu, 22 Aug 2019 15:21:07 -0700 [thread overview]
Message-ID: <20190822152107.adc0d4cd374fcc3eb8e148a9@linux-foundation.org> (raw)
In-Reply-To: <1566357985-97781-1-git-send-email-joseph.qi@linux.alibaba.com>
On Wed, 21 Aug 2019 11:26:25 +0800 Joseph Qi <joseph.qi@linux.alibaba.com> wrote:
> Only when calling the poll syscall the first time can user
> receive POLLPRI correctly. After that, user always fails to
> acquire the event signal.
>
> Reproduce case:
> 1. Get the monitor code in Documentation/accounting/psi.txt
> 2. Run it, and wait for the event triggered.
> 3. Kill and restart the process.
>
> The question is why we can end up with poll_scheduled = 1 but the work
> not running (which would reset it to 0). And the answer is because the
> scheduling side sees group->poll_kworker under RCU protection and then
> schedules it, but here we cancel the work and destroy the worker. The
> cancel needs to pair with resetting the poll_scheduled flag.
Should this be backported into -stable kernels?
next prev parent reply other threads:[~2019-08-22 22:21 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-21 3:26 Joseph Qi
2019-08-22 22:21 ` Andrew Morton [this message]
2019-08-22 23:11 ` Suren Baghdasaryan
2019-08-22 23:17 ` Andrew Morton
2019-08-22 23:21 ` Suren Baghdasaryan
2019-08-23 0:53 ` Joseph Qi
2019-08-24 20:51 ` Andrew Morton
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