From: Petr Mladek <pmladek@suse.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Martin Liu <liumartin@google.com>,
Oleg Nesterov <oleg@redhat.com>,
Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Tejun Heo <tj@kernel.org>,
minchan@google.com, davidchao@google.com, jenhaochen@google.com,
clang-built-linux@googlegroups.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] kthread: Prevent deadlock when kthread_mod_delayed_work() races with kthread_cancel_delayed_work_sync()
Date: Mon, 14 Jun 2021 09:10:12 +0200 [thread overview]
Message-ID: <YMcA1BL5RVRm25bu@alley> (raw)
In-Reply-To: <20210611134125.bdb08ba0d2b6b87dc60d446d@linux-foundation.org>
On Fri 2021-06-11 13:41:25, Andrew Morton wrote:
> On Fri, 11 Jun 2021 09:16:52 +0200 Petr Mladek <pmladek@suse.com> wrote:
>
> > On Thu 2021-06-10 14:30:30, Andrew Morton wrote:
> > > On Thu, 10 Jun 2021 15:30:50 +0200 Petr Mladek <pmladek@suse.com> wrote:
> > >
> > > > The system might hang with the following backtrace:
> > >
> > > Well that's not good.
> >
> > Fortunately, the API users normally synchronize these operations
> > another way. The race should never happen when the API is used
> > a reasonable way,
> > see https://lore.kernel.org/lkml/YKZLnTNOlUQ85F2s@alley/
> >
> > > > Fixes: 9a6b06c8d9a220860468a ("kthread: allow to modify delayed kthread work")
> > > > Reported-by: Martin Liu <liumartin@google.com>
> > > > Signed-off-by: Petr Mladek <pmladek@suse.com>
> > >
> > > Was a -stable backport considered?
> >
> > Good point! It would make sense to backport it. System hang is never
> > good.
> >
> > Could you please add Cc: stable@vger.kernel.org or should I resend the
> > patchset?
>
> I made that change to patches 1&2. I don't think patch 3 need be
> backported?
Sounds good to me. Thanks a lot for the update.
Best Regards,
Petr
next prev parent reply other threads:[~2021-06-14 7:10 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-10 13:30 [PATCH 0/3] kthread_worker: Fix race between kthread_mod_delayed_work() and kthread_cancel_delayed_work_sync() Petr Mladek
2021-06-10 13:30 ` [PATCH 1/3] kthread_worker: Split code for canceling the delayed work timer Petr Mladek
2021-06-10 13:30 ` [PATCH 2/3] kthread: Prevent deadlock when kthread_mod_delayed_work() races with kthread_cancel_delayed_work_sync() Petr Mladek
2021-06-10 21:30 ` Andrew Morton
2021-06-11 7:16 ` Petr Mladek
2021-06-11 20:41 ` Andrew Morton
2021-06-14 7:10 ` Petr Mladek [this message]
2021-06-10 13:30 ` [PATCH 3/3] kthread_worker: Fix return value " Petr Mladek
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