From: Thomas Gleixner <tglx@linutronix.de>
To: Naresh Kamboju <naresh.kamboju@linaro.org>,
Jakub Kicinski <kuba@kernel.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>,
open list <linux-kernel@vger.kernel.org>,
linux-stable <stable@vger.kernel.org>,
rcu@vger.kernel.org,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
lkft-triage@lists.linaro.org, Netdev <netdev@vger.kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Sasha Levin <sashal@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Matthew Wilcox <willy@infradead.org>
Subject: Re: [stabe-rc 5.9 ] sched: core.c:7270 Illegal context switch in RCU-bh read-side critical section!
Date: Wed, 16 Dec 2020 16:21:12 +0100 [thread overview]
Message-ID: <87lfdxsro7.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <CA+G9fYt_zxDSN5Qkx=rBE_ZkjirOBQ3QpFRy-gkqbjbJ=n1Z4Q@mail.gmail.com>
On Wed, Dec 16 2020 at 15:55, Naresh Kamboju wrote:
> On Tue, 15 Dec 2020 at 23:52, Jakub Kicinski <kuba@kernel.org> wrote:
>> > Or you could place checks for being in a BH-disable further up in
>> > the code. Or build with CONFIG_DEBUG_INFO=y to allow more precise
>> > interpretation of this stack trace.
>
> I will try to reproduce this warning with DEBUG_INFO=y enabled kernel and
> get back to you with a better crash log.
>
>>
>> My money would be on the option that whatever run on this workqueue
>> before forgot to re-enable BH, but we already have a check for that...
>> Naresh, do you have the full log? Is there nothing like "BUG: workqueue
>> leaked lock" above the splat?
No, because it's in the middle of the work. The workqueue bug triggers
when the work has finished.
So cleanup_up() net does
....
synchronize_rcu(); <- might sleep. So up to here it should be fine.
list_for_each_entry_continue_reverse(ops, &pernet_list, list)
ops_exit_list(ops, &net_exit_list);
ops_exit_list() is called for each ops which then either invokes
ops->exit() or ops->exit_batch().
So one of those callbacks fails to reenable BH, so adding a check after
each invocation of ops->exit() and ops->exit_batch() for
!local_bh_disabled() should be able to identify the buggy callback.
Thanks,
tglx
prev parent reply other threads:[~2020-12-16 15:22 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-15 2:20 [stabe-rc 5.9 ] sched: core.c:7270 Illegal context switch in RCU-bh read-side critical section! Naresh Kamboju
2020-12-15 14:45 ` Paul E. McKenney
2020-12-15 18:22 ` Jakub Kicinski
2020-12-16 10:25 ` Naresh Kamboju
2020-12-16 15:21 ` Thomas Gleixner [this message]
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