From: Peter Zijlstra <peterz@infradead.org>
To: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: Spurious lockdep splat in v4.15-rc9
Date: Mon, 22 Jan 2018 18:40:31 +0100 [thread overview]
Message-ID: <20180122174031.GG2228@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180122171018.GF1096857@devbig577.frc2.facebook.com>
On Mon, Jan 22, 2018 at 09:10:18AM -0800, Tejun Heo wrote:
> Hello, Peter, Ingo.
>
> I get the below lockdep warning if I try to write a config into cgroup
> cpu.max file. It's warning about A-A deadlock, but it's obviously
> spurious - the system doesn't lock up and the warning is about two
> get_online_cpus() calls nesting.
Looks real, just not instantly fatal. It would generate an actual
deadlock the moment there is a contending hotplug operation around
though.
I'll have a wee look.
next prev parent reply other threads:[~2018-01-22 17:40 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-22 17:10 Spurious lockdep splat in v4.15-rc9 Tejun Heo
2018-01-22 17:40 ` Peter Zijlstra [this message]
2018-01-22 21:53 ` Peter Zijlstra
2018-01-22 22:03 ` Tejun Heo
2018-01-24 10:38 ` [tip:sched/urgent] sched/core: Fix cpu.max vs. cpuhotplug deadlock tip-bot for Peter Zijlstra
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