Date: Wed, 20 Dec 2017 15:24:09 -0800
From: Tejun Heo <tj@kernel.org>
To: Dan Aloni <dan@kernelim.com>
Cc: Linux Kernel List <linux-kernel@vger.kernel.org>,
        cgroups@vger.kernel.org
Subject: Re: cgroups-related hard lockup in 4.14?
Message-ID: <20171220232409.GA1084507@devbig577.frc2.facebook.com>
References: <20171220225923.GA10374@gmail.com>
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On Thu, Dec 21, 2017 at 12:59:23AM +0200, Dan Aloni wrote:
> Hi,
> 
> Using netconsole, I was able to capture a hard lockup that seems to be
> related to cgroups, on a Fedora kernel based on v4.14.4.
> 
> By my analysis, from the 16 CPUs below, 14 are on css_set_lock, one is
> inside css_task_iter_advance, and the last one stuck trying to send an
> IPI, I guess because all other CPUs are spinning.
> 
> To add some context, I have been experiencing deadlocks on various
> machines starting from 4.13 and it's the first time I was able to
> capture one. It takes a few days to reproduce while idling or doing
> random work, and I have not yet come up with precise steps that can
> nail it.
> 
> I can try out patches in order to get more info on this issue.

Can you please try the following patch?

 https://marc.info/?l=linux-cgroups&m=151378281708793&q=raw

Thanks.

-- 
tejun