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From: Richard Purdie <richard.purdie@linuxfoundation.org>
To: qemu-devel <qemu-devel@nongnu.org>
Subject: Re: VMs hanging with rcu stall problems
Date: Tue, 29 Jun 2021 14:34:46 +0100	[thread overview]
Message-ID: <709a88a0f24ed8fd5399a2be88fb9d57ceb0a25a.camel@linuxfoundation.org> (raw)
In-Reply-To: <89f4220fd2b973ebfed4bf4be0afbdefc44a9d4d.camel@linuxfoundation.org>

On Thu, 2021-06-03 at 11:02 +0100, Richard Purdie wrote:
> We're seeing intermittent rcu stalls in qemu system mode emulation which is 
> causing CI issues for us (Yocto Project). We're struggling to understand
> the cause and have tried several things to mitigate without much success. 
> The stalls are odd in that the log messages look incomplete. An example
> from last night:

To answer my own question, the issue is a kernel bug in RCU stall handling.
The fix:

https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git/commit/?h=rcu/next&id=c583bcb8f5ed

and patch which introduced the problem:

https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git/commit/?h=rcu/next&id=c583bcb8f5ed

Cheers,

Richard



      reply	other threads:[~2021-06-29 13:38 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-03 10:02 VMs hanging with rcu stall problems Richard Purdie
2021-06-29 13:34 ` Richard Purdie [this message]

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