linux-kernel - Re: [REGRESSION] lxc-stop hang on 5.17.x kernels

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Message-ID: <6ad38ecc-b2a9-f0e9-f7c7-f312a2763f97@kernel.dk>
Date:   Mon, 2 May 2022 07:26:00 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Daniel Harding <dharding@...ing180.net>,
        Pavel Begunkov <asml.silence@...il.com>
Cc:     regressions@...ts.linux.dev, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [REGRESSION] lxc-stop hang on 5.17.x kernels

On 5/2/22 7:17 AM, Daniel Harding wrote:
> I use lxc-4.0.12 on Gentoo, built with io-uring support
> (--enable-liburing), targeting liburing-2.1.  My kernel config is a
> very lightly modified version of Fedora's generic kernel config. After
> moving from the 5.16.x series to the 5.17.x kernel series, I started
> noticed frequent hangs in lxc-stop.  It doesn't happen 100% of the
> time, but definitely more than 50% of the time.  Bisecting narrowed
> down the issue to commit aa43477b040251f451db0d844073ac00a8ab66ee:
> io_uring: poll rework. Testing indicates the problem is still present
> in 5.18-rc5. Unfortunately I do not have the expertise with the
> codebases of either lxc or io-uring to try to debug the problem
> further on my own, but I can easily apply patches to any of the
> involved components (lxc, liburing, kernel) and rebuild for testing or
> validation.  I am also happy to provide any further information that
> would be helpful with reproducing or debugging the problem.

Do you have a recipe to reproduce the hang? That would make it
significantly easier to figure out.

-- 
Jens Axboe