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

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Message-ID: <7925e262-e0d4-6791-e43b-d37e9d693414@living180.net>
Date:   Mon, 2 May 2022 16:17:30 +0300
From:   Daniel Harding <dharding@...ing180.net>
To:     Jens Axboe <axboe@...nel.dk>,
        Pavel Begunkov <asml.silence@...il.com>
Cc:     regressions@...ts.linux.dev, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [REGRESSION] lxc-stop hang on 5.17.x kernels

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.

Regards,

Daniel Harding

#regzbot introduced: aa43477b040251f451db0d844073ac00a8ab66ee