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

From: Daniel Harding
Date: Mon May 02 2022 - 09:17:47 EST


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