On 5/2/22 7:36 AM, Daniel Harding wrote: > On 5/2/22 16:26, Jens Axboe wrote: >> 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. > > I can reproduce it with just the following: > > sudo lxc-create --n lxc-test --template download --bdev dir --dir /var/lib/lxc/lxc-test/rootfs -- -d ubuntu -r bionic -a amd64 > sudo lxc-start -n lxc-test > sudo lxc-stop -n lxc-test > > The lxc-stop command never exits and the container continues running. > If that isn't sufficient to reproduce, please let me know. Thanks, that's useful! I'm at a conference this week and hence have limited amount of time to debug, hopefully Pavel has time to take a look at this. -- Jens Axboe
