Re: aio tests failing on newer Linux kernels

Hi,

On Tue, Jul 28, 2026 at 12:00 PM Alexander Lakhin <exclusion(at)gmail(dot)com> wrote:
>
> Hello Aleksander and Michael,
>
> 28.07.2026 05:24, Michael Paquier пишет:
>
> On Mon, Jul 27, 2026 at 04:36:24PM +0300, Aleksander Alekseev wrote:
>
> AI suggests the new behavior is caused by the "io_uring: use region api
> for SQ/CQ" change landed in the kernel version 6.14.
>
> No idea about the AI argument, but..
>
> Two cents: I'm on Ubuntu 24.04 with Linux 6.14.0-37-generic and
> liburing 2.5 and the tests pass fine for me.
>
> You are not alone. Various buildfarm members are also turning red
> with random failures across multiple tests because of this issue.
>
>
> I think, I've found the difference -- on Debian I'm seeing:
> user(at)debian:~$ ulimit -l
> 8192
> vs
> vagrant(at)ubuntu:~$ ulimit -l
> 2044616
>
> Thus, with "ulimit -l 8192" set on Ubuntu 24.04, I've got the aio failures there as well:
> Linux ubuntu 6.14.0-37-generic #37~24.04.1-Ubuntu SMP PREEMPT_DYNAMIC Thu Nov 20 10:25:38 UTC 2 x86_64 x86_64 x86_64 GNU/Linux
>
> $ meson test test_aio_* -j 30
> ...
> Ok: 101
> Expected Fail: 0
> Fail: 19
> Unexpected Pass: 0
>
> Also reproduced on Fedora, with:
> Linux localhost.localdomain 6.17.10-100.fc41.x86_64 #1 SMP PREEMPT_DYNAMIC Mon Dec 1 16:10:21 UTC 2025 x86_64 GNU/Linux
> $ ulimit -l
> 8192
> (default)

Out of interest, I let Sol do some investigations for this issue. The
conclusion it reached seems to align with that of the AI tool used by
Alexander. However, I lacked the expertise to fully review/confirm it.
Not sure whether it is acceptable to post a 'could-be-sloppy' report
here.

--
Regards,
Xuneng Zhou
HighGo Software Co., Ltd.