On 2022-08-23 03:37, Song Liu wrote:
Thomas, have you tried to bisect with the fio repro?
Yes, just finished:
d32d3d0b47f7e34560ae3c55ddfcf68694813501 is the first bad commit
commit d32d3d0b47f7e34560ae3c55ddfcf68694813501
Author: Christoph Hellwig
Date: Mon Jun 14 13:17:34 2021 +0200
nvme-multipath: set QUEUE_FLAG_NOWAIT
The nvme multipathing code just dispatches bios to one of the blk-mq
based paths and never blocks on its own, so set QUEUE_FLAG_NOWAIT
to support REQ_NOWAIT bios.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d32d3d0b47f7e34560ae3c55ddfcf68694813501
So another NOWAIT issue -- similar to the bad commit which is causing
the mdraid issue I already found
(https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0f9650bd838efe5c52f7e5f40c3204ad59f1964d).
Reverting the commit, i.e. deleting
blk_queue_flag_set(QUEUE_FLAG_NOWAIT, head->disk->queue);
fixes the problem for me. Well, sort of. Looks like this will disable
io_uring. fio reproducer fails with
$ fio reproducer.fio
filename0: (g=0): rw=randwrite, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=io_uring, iodepth=1
fio-3.30
Starting 1 thread
fio: io_u error on file /srv/machines/fio/filename0.0.0: Operation not supported: write offset=12648448, buflen=4096
fio: pid=1585, err=95/file:io_u.c:1846, func=io_u error, error=Operation not supported
My MariaDB reproducer also doesn't trigger the problem anymore, but
probably for the same reason -- it cannot use io_uring anymore.
--
Regards,
Thomas
