On Sat, 2018-03-10 at 22:56 +0200, Jaco Kroon wrote: > On 22/02/2018 18:46, Bart Van Assche wrote: > > On 02/22/18 02:58, Jaco Kroon wrote: > > > We've been seeing sporadic IO lockups on recent kernels. > > > > Are you using the legacy I/O stack or blk-mq? If you are not yet using > > blk-mq, can you switch to blk-mq + scsi-mq + dm-mq? If the lockup is > > reproducible with blk-mq, can you share the output of the following > > command: > > > > (cd /sys/kernel/debug/block && find . -type f -exec grep -aH . {} \;) > > Looks like the lockups are far more frequent with everything on mq. > Just to confirm: > > CONFIG_SCSI_MQ_DEFAULT=y > CONFIG_DM_MQ_DEFAULT=y > > > Please find attached the output from the requested. > > http://downloads.uls.co.za/lockup/lockup-20180310-223036/ contains > additional stuff, surrounding that. Thanks, that helps. In block_debug.txt I see that only for /dev/sdm a request got stuck: $ grep 'busy=[^0]' block_debug.txt ./sdm/hctx0/tags:busy=9 But I can't see in the output that has been shared which I/O scheduler has been configured nor which SCSI LLD is involved. Can you please also share that information, e.g. by providing the output of the following commands: cat /sys/block/sdm/queue/scheduler find /sys -name sdm # provides the PCI ID lspci Thanks, Bart.