Re: [PATCH] scsi: core: run queue in case of IO queueing failure

Ming Lei
2020-07-14T00:37:27Z

On Wed, Jul 08, 2020 at 09:14:05PM +0800, Ming Lei wrote:
> IO requests may be held in scheduler queue because of resource contention.
> However, not like normal completion, when queueing request failed, we don't
> ask block layer to queue these requests, so IO hang[1] is caused.
>
> Fix this issue by run queue when IO request failure happens.
>
> [1] IO hang log by running heavy IO with removing scsi device
>
> [ 39.054963] scsi 13:0:0:0: rejecting I/O to dead device
> [ 39.058700] scsi 13:0:0:0: rejecting I/O to dead device
> [ 39.087855] sd 13:0:0:1: [sdd] Synchronizing SCSI cache
> [ 39.088909] scsi 13:0:0:1: rejecting I/O to dead device
> [ 39.095351] scsi 13:0:0:1: rejecting I/O to dead device
> [ 39.096962] scsi 13:0:0:1: rejecting I/O to dead device
> [ 247.021859] INFO: task scsi-stress-rem:813 blocked for more than 122 seconds.
> [ 247.023258] Not tainted 5.8.0-rc2 #8
> [ 247.024069] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ 247.025331] scsi-stress-rem D 0 813 802 0x00004000
> [ 247.025334] Call Trace:
> [ 247.025354] __schedule+0x504/0x55f
> [ 247.027987] schedule+0x72/0xa8
> [ 247.027991] blk_mq_freeze_queue_wait+0x63/0x8c
> [ 247.027994] ? do_wait_intr_irq+0x7a/0x7a
> [ 247.027996] blk_cleanup_queue+0x4b/0xc9
> [ 247.028000] __scsi_remove_device+0xf6/0x14e
> [ 247.028002] scsi_remove_device+0x21/0x2b
> [ 247.029037] sdev_store_delete+0x58/0x7c
> [ 247.029041] kernfs_fop_write+0x10d/0x14f
> [ 247.031281] vfs_write+0xa2/0xdf
> [ 247.032670] ksys_write+0x6b/0xb3
> [ 247.032673] do_syscall_64+0x56/0x82
> [ 247.034053] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [ 247.034059] RIP: 0033:0x7f69f39e9008
> [ 247.036330] Code: Bad RIP value.
> [ 247.036331] RSP: 002b:00007ffdd8116498 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> [ 247.037613] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f69f39e9008
> [ 247.039714] RDX: 0000000000000002 RSI: 000055cde92a0ab0 RDI: 0000000000000001
> [ 247.039715] RBP: 000055cde92a0ab0 R08: 000000000000000a R09: 00007f69f3a79e80
> [ 247.039716] R10: 000000000000000a R11: 0000000000000246 R12: 00007f69f3abb780
> [ 247.039717] R13: 0000000000000002 R14: 00007f69f3ab6740 R15: 0000000000000002
>
> Cc: linux-block@vger.kernel.org
> Cc: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
> drivers/scsi/scsi_lib.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index 534b85e87c80..4d7fab9e8af9 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -1694,6 +1694,16 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
> */
> if (req->rq_flags & RQF_DONTPREP)
> scsi_mq_uninit_cmd(cmd);
> +
> + /*
> + * Requests may be held in block layer queue because of
> + * resource contention. We usually run queue in normal
> + * completion for queuing these requests again. Block layer
> + * will finish this failed request simply, run queue in case
> + * of IO queueing failure so that requests can get chance to
> + * be finished.
> + */
> + scsi_run_queue(q);
> break;
> }
> return ret;

Hello Guys,

Ping...

Thanks,
Ming