From: Ming Lei <ming.lei@redhat.com>

Date: Mon, 20 Jul 2020 10:54:35 +0800

Subject: scsi: core: Run queue in case of I/O resource contention failure

Patch-mainline: v5.8-rc7

Git-commit: 3f0dcfbcd2e162fc0a11c1f59b7acd42ee45f126

References: bsc#1186416

I/O requests may be held in scheduler queue because of resource contention.

The starvation scenario was handled properly in the regular completion

path but we failed to account for it during I/O submission. This lead to

the hang captured below. Make sure we run the queue when resource

contention is encountered in the submission path.

[   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

Link: https://lore.kernel.org/r/20200720025435.812030-1-ming.lei@redhat.com

Cc: linux-block@vger.kernel.org

Cc: Christoph Hellwig <hch@lst.de>

Reviewed-by: Bart Van Assche <bvanassche@acm.org>

Reviewed-by: Christoph Hellwig <hch@lst.de>

Signed-off-by: Ming Lei <ming.lei@redhat.com>

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Acked-by: Daniel Wagner <dwagner@suse.de>

---

 drivers/scsi/scsi_lib.c |   16 +++++++++++-----

 1 file changed, 11 insertions(+), 5 deletions(-)

--- a/drivers/scsi/scsi_lib.c

+++ b/drivers/scsi/scsi_lib.c

@@ -568,6 +568,15 @@ static void scsi_mq_uninit_cmd(struct sc

 	scsi_del_cmd_from_list(cmd);

 }

+static void scsi_run_queue_async(struct scsi_device *sdev)

+{

+	if (scsi_target(sdev)->single_lun ||

+	    !list_empty(&sdev->host->starved_list))

+		kblockd_schedule_work(&sdev->requeue_work);

+	else

+		blk_mq_run_hw_queues(sdev->request_queue, true);

+}

+

 /* Returns false when no more bytes to process, true if there are more */

 static bool scsi_end_request(struct request *req, blk_status_t error,

 		unsigned int bytes)

@@ -612,11 +621,7 @@ static bool scsi_end_request(struct requ

 	__blk_mq_end_request(req, error);

-	if (scsi_target(sdev)->single_lun ||

-	    !list_empty(&sdev->host->starved_list))

-		kblockd_schedule_work(&sdev->requeue_work);

-	else

-		blk_mq_run_hw_queues(q, true);

+	scsi_run_queue_async(sdev);

 	percpu_ref_put(&q->q_usage_counter);

 	return false;

@@ -1726,6 +1731,7 @@ static blk_status_t scsi_queue_rq(struct

 		 */

 		if (req->rq_flags & RQF_DONTPREP)

 			scsi_mq_uninit_cmd(cmd);

+		scsi_run_queue_async(sdev);

 		break;

 	}

 	return ret;