From: Ming Lei <ming.lei@xxxxxxxxxx> [ Upstream commit 3f0dcfbcd2e162fc0a11c1f59b7acd42ee45f126 ] 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@xxxxxxxxxx Cc: linux-block@xxxxxxxxxxxxxxx Cc: Christoph Hellwig <hch@xxxxxx> Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/scsi/scsi_lib.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index b8b4366f12001..887b6a47f5dac 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -564,6 +564,15 @@ static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd) scsi_uninit_cmd(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) @@ -608,11 +617,7 @@ static bool scsi_end_request(struct request *req, blk_status_t error, __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; @@ -1706,6 +1711,7 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx, */ if (req->rq_flags & RQF_DONTPREP) scsi_mq_uninit_cmd(cmd); + scsi_run_queue_async(sdev); break; } return ret; -- 2.25.1
