Re: I/O hangs after resuming from suspend-to-ram

Martin Steigerwald
2017-08-28T13:10:39Z

Ming Lei - 28.08.17, 20:58:
> On Sun, Aug 27, 2017 at 09:43:52AM +0200, Oleksandr Natalenko wrote:
> > Hi.
> >
> > Here is disk setup for QEMU VM:
> >
> > ===
> > [root@archmq ~]# smartctl -i /dev/sda
> > …
> > Device Model: QEMU HARDDISK
> > Serial Number: QM00001
> > Firmware Version: 2.5+
> > User Capacity: 4,294,967,296 bytes [4.29 GB]
> > Sector Size: 512 bytes logical/physical
> > Device is: Not in smartctl database [for details use: -P showall]
> > ATA Version is: ATA/ATAPI-7, ATA/ATAPI-5 published, ANSI NCITS 340-2000
> > Local Time is: Sun Aug 27 09:31:54 2017 CEST
> > SMART support is: Available - device has SMART capability.
> > SMART support is: Enabled
> >
> > [root@archmq ~]# lsblk
> > NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
> > sda 8:0 0 4G 0 disk
> > `-sda1 8:1 0 4G 0 part
> >
> > `-md0 9:0 0 4G 0 raid10
> >
> > `-system 253:0 0 4G 0 crypt
> >
> > |-system-boot 253:1 0 512M 0 lvm /boot
> > |-system-swap 253:2 0 512M 0 lvm [SWAP]
> >
> > `-system-root 253:3 0 3G 0 lvm /
> >
> > sdb 8:16 0 4G 0 disk
> > `-sdb1 8:17 0 4G 0 part
> >
> > `-md0 9:0 0 4G 0 raid10
> >
> > `-system 253:0 0 4G 0 crypt
> >
> > |-system-boot 253:1 0 512M 0 lvm /boot
> > |-system-swap 253:2 0 512M 0 lvm [SWAP]
> >
> > `-system-root 253:3 0 3G 0 lvm /
> >
> > sr0 11:0 1 1024M 0 rom
> >
> > [root@archmq ~]# mdadm --misc --detail /dev/md0
> >
> > /dev/md0:
> > Version : 1.2
> >
> > Creation Time : Sat Jul 29 16:37:05 2017
> >
> > Raid Level : raid10
> > Array Size : 4191232 (4.00 GiB 4.29 GB)
> >
> > Used Dev Size : 4191232 (4.00 GiB 4.29 GB)
> >
> > Raid Devices : 2
> >
> > Total Devices : 2
> >
> > Persistence : Superblock is persistent
> >
> > Update Time : Sun Aug 27 09:30:33 2017
> >
> > State : clean
> >
> > Active Devices : 2
> >
> > Working Devices : 2
> >
> > Failed Devices : 0
> >
> > Spare Devices : 0
> >
> > Layout : far=2
> >
> > Chunk Size : 512K
> >
> > Name : archiso:0
> > UUID : 43f4be59:c8d2fa0a:a94acdff:1c7f2f4e
> >
> > Events : 485
> >
> > Number Major Minor RaidDevice State
> >
> > 0 8 1 0 active sync /dev/sda1
> > 1 8 17 1 active sync /dev/sdb1
> >
> > ===
> >
> > In words: 2 virtual disks, RAID10 setup with far-2 layout, LUKS on it,
> > then
> > LVM, then ext4 for boot, swap and btrfs for /.
> >
> > I couldn't reproduce the issue with single disk without RAID.
>
> Could you verify if the following patch fixes your issue?

Could this also apply to non MD RAID systems? I am using BTRFS RAID
1 with two SSDs. So far with CFQ it runs stable.

Thanks,
Martin

> From 9fa53d708ebc1d5b87e62e542dc54272529da244 Mon Sep 17 00:00:00 2001
> From: Ming Lei <ming.lei@redhat.com>
> Date: Mon, 28 Aug 2017 19:59:08 +0800
> Subject: [PATCH] blk-mq: align to legacy path for implementing
> blk_execute_rq
>
> In legacy path, when one request is run via blk_execute_rq(),
> it is added to q->queue_head directly, and I/O scheduler's
> queue is bypassed because either merging or sorting isn't
> needed.
>
> When SCSI device is put into quiece state, such as during
> system suspend, we need to add the request of RQF_PM into
> head of the queue.
>
> This patch fixes I/O hang after system resume.
>
> Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
> block/blk-core.c | 2 +-
> block/blk-exec.c | 2 +-
> block/blk-flush.c | 2 +-
> block/blk-mq-sched.c | 58
> ++++++++++++++++++++++++++++++++++++++++++++++++++++ block/blk-mq-sched.h |
> 2 ++
> 5 files changed, 63 insertions(+), 3 deletions(-)
>
> diff --git a/block/blk-core.c b/block/blk-core.c
> index dbecbf4a64e0..fb75bc646ebc 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -2330,7 +2330,7 @@ blk_status_t blk_insert_cloned_request(struct
> request_queue *q, struct request * if (q->mq_ops) {
> if (blk_queue_io_stat(q))
> blk_account_io_start(rq, true);
> - blk_mq_sched_insert_request(rq, false, true, false, false);
> + blk_mq_sched_insert_request_bypass(rq, false, true, false, false);
> return BLK_STS_OK;
> }
>
> diff --git a/block/blk-exec.c b/block/blk-exec.c
> index 5c0f3dc446dc..4565aa6bb624 100644
> --- a/block/blk-exec.c
> +++ b/block/blk-exec.c
> @@ -61,7 +61,7 @@ void blk_execute_rq_nowait(struct request_queue *q, struct
> gendisk *bd_disk, * be reused after dying flag is set
> */
> if (q->mq_ops) {
> - blk_mq_sched_insert_request(rq, at_head, true, false, false);
> + blk_mq_sched_insert_request_bypass(rq, at_head, true, false, false);
> return;
> }
>
> diff --git a/block/blk-flush.c b/block/blk-flush.c
> index ed5fe322abba..51e89e5c525a 100644
> --- a/block/blk-flush.c
> +++ b/block/blk-flush.c
> @@ -463,7 +463,7 @@ void blk_insert_flush(struct request *rq)
> if ((policy & REQ_FSEQ_DATA) &&
> !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) {
> if (q->mq_ops)
> - blk_mq_sched_insert_request(rq, false, true, false, false);
> + blk_mq_sched_insert_request_bypass(rq, false, true, false, false);
> else
> list_add_tail(&rq->queuelist, &q->queue_head);
> return;
> diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
> index 4ab69435708c..eeeea026fb47 100644
> --- a/block/blk-mq-sched.c
> +++ b/block/blk-mq-sched.c
> @@ -354,6 +354,64 @@ static void blk_mq_sched_insert_flush(struct
> blk_mq_hw_ctx *hctx, blk_mq_add_to_requeue_list(rq, false, true);
> }
>
> +static void blk_mq_flush_hctx(struct blk_mq_hw_ctx *hctx,
> + struct elevator_queue *e,
> + const bool has_sched_dispatch,
> + struct list_head *rqs)
> +{
> + LIST_HEAD(list);
> +
> + if (!has_sched_dispatch)
> + blk_mq_flush_busy_ctxs(hctx, &list);
> + else {
> + while (true) {
> + struct request *rq;
> +
> + rq = e->type->ops.mq.dispatch_request(hctx);
> + if (!rq)
> + break;
> + list_add_tail(&rq->queuelist, &list);
> + }
> + }
> +
> + list_splice_tail(&list, rqs);
> +}
> +
> +void blk_mq_sched_insert_request_bypass(struct request *rq, bool at_head,
> + bool run_queue, bool async,
> + bool can_block)
> +{
> + struct request_queue *q = rq->q;
> + struct elevator_queue *e = q->elevator;
> + struct blk_mq_ctx *ctx = rq->mq_ctx;
> + struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, ctx->cpu);
> + LIST_HEAD(list);
> + const bool has_sched_dispatch = e && e->type->ops.mq.dispatch_request;
> +
> + if (rq->tag == -1 && op_is_flush(rq->cmd_flags)) {
> + blk_mq_sched_insert_flush(hctx, rq, can_block);
> + return;
> + }
> +
> + if (at_head)
> + list_add_tail(&rq->queuelist, &list);
> + else {
> + blk_mq_flush_hctx(hctx, e, has_sched_dispatch, &list);
> + list_add_tail(&rq->queuelist, &list);
> + run_queue = true;
> + }
> +
> + spin_lock(&hctx->lock);
> + if (at_head)
> + list_splice(&list, &hctx->dispatch);
> + else
> + list_splice_tail(&list, &hctx->dispatch);
> + spin_unlock(&hctx->lock);
> +
> + if (run_queue)
> + blk_mq_run_hw_queue(hctx, async);
> +}
> +
> void blk_mq_sched_insert_request(struct request *rq, bool at_head,
> bool run_queue, bool async, bool can_block)
> {
> diff --git a/block/blk-mq-sched.h b/block/blk-mq-sched.h
> index 9267d0b7c197..4d01697a627f 100644
> --- a/block/blk-mq-sched.h
> +++ b/block/blk-mq-sched.h
> @@ -18,6 +18,8 @@ void blk_mq_sched_restart(struct blk_mq_hw_ctx *hctx);
>
> void blk_mq_sched_insert_request(struct request *rq, bool at_head,
> bool run_queue, bool async, bool can_block);
> +void blk_mq_sched_insert_request_bypass(struct request *rq, bool at_head,
> + bool run_queue, bool async, bool can_block);
> void blk_mq_sched_insert_requests(struct request_queue *q,
> struct blk_mq_ctx *ctx,
> struct list_head *list, bool run_queue_async);

--
Martin