Re: [PATCH] nvme: unquiesce the queue before cleaup it
From: jianchao.wang
Date: Thu Apr 26 2018 - 04:29:06 EST
Hi Max
I did a similar test on nvme-rdma, the underlying fabric is soft-RoCE.
A io loop, reset controller loop and a delete/create controller loop.
And found io hang below:
[ 230.884590] WARNING: CPU: 0 PID: 150 at /home/will/u04/source_code/linux-stable/drivers/nvme/host/rdma.c:1755 nvme_rdma_reset_ctrl_work+0x3d/0xb0 [nvme_rdma]
[ 230.884689] CPU: 0 PID: 150 Comm: kworker/u16:3 Not tainted 4.17.0-rc1+ #16
[ 230.884690] Hardware name: LENOVO 10MLS0E339/3106, BIOS M1AKT22A 06/27/2017
[ 230.884693] Workqueue: nvme-reset-wq nvme_rdma_reset_ctrl_work [nvme_rdma]
[ 230.884696] RIP: 0010:nvme_rdma_reset_ctrl_work+0x3d/0xb0 [nvme_rdma]
[ 230.884697] RSP: 0018:ffffa9e30255be40 EFLAGS: 00010246
[ 230.884699] RAX: 0000000000000000 RBX: ffff9633b64c2000 RCX: 0000000000000000
[ 230.884700] RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffffffff9ac05516
[ 230.884701] RBP: ffff9633b64c23b8 R08: 0000000000000001 R09: 0000000000000000
[ 230.884702] R10: 0000000000000000 R11: 0000000000000000 R12: ffff9633b64c2970
[ 230.884703] R13: 0000000000000000 R14: 0ffff96340ffcc80 R15: ffff9634102af9c0
[ 230.884705] FS: 0000000000000000(0000) GS:ffff963422c00000(0000) knlGS:0000000000000000
[ 230.884706] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 230.884707] CR2: 0000000001ce9ca4 CR3: 000000038040f005 CR4: 00000000003606f0
[ 230.884708] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 230.884709] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 230.884710] Call Trace:
[ 230.884717] process_one_work+0x1c0/0x680
[ 230.884722] worker_thread+0x22b/0x430
[ 230.884728] kthread+0x100/0x140
[ 230.884730] ? rescuer_thread+0x370/0x370
[ 230.884731] ? kthread_delayed_work_timer_fn+0x80/0x80
[ 230.884736] ret_from_fork+0x24/0x30
[ 230.884744] Code: ff 48 8d ab b8 03 00 00 48 89 ef e8 1e 25 d7 d9 31 f6 48 89 df e8 44 f9 ff ff be 04 00 00 00 48 89 ef e8 b7 13 d7 d9 84 c0 75 07 <0f> 0b 5b 5d 41 5c c3 31 f6 48 89 df e8 b2 fa ff ff 85 c0 75 39
[ 230.884799] irq event stamp: 88150
[ 230.884802] hardirqs last enabled at (88149): [<ffffffff9ac05529>] _raw_spin_unlock_irqrestore+0x59/0x70
[ 230.884803] hardirqs last disabled at (88150): [<ffffffff9ae0116c>] error_entry+0x6c/0xc0
[ 230.884805] softirqs last enabled at (87998): [<ffffffff9aa603a0>] sk_common_release+0x60/0xd0
[ 230.884807] softirqs last disabled at (87996): [<ffffffff9aa60375>] sk_common_release+0x35/0xd0
[ 230.884808] ---[ end trace c03fac253b80d77d ]---
[ 277.472094] INFO: task kworker/u16:0:6 blocked for more than 30 seconds.
[ 277.473482] Tainted: G W 4.17.0-rc1+ #16
[ 277.474825] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 277.476293] kworker/u16:0 D 0 6 2 0x80000000
[ 277.476317] Workqueue: nvme-delete-wq nvme_delete_ctrl_work
[ 277.476335] Call Trace:
[ 277.476365] ? __schedule+0x3de/0xac0
[ 277.476393] schedule+0x3c/0x90
[ 277.476405] blk_mq_freeze_queue_wait+0x44/0x90
[ 277.476419] ? wait_woken+0x90/0x90
[ 277.476437] blk_cleanup_queue+0xe1/0x280
[ 277.476453] nvme_ns_remove+0x1c8/0x260
[ 277.476475] nvme_remove_namespaces+0x7f/0xa0
[ 277.476495] nvme_delete_ctrl_work+0x4b/0x80
[ 277.476508] process_one_work+0x1c0/0x680
[ 277.476535] worker_thread+0x22b/0x430
[ 277.476562] kthread+0x100/0x140
[ 277.476572] ? rescuer_thread+0x370/0x370
[ 277.476579] ? kthread_delayed_work_timer_fn+0x80/0x80
[ 277.476598] ret_from_fork+0x24/0x30
00000000ea33345b {.op=READ, .cmd_flags=23, .rq_flags=MQ_INFLIGHT|IO_STAT, .state=idle, .tag=19, .internal_tag=-1}
0000000071218c5a {.op=READ, .cmd_flags=23, .rq_flags=MQ_INFLIGHT|IO_STAT, .state=idle, .tag=45, .internal_tag=-1}
root@will-ThinkCentre-M910s:/sys/kernel/debug/block/nvme1c1n1# cat state
DYING|BYPASS|NOMERGES|SAME_COMP|NONROT|IO_STAT|DISCARD|NOXMERGES|INIT_DONE|NO_SG_MERGE|POLL|WC|FUA|STATS|QUIESCED
This is due to a race following:
nvme_delete_ctrl nvme_rdma_reset_ctrl_work
-> change state to DELETING
-> queue delete_work
-> nvme_rdma_shutdown_ctrl
-> nvme_stop_queues
-> blk_mq_quiesce_queue
-> change to LIVE state fails
-> return
nvme_delete_ctrl_work
-> nvme_remove_namespaces
-> nvme_ns_remove
-> blk_cleanup_queue
-> blk_freeze_queue
This patch could also fix this issue.
Thanks
Jianchao
On 04/22/2018 11:00 PM, jianchao.wang wrote:
> Hi Max
>
> That's really appreciated!
> Here is my test script.
>
> loop_reset_controller.sh
> #!/bin/bash
> while true
> do
> echo 1 > /sys/block/nvme0n1/device/reset_controller
> sleep 1
> done
>
> loop_unbind_driver.sh
> #!/bin/bash
> while true
> do
> echo "0000:02:00.0" > /sys/bus/pci/drivers/nvme/unbind
> sleep 2
> echo "0000:02:00.0" > /sys/bus/pci/drivers/nvme/bind
> sleep 2
> done
>
> loop_io.sh
> #!/bin/bash
>
> file="/dev/nvme0n1"
> echo $file
> while true;
> do
> if [ -e $file ];then
> fio fio_job_rand_read.ini
> else
> echo "Not found"
> sleep 1
> fi
> done
>
> The fio jobs is as below:
> size=512m
> rw=randread
> bs=4k
> ioengine=libaio
> iodepth=64
> direct=1
> numjobs=16
> filename=/dev/nvme0n1
> group_reporting
>
> I started in sequence, loop_io.sh, loop_reset_controller.sh, loop_unbind_driver.sh.
> And if lucky, I will get io hang in 3 minutes. ;)
> Such as:
>
> [ 142.858074] nvme nvme0: pci function 0000:02:00.0
> [ 144.972256] nvme nvme0: failed to mark controller state 1
> [ 144.972289] nvme nvme0: Removing after probe failure status: 0
> [ 185.312344] INFO: task bash:1673 blocked for more than 30 seconds.
> [ 185.312889] Not tainted 4.17.0-rc1+ #6
> [ 185.312950] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ 185.313049] bash D 0 1673 1629 0x00000080
> [ 185.313061] Call Trace:
> [ 185.313083] ? __schedule+0x3de/0xac0
> [ 185.313103] schedule+0x3c/0x90
> [ 185.313111] blk_mq_freeze_queue_wait+0x44/0x90
> [ 185.313123] ? wait_woken+0x90/0x90
> [ 185.313133] blk_cleanup_queue+0xe1/0x280
> [ 185.313145] nvme_ns_remove+0x1c8/0x260
> [ 185.313159] nvme_remove_namespaces+0x7f/0xa0
> [ 185.313170] nvme_remove+0x6c/0x130
> [ 185.313181] pci_device_remove+0x36/0xb0
> [ 185.313193] device_release_driver_internal+0x160/0x230
> [ 185.313205] unbind_store+0xfe/0x150
> [ 185.313219] kernfs_fop_write+0x114/0x190
> [ 185.313234] __vfs_write+0x23/0x150
> [ 185.313246] ? rcu_read_lock_sched_held+0x3f/0x70
> [ 185.313252] ? preempt_count_sub+0x92/0xd0
> [ 185.313259] ? __sb_start_write+0xf8/0x200
> [ 185.313271] vfs_write+0xc5/0x1c0
> [ 185.313284] ksys_write+0x45/0xa0
> [ 185.313298] do_syscall_64+0x5a/0x1a0
> [ 185.313308] entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> And get following information in block debugfs:
> root@will-ThinkCentre-M910s:/sys/kernel/debug/block/nvme0n1# cat hctx6/cpu6/rq_list
> 000000001192d19b {.op=READ, .cmd_flags=, .rq_flags=IO_STAT, .state=idle, .tag=69, .internal_tag=-1}
> 00000000c33c8a5b {.op=READ, .cmd_flags=, .rq_flags=IO_STAT, .state=idle, .tag=78, .internal_tag=-1}
> root@will-ThinkCentre-M910s:/sys/kernel/debug/block/nvme0n1# cat state
> DYING|BYPASS|NOMERGES|SAME_COMP|NONROT|IO_STAT|DISCARD|NOXMERGES|INIT_DONE|NO_SG_MERGE|POLL|WC|FUA|STATS|QUIESCED
>
> We can see there were reqs on ctx rq_list and the request_queue is QUIESCED.
>
> Thanks again !!
> Jianchao
>
> On 04/22/2018 10:48 PM, Max Gurtovoy wrote:
>>
>>
>> On 4/22/2018 5:25 PM, jianchao.wang wrote:
>>> Hi Max
>>>
>>> No, I only tested it on PCIe one.
>>> And sorry for that I didn't state that.
>>
>> Please send your exact test steps and we'll run it using RDMA transport.
>> I also want to run a mini regression on this one since it may effect other flows.
>>
>>>
>>> Thanks
>>> Jianchao
>>>
>>> On 04/22/2018 10:18 PM, Max Gurtovoy wrote:
>>>> Hi Jianchao,
>>>> Since this patch is in the core, have you tested it using some fabrics drives too ? RDMA/FC ?
>>>>
>>>> thanks,
>>>> Max.
>>>>
>>>> On 4/22/2018 4:32 PM, jianchao.wang wrote:
>>>>> Hi keith
>>>>>
>>>>> Would you please take a look at this patch.
>>>>>
>>>>> This issue could be reproduced easily with a driver bind/unbind loop,
>>>>> a reset loop and a IO loop at the same time.
>>>>>
>>>>> Thanks
>>>>> Jianchao
>>>>>
>>>>> On 04/19/2018 04:29 PM, Jianchao Wang wrote:
>>>>>> There is race between nvme_remove and nvme_reset_work that can
>>>>>> lead to io hang.
>>>>>>
>>>>>> nvme_removeÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ nvme_reset_work
>>>>>> -> change state to DELETING
>>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ -> fail to change state to LIVE
>>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ -> nvme_remove_dead_ctrl
>>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ -> nvme_dev_disable
>>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ -> quiesce request_queue
>>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ -> queue remove_work
>>>>>> -> cancel_work_sync reset_work
>>>>>> -> nvme_remove_namespaces
>>>>>> ÂÂÂ -> splice ctrl->namespaces
>>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ nvme_remove_dead_ctrl_work
>>>>>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ -> nvme_kill_queues
>>>>>> ÂÂÂ -> nvme_ns_removeÂÂÂÂÂÂÂÂÂÂÂÂÂÂ do nothing
>>>>>> ÂÂÂÂÂ -> blk_cleanup_queue
>>>>>> ÂÂÂÂÂÂÂ -> blk_freeze_queue
>>>>>> Finally, the request_queue is quiesced state when wait freeze,
>>>>>> we will get io hang here.
>>>>>>
>>>>>> To fix it, unquiesce the request_queue directly before nvme_ns_remove.
>>>>>> We have spliced the ctrl->namespaces, so nobody could access them
>>>>>> and quiesce the queue any more.
>>>>>>
>>>>>> Signed-off-by: Jianchao Wang <jianchao.w.wang@xxxxxxxxxx>
>>>>>> ---
>>>>>> ÂÂ drivers/nvme/host/core.c | 9 ++++++++-
>>>>>> ÂÂ 1 file changed, 8 insertions(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
>>>>>> index 9df4f71..0e95082 100644
>>>>>> --- a/drivers/nvme/host/core.c
>>>>>> +++ b/drivers/nvme/host/core.c
>>>>>> @@ -3249,8 +3249,15 @@ void nvme_remove_namespaces(struct nvme_ctrl *ctrl)
>>>>>> ÂÂÂÂÂÂ list_splice_init(&ctrl->namespaces, &ns_list);
>>>>>> ÂÂÂÂÂÂ up_write(&ctrl->namespaces_rwsem);
>>>>>> ÂÂ -ÂÂÂ list_for_each_entry_safe(ns, next, &ns_list, list)
>>>>>> +ÂÂÂ /*
>>>>>> +ÂÂÂÂ * After splice the namespaces list from the ctrl->namespaces,
>>>>>> +ÂÂÂÂ * nobody could get them anymore, let's unquiesce the request_queue
>>>>>> +ÂÂÂÂ * forcibly to avoid io hang.
>>>>>> +ÂÂÂÂ */
>>>>>> +ÂÂÂ list_for_each_entry_safe(ns, next, &ns_list, list) {
>>>>>> +ÂÂÂÂÂÂÂ blk_mq_unquiesce_queue(ns->queue);
>>>>>> ÂÂÂÂÂÂÂÂÂÂ nvme_ns_remove(ns);
>>>>>> +ÂÂÂ }
>>>>>> ÂÂ }
>>>>>> ÂÂ EXPORT_SYMBOL_GPL(nvme_remove_namespaces);
>>>>>> Â
>>>>>
>>>>> _______________________________________________
>>>>> Linux-nvme mailing list
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>>>>>
>>>>
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