[PATCH] nvme: unquiesce the queue before cleaup it
Max Gurtovoy
maxg at mellanox.com
Thu Apr 26 03:23:47 PDT 2018
Hi Jianchao,
I actually tried this scenario with real HW and was able to repro the hang.
Unfortunatly, after applying your patch I got NULL deref:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000014
WARNING: CPU: 5 PID: 0 at block/blk-mq.c:526
__blk_mq_complete_request+0x154/0x160
I guess it's the same issue the IsraelR/Bart/Ming are trying to fix in
the block layer regarding completing requests.
I'll add IsraelR proposed fix to nvme-rdma that is currently on hold and
see what happens.
Nontheless, I don't like the situation that the reset and delete flows
can run concurrently.
-Max.
On 4/26/2018 11:27 AM, jianchao.wang wrote:
> 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 at 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 at 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 at 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_remove nvme_reset_work
>>>>>>> -> change state to DELETING
>>>>>>> -> fail to change state to LIVE
>>>>>>> -> nvme_remove_dead_ctrl
>>>>>>> -> nvme_dev_disable
>>>>>>> -> quiesce request_queue
>>>>>>> -> queue remove_work
>>>>>>> -> cancel_work_sync reset_work
>>>>>>> -> nvme_remove_namespaces
>>>>>>> -> splice ctrl->namespaces
>>>>>>> nvme_remove_dead_ctrl_work
>>>>>>> -> nvme_kill_queues
>>>>>>> -> nvme_ns_remove do nothing
>>>>>>> -> blk_cleanup_queue
>>>>>>> -> 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 at oracle.com>
>>>>>>> ---
>>>>>>> drivers/nvme/host/core.c | 9 ++++++++-
>>>>>>> 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)
>>>>>>> list_splice_init(&ctrl->namespaces, &ns_list);
>>>>>>> up_write(&ctrl->namespaces_rwsem);
>>>>>>> - list_for_each_entry_safe(ns, next, &ns_list, list)
>>>>>>> + /*
>>>>>>> + * After splice the namespaces list from the ctrl->namespaces,
>>>>>>> + * nobody could get them anymore, let's unquiesce the request_queue
>>>>>>> + * forcibly to avoid io hang.
>>>>>>> + */
>>>>>>> + list_for_each_entry_safe(ns, next, &ns_list, list) {
>>>>>>> + blk_mq_unquiesce_queue(ns->queue);
>>>>>>> nvme_ns_remove(ns);
>>>>>>> + }
>>>>>>> }
>>>>>>> EXPORT_SYMBOL_GPL(nvme_remove_namespaces);
>>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> Linux-nvme mailing list
>>>>>> Linux-nvme at lists.infradead.org
>>>>>> https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.infradead.org_mailman_listinfo_linux-2Dnvme&d=DwICAg&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=7WdAxUBeiTUTCy8v-7zXyr4qk7sx26ATvfo6QSTvZyQ&m=eQ9q70WFDS-d0s-KndBw8MOJvcBM6wuuKUNklqTC3h8&s=oBasfz9JoJw4yQF4EaWcNfKChZ1HMCkfHVZqyjvYVHQ&e=
>>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Linux-nvme mailing list
>>>>> Linux-nvme at lists.infradead.org
>>>>> https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.infradead.org_mailman_listinfo_linux-2Dnvme&d=DwICAg&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=7WdAxUBeiTUTCy8v-7zXyr4qk7sx26ATvfo6QSTvZyQ&m=eQ9q70WFDS-d0s-KndBw8MOJvcBM6wuuKUNklqTC3h8&s=oBasfz9JoJw4yQF4EaWcNfKChZ1HMCkfHVZqyjvYVHQ&e=
>>>>>
>>
>> _______________________________________________
>> Linux-nvme mailing list
>> Linux-nvme at lists.infradead.org
>> https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.infradead.org_mailman_listinfo_linux-2Dnvme&d=DwIGaQ&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=7WdAxUBeiTUTCy8v-7zXyr4qk7sx26ATvfo6QSTvZyQ&m=ivKrSi6co_9l91-czj52P2ABAPyKOwv9GrD3UeCbhio&s=2U00IBVk4CVt0Q-jiZX3sEWEEA2IleOjPU_PD38Fgvg&e=
>>
More information about the Linux-nvme
mailing list