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SubjectRe: linux 4.19.19: md0_raid:1317 blocked for more than 120 seconds.
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On 2/12/19 7:20 PM, Wolfgang Walter wrote:
> Am Dienstag, 12. Februar 2019, 16:20:11 schrieb Guoqing Jiang:
>> On 2/11/19 11:12 PM, Wolfgang Walter wrote:
>>> With 4.19.19 we see sometimes the following issue (practically only with
>>> blk_mq, though):
>>>
>>> Feb 4 20:04:46 tettnang kernel: [252300.060165] INFO: task md0_raid1:317
>>> blocked for more than 120 seconds. Feb 4 20:04:46 tettnang kernel:
>>> [252300.060188] Not tainted 4.19.19-debian64.all+1.1 #1 Feb 4
>>> 20:04:46 tettnang kernel: [252300.060197] "echo 0 >
>>> /proc/sys/kernel/hung_task_timeout_secs" disables this message. Feb 4
>>> 20:04:46 tettnang kernel: [252300.060207] md0_raid1 D 0 317
>>> 2 0x80000000 Feb 4 20:04:46 tettnang kernel: [252300.060211] Call
>>> Trace:
>>> Feb 4 20:04:46 tettnang kernel: [252300.060222] ? __schedule+0x2a2/0x8c0
>>> Feb 4 20:04:46 tettnang kernel: [252300.060226] ?
>>> _raw_spin_unlock_irqrestore+0x20/0x40 Feb 4 20:04:46 tettnang kernel:
>>> [252300.060229] schedule+0x32/0x90 Feb 4 20:04:46 tettnang kernel:
>>> [252300.060241] md_super_wait+0x69/0xa0 [md_mod] Feb 4 20:04:46
>>> tettnang kernel: [252300.060247] ? finish_wait+0x80/0x80 Feb 4 20:04:46
>>> tettnang kernel: [252300.060255] md_bitmap_wait_writes+0x8e/0xa0
>>> [md_mod] Feb 4 20:04:46 tettnang kernel: [252300.060263] ?
>>> md_bitmap_get_counter+0x42/0xd0 [md_mod] Feb 4 20:04:46 tettnang kernel:
>>> [252300.060271] md_bitmap_daemon_work+0x1e8/0x380 [md_mod] Feb 4
>>> 20:04:46 tettnang kernel: [252300.060278] ? md_rdev_init+0xb0/0xb0
>>> [md_mod] Feb 4 20:04:46 tettnang kernel: [252300.060285]
>>> md_check_recovery+0x26/0x540 [md_mod] Feb 4 20:04:46 tettnang kernel:
>>> [252300.060290] raid1d+0x5c/0xf00 [raid1] Feb 4 20:04:46 tettnang
>>> kernel: [252300.060294] ? preempt_count_add+0x79/0xb0 Feb 4 20:04:46
>>> tettnang kernel: [252300.060298] ? lock_timer_base+0x67/0x80 Feb 4
>>> 20:04:46 tettnang kernel: [252300.060302] ?
>>> _raw_spin_unlock_irqrestore+0x20/0x40 Feb 4 20:04:46 tettnang kernel:
>>> [252300.060304] ? try_to_del_timer_sync+0x4d/0x80 Feb 4 20:04:46
>>> tettnang kernel: [252300.060306] ? del_timer_sync+0x35/0x40 Feb 4
>>> 20:04:46 tettnang kernel: [252300.060309] ? schedule_timeout+0x17a/0x3b0
>>> Feb 4 20:04:46 tettnang kernel: [252300.060312] ?
>>> preempt_count_add+0x79/0xb0 Feb 4 20:04:46 tettnang kernel:
>>> [252300.060315] ? _raw_spin_lock_irqsave+0x25/0x50 Feb 4 20:04:46
>>> tettnang kernel: [252300.060321] ? md_rdev_init+0xb0/0xb0 [md_mod] Feb
>>> 4 20:04:46 tettnang kernel: [252300.060327] ? md_thread+0xf9/0x160
>>> [md_mod] Feb 4 20:04:46 tettnang kernel: [252300.060330] ?
>>> r1bio_pool_alloc+0x20/0x20 [raid1] Feb 4 20:04:46 tettnang kernel:
>>> [252300.060336] md_thread+0xf9/0x160 [md_mod] Feb 4 20:04:46 tettnang
>>> kernel: [252300.060340] ? finish_wait+0x80/0x80 Feb 4 20:04:46 tettnang
>>> kernel: [252300.060344] kthread+0x112/0x130 Feb 4 20:04:46 tettnang
>>> kernel: [252300.060346] ? kthread_create_worker_on_cpu+0x70/0x70 Feb 4
>>> 20:04:46 tettnang kernel: [252300.060350] ret_from_fork+0x35/0x40
>>>
>>> I saw that there was a similar problem with raid10 and an upstream patch
>>>
>>> e820d55cb99dd93ac2dc949cf486bb187e5cd70d
>>> md: fix raid10 hang issue caused by barrier
>>> by Guoqing Jiang
>>>
>>> I wonder if there is a similar fix needed for raid1?
>> Seems not, the calltrace tells the previous write superblock IO was not
>> finish as expected,
>> there is a report for raid5 which has similar problem with md_super_wait
>> in the link [1]. Maybe
>> you can disable blk-mq to narrow down the issue as well.
> I already did for 4 weeks. I didn't saw this with blk-mq disabled (for scsi
> and md), though this may be by luck.

Then I guess it maybe related to blk-mq, which scheduler are you used
with blk-mq?
And maybe you can switch it to see if it is caused by specified
scheduler or not.

>> [1] |https://bbs.archlinux.org/viewtopic.php?id=243520
> I found this bug report in debian:
>
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=904822

Thanks, the bug report also said it didn't happen after disable blk-mq.

Regards,
Guoqing

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