[dm-devel] 答复: 答复: 答复: why command of multipath send reinstate message to all dm's paths

[Bart Van Assche]

On 07/02/18 02:20, Martin Wilck wrote:
> On Mon, 2018-07-02 at 08:53 +0000, Jiaojianbing wrote:
>> [ ... ]
>> and one of D process's stack:
>> # cat /proc/3659 /stack
>> [<ffffffff8118e784>] __lock_page+0x74/0x90
>> [<ffffffff811a0564>] truncate_inode_pages_range+0x704/0x740
>> [<ffffffff811a05b5>] truncate_inode_pages+0x15/0x20
>> [<ffffffff812519af>] kill_bdev+0x2f/0x40
>> [<ffffffff81253464>] __blkdev_put+0x64/0x1a0
>> [<ffffffff81253eee>] blkdev_put+0x4e/0x140
>> [<ffffffff81254095>] blkdev_close+0x25/0x30
>> [<ffffffff8121796c>] __fput+0xec/0x260
>> [<ffffffff81217c1e>] ____fput+0xe/0x10
>> [<ffffffff810b6867>] task_work_run+0xc7/0xe0
>> [<ffffffff81095010>] do_exit+0x2e0/0xa50
>> [<ffffffff810957ff>] do_group_exit+0x3f/0xa0
>> [<ffffffff810a6d60>] get_signal_to_deliver+0x1d0/0x6e0
>> [<ffffffff8102a527>] do_signal+0x57/0x6b0
>> [<ffffffff8102abdf>] do_notify_resume+0x5f/0xb0
>> [<ffffffff816c264f>] int_signal+0x12/0x17
>> [<ffffffffffffffff>] 0xffffffffffffffff
> 
> 
> Hmm, that stack reminds me of two situations Bart has reported earlier:
> 
> https://patchwork.kernel.org/patch/9261609/
> https://patchwork.kernel.org/patch/9202331/
> 
> It doesn't seem to me that there has been agreement on Bart's proposed
> fixes so far, but I may have missed it. Maybe Bart can comment on that.

Hello Martin,

The above call stack means that a block layer request got stuck. The two 
patches I posted before are not the right approach to fix this. As you 
maybe know rescan-scsi-bus.sh uses the sysfs "delete" attribute and 
writing into that attribute can trigger a deadlock. Have you noticed 
patch "Avoid that SCSI device removal through sysfs triggers a deadlock" 
(https://www.mail-archive.com/linux-scsi@vger.kernel.org/msg74500.html)? 
If the above lockup is reproducible with a kernel v4.17 or later and 
with that patch applied, it would help if a dump of the attributes under 
/sys/kernel/debug/block could be provided.

Bart.