On 2018/12/12 下午8:37, David Sterba wrote:
> On Wed, Dec 12, 2018 at 08:39:46AM +0800, Qu Wenruo wrote:
>> changelog:
>> v2:
>> - Rebase to v4.20-rc1.
>> - Instead commit transaction after each reloc tree merge, delay it until
>>   merge_reloc_roots() finishes.
>> - This provides a more natural behavior, and reduce the unnecessary
>>   transaction commits.
>> v3:
>> - Fix backref walk deadlock by not triggering it at all.
>>   This also removes the need for @exec_post refactor and replace the
>>   patch to allow @old_root unpopulated.
>> - Include the patch that fixes the unexpected data rsv free.
> 
> I've tested the deadlock fix but it still locks up and there are some
> lockdep warnings. I can't spend more time on that given the pre-merge
> window timing so I'm going to postpone all qgruop things until the next
> cycle.

No problem.

But would you please provide the reproducer?
My test script can't reproduce lockup this time.

Thanks,
Qu

> 
> The deadlock fix can go to a -rc independently, so once I'm able to
> gather logs I'll let you know.
>