[dm-devel] A crash caused by the commit 0dd84b319352bb8ba64752d4e45396d8b13e6018

[Mikulas Patocka]

On Thu, 3 Nov 2022, Guoqing Jiang wrote:

> Hi,
> 
> On 11/3/22 12:27 AM, Mikulas Patocka wrote:
> > Hi
> > 
> > There's a crash in the test shell/lvchange-rebuild-raid.sh when running
> > the lvm testsuite. It can be reproduced by running "make check_local
> > T=shell/lvchange-rebuild-raid.sh" in a loop.
> 
> I have problem to run the cmd (not sure what I missed), it would be better if
> the relevant cmds are extracted from the script then I can reproduce it with
> those cmds directly.

Ask Zdenek Kabelac to help you with running the testsuite. He has better 
understanding of the testsuite than me.

> BTW, is the mempool_free from endio -> dec_count -> complete_io?
> And io which caused the crash is from dm_io -> async_io / sync_io
>  -> dispatch_io, seems dm-raid1 can call it instead of dm-raid, so I
> suppose the io is for mirror image.
> 
> Thanks,
> Guoqing

I presume that the bug is caused by destruction of a bio set while bio 
from that set was in progress. When the bio finishes and an attempt is 
made to free the bio, a crash happens when the code tries to free the bio 
into a destroyed mempool.

I can do more testing to validate this theory.

Mikulas