Re: NULL pointer dereference in blk_mq_put_rq_ref (LTS kernel 5.10.56)

On Mon, Aug 30, 2021 at 04:52:54PM +0200, Martin Svec wrote:

Hi all,

after upgrade from 5.4.x to 5.10.56 one of our LIO iSCSI Target servers hung
with kernel NULL pointer dereference bug, see below. According to the call trace
I guess that the bug is related to the generic blk-mq subsystem. I don't see any
fixes related to blk-mq between 5.10.56 and 5.10.60, so this bug probably occurs
in latest 5.10 stable releases too. I this a known issue or do you have any ideas
what's wrong?

The issue should have been fixed by the following two patches:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a9ed27a764156929efe714033edb3e9023c5f321
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c2da19ed50554ce52ecbad3655c98371fe58599f


Thanks,
Ming