Re: [PATCH] block: revert pushing the final release of request_queue to a workqueue.

[Bart Van Assche]

On 2020-02-06 03:10, yu kuai wrote:
> syzbot is reporting use after free bug in debugfs_remove[1].
> 
> This is because in request_queue, 'q->debugfs_dir' and
> 'q->blk_trace->dir' could be the same dir. And in __blk_release_queue(),
> blk_mq_debugfs_unregister() will remove everything inside the dir.

Hi Yu,

Have you already noticed patch "[PATCH] blktrace: Protect q->blk_trace
with RCU"? If not, have you already tried to verify whether that patch
fixes the use-after-free detected by syzbot? See also
https://lore.kernel.org/linux-block/BYAPR04MB57492F689BA17786A24F08EE86190@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/T/#mce8ffe534d93716f678d52178b4e34d4d1c3c597

Thanks,

Bart.