Re: [PATCH] block: mark GFP_NOIO around sysfs ->store()

[Ming Lei <ming.lei@redhat.com>]

On Wed, Aug 06, 2025 at 10:50:49AM +0800, xu.xin16@zte.com.cn wrote:
> > sysfs ->store is called with queue freezed, meantime we have several
> > ->store() callbacks(update_nr_requests, wbt, scheduler) to allocate
> > memory with GFP_KERNEL which may run into direct reclaim code path,
> > then potential deadlock can be caused.
> > 
> > Fix the issue by marking NOIO around sysfs ->store()
> > 
> > Reported-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Ming Lei <ming.lei@redhat.com>
> > ---
> >  block/blk-sysfs.c | 3 +++
> >  1 file changed, 3 insertions(+)
> 
> Excuse me, does the issue to fix comes from f1be1788a32e ("block: model freeze &
> enter queue as lock for supporting lockdep") ?

The above commit just starts to show the potential deadlock risk, which exists for
long time.

And now it becomes not necessary because blk_mq_freeze_queue() includes
memalloc_noio_save().

 
Thanks,
Ming