Commit 7c0be4ea authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

block: mark GFP_NOIO around sysfs ->store() 



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: default avatarThomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarJohn Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20250113015833.698458-1-ming.lei@redhat.com
Link: https://lore.kernel.org/linux-block/Z4RkemI9f6N5zoEF@fedora/T/#mc774c65eeca5c024d29695f9ac6152b87763f305


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 9752b550

block/blk-sysfs.c

+3 −0
Original line number Diff line number Diff line
@@ -681,6 +681,7 @@ queue_attr_store(struct kobject *kobj, struct attribute *attr, 
	struct queue_sysfs_entry *entry = to_queue(attr);

	struct gendisk *disk = container_of(kobj, struct gendisk, queue_kobj);

	struct request_queue *q = disk->queue;

	unsigned int noio_flag;

	ssize_t res;



	if (!entry->store_limit && !entry->store)
@@ -711,7 +712,9 @@ queue_attr_store(struct kobject *kobj, struct attribute *attr, 


	mutex_lock(&q->sysfs_lock);

	blk_mq_freeze_queue(q);

	noio_flag = memalloc_noio_save();

	res = entry->store(disk, page, length);

	memalloc_noio_restore(noio_flag);

	blk_mq_unfreeze_queue(q);

	mutex_unlock(&q->sysfs_lock);

	return res;