From: Ming Lei <ming.lei@xxxxxxxxxx> [ Upstream commit 19768f80cf23834e65482f1667ff54192d469fee ] It isn't correct to set set->nr_maps as 3 if g_poll_queues is > 0 since we can change it via configfs for null_blk device created there, so only set it as 3 if active poll_queues is > 0. Fixes divide zero exception reported by Shinichiro. Fixes: 2bfdbe8b7ebd ("null_blk: allow zero poll queues") Reported-by: Shinichiro Kawasaki <shinichiro.kawasaki@xxxxxxx> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> Reviewed-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@xxxxxxx> Link: https://lore.kernel.org/r/20211224010831.1521805-1-ming.lei@xxxxxxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/block/null_blk/main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c index fc1317060db54..e23aac1a83f73 100644 --- a/drivers/block/null_blk/main.c +++ b/drivers/block/null_blk/main.c @@ -1891,7 +1891,7 @@ static int null_init_tag_set(struct nullb *nullb, struct blk_mq_tag_set *set) if (g_shared_tag_bitmap) set->flags |= BLK_MQ_F_TAG_HCTX_SHARED; set->driver_data = nullb; - if (g_poll_queues) + if (poll_queues) set->nr_maps = 3; else set->nr_maps = 1; -- 2.34.1