This is a note to let you know that I've just added the patch titled block: blk_queue_enter() / __bio_queue_enter() must return -EAGAIN for nowait to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: block-blk_queue_enter-__bio_queue_enter-must-return-.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit d2fdbf144987da632fbf09374518091755a1d71d Author: Stefan Roesch <shr@xxxxxx> Date: Mon Sep 12 09:53:25 2022 -0700 block: blk_queue_enter() / __bio_queue_enter() must return -EAGAIN for nowait [ Upstream commit 56f99b8d06ef1ed1c9730948f9f05ac2b930a20b ] Today blk_queue_enter() and __bio_queue_enter() return -EBUSY for the nowait code path. This is not correct: they should return -EAGAIN instead. This problem was detected by fio. The following command exposed the above problem: t/io_uring -p0 -d128 -b4096 -s32 -c32 -F1 -B0 -R0 -X1 -n24 -P1 -u1 -O0 /dev/ng0n1 By applying the patch, the retry case is handled correctly in the slow path. Signed-off-by: Stefan Roesch <shr@xxxxxx> Fixes: bfd343aa1718 ("blk-mq: don't wait in blk_mq_queue_enter() if __GFP_WAIT isn't set") Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/block/blk-core.c b/block/blk-core.c index 5009b9f1c3c9..13e1fca1e923 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -447,7 +447,7 @@ int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) while (!blk_try_enter_queue(q, pm)) { if (flags & BLK_MQ_REQ_NOWAIT) - return -EBUSY; + return -EAGAIN; /* * read pair of barrier in blk_freeze_queue_start(), we need to @@ -478,7 +478,7 @@ static inline int bio_queue_enter(struct bio *bio) if (test_bit(GD_DEAD, &disk->state)) goto dead; bio_wouldblock_error(bio); - return -EBUSY; + return -EAGAIN; } /*