From 0a5aa8d161d19a1b12fd25b434b32f7c885c73bb Mon Sep 17 00:00:00 2001 From: Shin'ichiro Kawasaki Date: Tue, 8 Mar 2022 17:09:15 +0900 Subject: [PATCH] block: fix blk_mq_attempt_bio_merge and rq_qos_throttle protection Commit 9d497e2941c3 ("block: don't protect submit_bio_checks by q_usage_counter") moved blk_mq_attempt_bio_merge and rq_qos_throttle calls out of q_usage_counter protection. However, these functions require q_usage_counter protection. The blk_mq_attempt_bio_merge call without the protection resulted in blktests block/005 failure with KASAN null- ptr-deref or use-after-free at bio merge. The rq_qos_throttle call without the protection caused kernel hang at qos throttle. To fix the failures, move the blk_mq_attempt_bio_merge and rq_qos_throttle calls back to q_usage_counter protection. Fixes: 9d497e2941c3 ("block: don't protect submit_bio_checks by q_usage_counter") Signed-off-by: Shin'ichiro Kawasaki Link: https://lore.kernel.org/r/20220308080915.3473689-1-shinichiro.kawasaki@wdc.com Reviewed-by: Ming Lei Signed-off-by: Jens Axboe --- block/blk-mq.c | 35 +++++++++++++++++++++++------------ 1 file changed, 23 insertions(+), 12 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index d69ca91fbc8b..9a9185a0a2d1 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2718,7 +2718,8 @@ static bool blk_mq_attempt_bio_merge(struct request_queue *q, static struct request *blk_mq_get_new_requests(struct request_queue *q, struct blk_plug *plug, - struct bio *bio) + struct bio *bio, + unsigned int nsegs) { struct blk_mq_alloc_data data = { .q = q, @@ -2730,6 +2731,11 @@ static struct request *blk_mq_get_new_requests(struct request_queue *q, if (unlikely(bio_queue_enter(bio))) return NULL; + if (blk_mq_attempt_bio_merge(q, bio, nsegs)) + goto queue_exit; + + rq_qos_throttle(q, bio); + if (plug) { data.nr_tags = plug->nr_ios; plug->nr_ios = 1; @@ -2742,12 +2748,13 @@ static struct request *blk_mq_get_new_requests(struct request_queue *q, rq_qos_cleanup(q, bio); if (bio->bi_opf & REQ_NOWAIT) bio_wouldblock_error(bio); +queue_exit: blk_queue_exit(q); return NULL; } static inline struct request *blk_mq_get_cached_request(struct request_queue *q, - struct blk_plug *plug, struct bio *bio) + struct blk_plug *plug, struct bio **bio, unsigned int nsegs) { struct request *rq; @@ -2757,12 +2764,19 @@ static inline struct request *blk_mq_get_cached_request(struct request_queue *q, if (!rq || rq->q != q) return NULL; - if (blk_mq_get_hctx_type(bio->bi_opf) != rq->mq_hctx->type) + if (blk_mq_attempt_bio_merge(q, *bio, nsegs)) { + *bio = NULL; return NULL; - if (op_is_flush(rq->cmd_flags) != op_is_flush(bio->bi_opf)) + } + + rq_qos_throttle(q, *bio); + + if (blk_mq_get_hctx_type((*bio)->bi_opf) != rq->mq_hctx->type) + return NULL; + if (op_is_flush(rq->cmd_flags) != op_is_flush((*bio)->bi_opf)) return NULL; - rq->cmd_flags = bio->bi_opf; + rq->cmd_flags = (*bio)->bi_opf; plug->cached_rq = rq_list_next(rq); INIT_LIST_HEAD(&rq->queuelist); return rq; @@ -2800,14 +2814,11 @@ void blk_mq_submit_bio(struct bio *bio) if (!bio_integrity_prep(bio)) return; - if (blk_mq_attempt_bio_merge(q, bio, nr_segs)) - return; - - rq_qos_throttle(q, bio); - - rq = blk_mq_get_cached_request(q, plug, bio); + rq = blk_mq_get_cached_request(q, plug, &bio, nr_segs); if (!rq) { - rq = blk_mq_get_new_requests(q, plug, bio); + if (!bio) + return; + rq = blk_mq_get_new_requests(q, plug, bio, nr_segs); if (unlikely(!rq)) return; }