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 <shinichiro.kawasaki@xxxxxxx>
---
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;
+ }
+
+ 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))
+ 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;
}
--
2.34.1
