diff options
author | Jens Axboe <axboe@kernel.dk> | 2022-06-21 19:03:57 +0300 |
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committer | Jens Axboe <axboe@kernel.dk> | 2022-06-21 19:59:58 +0300 |
commit | 2645672ffe21f0a1c139bfbc05ad30fd4e4f2583 (patch) | |
tree | 71cff81d1e2aa899d00cf7117f3be44b9f6a944a /block | |
parent | 9243fc4cd28c8bdddd7fe0abd5bbec3c4fdf5052 (diff) | |
download | linux-2645672ffe21f0a1c139bfbc05ad30fd4e4f2583.tar.xz |
block: pop cached rq before potentially blocking rq_qos_throttle()
If rq_qos_throttle() ends up blocking, then we will have invalidated and
flushed our current plug. Since blk_mq_get_cached_request() hasn't
popped the cached request off the plug list just yet, we end holding a
pointer to a request that is no longer valid. This insta-crashes with
rq->mq_hctx being NULL in the validity checks just after.
Pop the request off the cached list before doing rq_qos_throttle() to
avoid using a potentially stale request.
Fixes: 0a5aa8d161d1 ("block: fix blk_mq_attempt_bio_merge and rq_qos_throttle protection")
Reported-by: Dylan Yudaken <dylany@fb.com>
Tested-by: Dylan Yudaken <dylany@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r-- | block/blk-mq.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c index 33145ba52c96..93d9d60980fb 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2765,15 +2765,20 @@ static inline struct request *blk_mq_get_cached_request(struct request_queue *q, 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)) return NULL; - rq->cmd_flags = (*bio)->bi_opf; + /* + * If any qos ->throttle() end up blocking, we will have flushed the + * plug and hence killed the cached_rq list as well. Pop this entry + * before we throttle. + */ plug->cached_rq = rq_list_next(rq); + rq_qos_throttle(q, *bio); + + rq->cmd_flags = (*bio)->bi_opf; INIT_LIST_HEAD(&rq->queuelist); return rq; } |