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blk-mq: Avoid that submitting a bio concurrently with device removal triggers a crash 

Because blkcg_exit_queue() is now called from inside blk_cleanup_queue()
it is no longer safe to access cgroup information during or after the
blk_cleanup_queue() call. Hence protect the generic_make_request_checks()
call with blk_queue_enter() / blk_queue_exit().

Reported-by: Ming Lei <ming.lei@redhat.com>
Fixes: a063057d7c ("block: Fix a race between request queue removal and the block cgroup controller")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Bart Van Assche 2018-04-10 17:02:40 -06:00 committed by Jens Axboe
parent a93f00b376
commit 37f9579f4c
1 changed files with 29 additions and 6 deletions
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35
block/blk-core.c
View File

@ -2385,8 +2385,20 @@ blk_qc_t generic_make_request(struct bio *bio)
* yet.
*/
struct bio_list bio_list_on_stack[2];
blk_mq_req_flags_t flags = 0;
struct request_queue *q = bio->bi_disk->queue;
blk_qc_t ret = BLK_QC_T_NONE;
if (bio->bi_opf & REQ_NOWAIT)
flags = BLK_MQ_REQ_NOWAIT;
if (blk_queue_enter(q, flags) < 0) {
if (!blk_queue_dying(q) && (bio->bi_opf & REQ_NOWAIT))
bio_wouldblock_error(bio);
else
bio_io_error(bio);
return ret;
}
if (!generic_make_request_checks(bio))
goto out;
@ -2423,11 +2435,22 @@ blk_qc_t generic_make_request(struct bio *bio)
bio_list_init(&bio_list_on_stack[0]);
current->bio_list = bio_list_on_stack;
do {
struct request_queue *q = bio->bi_disk->queue;
blk_mq_req_flags_t flags = bio->bi_opf & REQ_NOWAIT ?
BLK_MQ_REQ_NOWAIT : 0;
bool enter_succeeded = true;
if (likely(blk_queue_enter(q, flags) == 0)) {
if (unlikely(q != bio->bi_disk->queue)) {
if (q)
blk_queue_exit(q);
q = bio->bi_disk->queue;
flags = 0;
if (bio->bi_opf & REQ_NOWAIT)
flags = BLK_MQ_REQ_NOWAIT;
if (blk_queue_enter(q, flags) < 0) {
enter_succeeded = false;
q = NULL;
}
}
if (enter_succeeded) {
struct bio_list lower, same;
/* Create a fresh bio_list for all subordinate requests */
@ -2435,8 +2458,6 @@ blk_qc_t generic_make_request(struct bio *bio)
bio_list_init(&bio_list_on_stack[0]);
ret = q->make_request_fn(q, bio);
blk_queue_exit(q);
/* sort new bios into those for a lower level
* and those for the same level
*/
@ -2463,6 +2484,8 @@ blk_qc_t generic_make_request(struct bio *bio)
current->bio_list = NULL; /* deactivate */
out:
if (q)
blk_queue_exit(q);
return ret;
}
EXPORT_SYMBOL(generic_make_request);