On Sun, 2018-04-08 at 12:21 +0800, Ming Lei wrote:
> The following kernel oops is triggered by 'removing scsi device' during
> heavy IO.
Is the below patch sufficient to fix this?
Thanks,
Bart.
Subject: 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 check earlier in generic_make_request()
whether the queue has been marked as "dying".
---
block/blk-core.c | 72 +++++++++++++++++++++++++++++---------------------------
1 file changed, 37 insertions(+), 35 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index aa8c99fae527..3ac9dd25e04e 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2385,10 +2385,21 @@ blk_qc_t generic_make_request(struct bio *bio)
* yet.
*/
struct bio_list bio_list_on_stack[2];
+ blk_mq_req_flags_t flags = bio->bi_opf & REQ_NOWAIT ?
+ BLK_MQ_REQ_NOWAIT : 0;
+ struct request_queue *q = bio->bi_disk->queue;
blk_qc_t ret = BLK_QC_T_NONE;
if (!generic_make_request_checks(bio))
- goto out;
+ return ret;
+
+ if (blk_queue_enter(q, flags) < 0) {
+ if (unlikely(!blk_queue_dying(q) && (bio->bi_opf & REQ_NOWAIT)))
+ bio_wouldblock_error(bio);
+ else
+ bio_io_error(bio);
+ return ret;
+ }
/*
* We only want one ->make_request_fn to be active at a time, else
@@ -2423,46 +2434,37 @@ 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;
-
- if (likely(blk_queue_enter(q, flags) == 0)) {
- struct bio_list lower, same;
-
- /* Create a fresh bio_list for all subordinate requests
*/
- bio_list_on_stack[1] = bio_list_on_stack[0];
- 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
- */
- bio_list_init(&lower);
- bio_list_init(&same);
- while ((bio = bio_list_pop(&bio_list_on_stack[0])) !=
NULL)
- if (q == bio->bi_disk->queue)
- bio_list_add(&same, bio);
- else
- bio_list_add(&lower, bio);
- /* now assemble so we handle the lowest level first */
- bio_list_merge(&bio_list_on_stack[0], &lower);
- bio_list_merge(&bio_list_on_stack[0], &same);
- bio_list_merge(&bio_list_on_stack[0],
&bio_list_on_stack[1]);
- } else {
- if (unlikely(!blk_queue_dying(q) &&
- (bio->bi_opf & REQ_NOWAIT)))
- bio_wouldblock_error(bio);
+ struct bio_list lower, same;
+
+ WARN_ON_ONCE(!(flags & BLK_MQ_REQ_NOWAIT) &&
+ (bio->bi_opf & REQ_NOWAIT));
+ WARN_ON_ONCE(q != bio->bi_disk->queue);
+ q = bio->bi_disk->queue;
+ /* Create a fresh bio_list for all subordinate requests */
+ bio_list_on_stack[1] = bio_list_on_stack[0];
+ bio_list_init(&bio_list_on_stack[0]);
+ ret = q->make_request_fn(q, bio);
+
+ /* sort new bios into those for a lower level
+ * and those for the same level
+ */
+ bio_list_init(&lower);
+ bio_list_init(&same);
+ while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL)
+ if (q == bio->bi_disk->queue)
+ bio_list_add(&same, bio);
else
- bio_io_error(bio);
- }
+ bio_list_add(&lower, bio);
+ /* now assemble so we handle the lowest level first */
+ bio_list_merge(&bio_list_on_stack[0], &lower);
+ bio_list_merge(&bio_list_on_stack[0], &same);
+ bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]);
bio = bio_list_pop(&bio_list_on_stack[0]);
} while (bio);
current->bio_list = NULL; /* deactivate */
out:
+ blk_queue_exit(q);
return ret;
}
EXPORT_SYMBOL(generic_make_request);
--
2.16.2
