On Mon, 2018-04-09 at 14:54 +0800, Joseph Qi wrote:
> The oops happens during generic_make_request_checks(), in
> blk_throtl_bio() exactly.
> So if we want to bypass dying queue, we have to check this before
> generic_make_request_checks(), I think.
How about something like the patch below?
Thanks,
Bart.
Subject: [PATCH] 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 a blk_queue_enter() / blk_queue_exit() pair.
---
block/blk-core.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index d69888ff52f0..0c48bef8490f 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2388,9 +2388,24 @@ 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;
+ bool check_result;
blk_qc_t ret = BLK_QC_T_NONE;
- if (!generic_make_request_checks(bio))
+ 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;
+ }
+
+ check_result = generic_make_request_checks(bio);
+ blk_queue_exit(q);
+
+ if (!check_result)
goto out;
/*
--
2.16.2
