From cd4a4ae4683dc2e09380118e205e057896dcda2b Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Sat, 2 Jun 2018 14:04:07 -0600 Subject: block: don't use blocking queue entered for recursive bio submits If we end up splitting a bio and the queue goes away between the initial submission and the later split submission, then we can block forever in blk_queue_enter() waiting for the reference to drop to zero. This will never happen, since we already hold a reference. Mark a split bio as already having entered the queue, so we can just use the live non-blocking queue enter variant. Thanks to Tetsuo Handa for the analysis. Reported-by: syzbot+c4f9cebf9d651f6e54de@syzkaller.appspotmail.com Signed-off-by: Jens Axboe --- include/linux/blk_types.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux') diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index 4cb970cdcd11..3c4f390aea4b 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -229,6 +229,8 @@ struct bio { * throttling rules. Don't do it again. */ #define BIO_TRACE_COMPLETION 10 /* bio_endio() should trace the final completion * of this bio. */ +#define BIO_QUEUE_ENTERED 11 /* can use blk_queue_enter_live() */ + /* See BVEC_POOL_OFFSET below before adding new flags */ /* -- cgit