From: Bart Van Assche bvanassche@acm.org
[ Upstream commit b3c6a59975415bde29cfd76ff1ab008edbf614a9 ]
Avoid that running test nvme/012 from the blktests suite triggers the following false positive lockdep complaint:
============================================ WARNING: possible recursive locking detected 5.0.0-rc3-xfstests-00015-g1236f7d60242 #841 Not tainted -------------------------------------------- ksoftirqd/1/16 is trying to acquire lock: 000000000282032e (&(&fq->mq_flush_lock)->rlock){..-.}, at: flush_end_io+0x4e/0x1d0
but task is already holding lock: 00000000cbadcbc2 (&(&fq->mq_flush_lock)->rlock){..-.}, at: flush_end_io+0x4e/0x1d0
other info that might help us debug this: Possible unsafe locking scenario:
CPU0 ---- lock(&(&fq->mq_flush_lock)->rlock); lock(&(&fq->mq_flush_lock)->rlock);
*** DEADLOCK ***
May be due to missing lock nesting notation
1 lock held by ksoftirqd/1/16: #0: 00000000cbadcbc2 (&(&fq->mq_flush_lock)->rlock){..-.}, at: flush_end_io+0x4e/0x1d0
stack backtrace: CPU: 1 PID: 16 Comm: ksoftirqd/1 Not tainted 5.0.0-rc3-xfstests-00015-g1236f7d60242 #841 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: dump_stack+0x67/0x90 __lock_acquire.cold.45+0x2b4/0x313 lock_acquire+0x98/0x160 _raw_spin_lock_irqsave+0x3b/0x80 flush_end_io+0x4e/0x1d0 blk_mq_complete_request+0x76/0x110 nvmet_req_complete+0x15/0x110 [nvmet] nvmet_bio_done+0x27/0x50 [nvmet] blk_update_request+0xd7/0x2d0 blk_mq_end_request+0x1a/0x100 blk_flush_complete_seq+0xe5/0x350 flush_end_io+0x12f/0x1d0 blk_done_softirq+0x9f/0xd0 __do_softirq+0xca/0x440 run_ksoftirqd+0x24/0x50 smpboot_thread_fn+0x113/0x1e0 kthread+0x121/0x140 ret_from_fork+0x3a/0x50
Cc: Christoph Hellwig hch@infradead.org Cc: Ming Lei ming.lei@redhat.com Cc: Hannes Reinecke hare@suse.com Signed-off-by: Bart Van Assche bvanassche@acm.org Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- block/blk-flush.c | 5 +++++ block/blk.h | 1 + 2 files changed, 6 insertions(+)
diff --git a/block/blk-flush.c b/block/blk-flush.c index 1eec9cbe5a0a..b1f0a1ac505c 100644 --- a/block/blk-flush.c +++ b/block/blk-flush.c @@ -69,6 +69,7 @@ #include <linux/blkdev.h> #include <linux/gfp.h> #include <linux/blk-mq.h> +#include <linux/lockdep.h>
#include "blk.h" #include "blk-mq.h" @@ -492,6 +493,9 @@ struct blk_flush_queue *blk_alloc_flush_queue(struct request_queue *q, INIT_LIST_HEAD(&fq->flush_queue[1]); INIT_LIST_HEAD(&fq->flush_data_in_flight);
+ lockdep_register_key(&fq->key); + lockdep_set_class(&fq->mq_flush_lock, &fq->key); + return fq;
fail_rq: @@ -506,6 +510,7 @@ void blk_free_flush_queue(struct blk_flush_queue *fq) if (!fq) return;
+ lockdep_unregister_key(&fq->key); kfree(fq->flush_rq); kfree(fq); } diff --git a/block/blk.h b/block/blk.h index 47fba9362e60..ffea1691470e 100644 --- a/block/blk.h +++ b/block/blk.h @@ -30,6 +30,7 @@ struct blk_flush_queue { * at the same time */ struct request *orig_rq; + struct lock_class_key key; spinlock_t mq_flush_lock; };