| Message ID | 20191218002435.48863-1-bvanassche@acm.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block: Fix a lockdep complaint triggered by request queue flushing | expand |
On 12/17/19 5:24 PM, Bart Van Assche wrote: > 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 Applied, thanks.
diff --git a/block/blk-flush.c b/block/blk-flush.c index 1777346baf06..3f977c517960 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" @@ -505,6 +506,9 @@ 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: @@ -519,6 +523,7 @@ 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 6842f28c033e..0b8884353f6b 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; };
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> --- block/blk-flush.c | 5 +++++ block/blk.h | 1 + 2 files changed, 6 insertions(+)