diff mbox series

[v5,06/14] md: fix missing release of 'active_io' for flush

Message ID 20240201092559.910982-7-yukuai1@huaweicloud.com
State New
Headers
Series [v5,01/14] md: don't ignore suspended array in md_check_recovery() |

Commit Message

Yu Kuai Feb. 1, 2024, 9:25 a.m. UTC 
  From: Yu Kuai <yukuai3@huawei.com>

submit_flushes
 atomic_set(&mddev->flush_pending, 1);
 rdev_for_each_rcu(rdev, mddev)
  atomic_inc(&mddev->flush_pending);
  bi->bi_end_io = md_end_flush
  submit_bio(bi);
                        /* flush io is done first */
                        md_end_flush
                         if (atomic_dec_and_test(&mddev->flush_pending))
                          percpu_ref_put(&mddev->active_io)
                          -> active_io is not released

 if (atomic_dec_and_test(&mddev->flush_pending))
  -> missing release of active_io

For consequence, mddev_suspend() will wait for 'active_io' to be zero
forever.

Fix this problem by releasing 'active_io' in submit_flushes() if
'flush_pending' is decreased to zero.

Fixes: fa2bbff7b0b4 ("md: synchronize flush io with array reconfiguration")
Reported-by: Blazej Kucman <blazej.kucman@linux.intel.com>
Closes: https://lore.kernel.org/lkml/20240130172524.0000417b@linux.intel.com/
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
 drivers/md/md.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Comments

Song Liu Feb. 8, 2024, 7:47 a.m. UTC | #1 
On Thu, Feb 1, 2024 at 1:30 AM Yu Kuai <yukuai1@huaweicloud.com> wrote:
>
> From: Yu Kuai <yukuai3@huawei.com>
>
> submit_flushes
>  atomic_set(&mddev->flush_pending, 1);
>  rdev_for_each_rcu(rdev, mddev)
>   atomic_inc(&mddev->flush_pending);
>   bi->bi_end_io = md_end_flush
>   submit_bio(bi);
>                         /* flush io is done first */
>                         md_end_flush
>                          if (atomic_dec_and_test(&mddev->flush_pending))
>                           percpu_ref_put(&mddev->active_io)
>                           -> active_io is not released
>
>  if (atomic_dec_and_test(&mddev->flush_pending))
>   -> missing release of active_io
>
> For consequence, mddev_suspend() will wait for 'active_io' to be zero
> forever.
>
> Fix this problem by releasing 'active_io' in submit_flushes() if
> 'flush_pending' is decreased to zero.
>
> Fixes: fa2bbff7b0b4 ("md: synchronize flush io with array reconfiguration")
> Reported-by: Blazej Kucman <blazej.kucman@linux.intel.com>
> Closes: https://lore.kernel.org/lkml/20240130172524.0000417b@linux.intel.com/
> Signed-off-by: Yu Kuai <yukuai3@huawei.com>

Applied this patch to md-6.8.

Thanks,
Song
diff mbox series

Patch

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 85fde05c37dd..9e41a9aaba8b 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -579,8 +579,12 @@  static void submit_flushes(struct work_struct *ws)
 			rcu_read_lock();
 		}
 	rcu_read_unlock();
-	if (atomic_dec_and_test(&mddev->flush_pending))
+	if (atomic_dec_and_test(&mddev->flush_pending)) {
+		/* The pair is percpu_ref_get() from md_flush_request() */
+		percpu_ref_put(&mddev->active_io);
+
 		queue_work(md_wq, &mddev->flush_work);
+	}
 }
 
 static void md_submit_flush_data(struct work_struct *ws)