From: Yu Kuai <yukuai3@xxxxxxxxxx>
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@xxxxxxxxxxxxxxx>
Closes: https://lore.kernel.org/lkml/20240130172524.0000417b@xxxxxxxxxxxxxxx/
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
drivers/md/md.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
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)
--
2.39.2
