commit: ee0b0244030434cdda26777bfb98962447e080cd
From: NeilBrown <neilb@xxxxxxx>
Date: Mon, 25 Feb 2013 12:38:29 +1100
Subject: md/raid1,raid10: fix deadlock with freeze_array()
When raid1/raid10 needs to fix a read error, it first drains
all pending requests by calling freeze_array().
This calls flush_pending_writes() if it needs to sleep,
but some writes may be pending in a per-process plug rather
than in the per-array request queue.
When raid1{,0}_unplug() moves the request from the per-process
plug to the per-array request queue (from which
flush_pending_writes() can flush them), it needs to wake up
freeze_array(), or freeze_array() will never flush them and so
it will block forever.
So add the requires wake_up() calls.
This bug was introduced by commit
f54a9d0e59c4bea3db733921ca9147612a6f292c
for raid1 and a similar commit for RAID10, and so has been present
since linux-3.6. As the bug causes a deadlock I believe this fix is
suitable for -stable.
Cc: stable@xxxxxxxxxxxxxxx (3.6.y 3.7.y 3.8.y)
Reported-by: Tregaron Bayly <tbayly@xxxxxxxxxxxx>
Tested-by: Tregaron Bayly <tbayly@xxxxxxxxxxxx>
Signed-off-by: NeilBrown <neilb@xxxxxxx>
---
drivers/md/raid1.c | 1 +
drivers/md/raid10.c | 1 +
2 files changed, 2 insertions(+)
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 6e5d5a5..fd86b37 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -967,6 +967,7 @@ static void raid1_unplug(struct blk_plug_cb *cb, bool from_schedule)
bio_list_merge(&conf->pending_bio_list, &plug->pending);
conf->pending_count += plug->pending_cnt;
spin_unlock_irq(&conf->device_lock);
+ wake_up(&conf->wait_barrier);
md_wakeup_thread(mddev->thread);
kfree(plug);
return;
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 61ed150..77b562d 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1119,6 +1119,7 @@ static void raid10_unplug(struct blk_plug_cb *cb, bool from_schedule)
bio_list_merge(&conf->pending_bio_list, &plug->pending);
conf->pending_count += plug->pending_cnt;
spin_unlock_irq(&conf->device_lock);
+ wake_up(&conf->wait_barrier);
md_wakeup_thread(mddev->thread);
kfree(plug);
return;
--
1.7.10.4
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