From ee0b0244030434cdda26777bfb98962447e080cd Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 25 Feb 2013 12:38:29 +1100 Subject: [PATCH] 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@vger.kernel.org (3.6.y 3.7.y 3.8.y) Reported-by: Tregaron Bayly Tested-by: Tregaron Bayly Signed-off-by: NeilBrown --- 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; -- 2.7.4