This is a note to let you know that I've just added the patch titled
md/raid1,raid10: fix deadlock with freeze_array()
to the 3.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
md-raid1-raid10-fix-deadlock-with-freeze_array.patch
and it can be found in the queue-3.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ee0b0244030434cdda26777bfb98962447e080cd Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@xxxxxxx>
Date: Mon, 25 Feb 2013 12:38:29 +1100
Subject: md/raid1,raid10: fix deadlock with freeze_array()
From: NeilBrown <neilb@xxxxxxx>
commit ee0b0244030434cdda26777bfb98962447e080cd upstream.
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.
Reported-by: Tregaron Bayly <tbayly@xxxxxxxxxxxx>
Tested-by: Tregaron Bayly <tbayly@xxxxxxxxxxxx>
Signed-off-by: NeilBrown <neilb@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/raid1.c | 1 +
drivers/md/raid10.c | 1 +
2 files changed, 2 insertions(+)
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -967,6 +967,7 @@ static void raid1_unplug(struct blk_plug
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;
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1073,6 +1073,7 @@ static void raid10_unplug(struct blk_plu
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;
Patches currently in stable-queue which might be from neilb@xxxxxxx are
queue-3.8/md-raid1-raid10-fix-deadlock-with-freeze_array.patch
queue-3.8/md-fix-two-bugs-when-attempting-to-resize-raid0-array.patch
queue-3.8/md-raid0-fix-error-return-from-create_stripe_zones.patch
queue-3.8/md-protect-against-crash-upon-fsync-on-ro-array.patch
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