This is a note to let you know that I've just added the patch titled
md/raid5: Fix livelock when array is both resyncing and degraded.
to the 3.19-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-raid5-fix-livelock-when-array-is-both-resyncing-and-degraded.patch
and it can be found in the queue-3.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 26ac107378c4742978216be1005b7291b799c7b2 Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@xxxxxxx>
Date: Wed, 18 Feb 2015 11:35:14 +1100
Subject: md/raid5: Fix livelock when array is both resyncing and degraded.
From: NeilBrown <neilb@xxxxxxx>
commit 26ac107378c4742978216be1005b7291b799c7b2 upstream.
Commit a7854487cd7128a30a7f4f5259de9f67d5efb95f:
md: When RAID5 is dirty, force reconstruct-write instead of read-modify-write.
Causes an RCW cycle to be forced even when the array is degraded.
A degraded array cannot support RCW as that requires reading all data
blocks, and one may be missing.
Forcing an RCW when it is not possible causes a live-lock and the code
spins, repeatedly deciding to do something that cannot succeed.
So change the condition to only force RCW on non-degraded arrays.
Reported-by: Manibalan P <pmanibalan@xxxxxxxxxxxxxx>
Bisected-by: Jes Sorensen <Jes.Sorensen@xxxxxxxxxx>
Tested-by: Jes Sorensen <Jes.Sorensen@xxxxxxxxxx>
Signed-off-by: NeilBrown <neilb@xxxxxxx>
Fixes: a7854487cd7128a30a7f4f5259de9f67d5efb95f
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/raid5.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3102,7 +3102,8 @@ static void handle_stripe_dirtying(struc
* generate correct data from the parity.
*/
if (conf->max_degraded == 2 ||
- (recovery_cp < MaxSector && sh->sector >= recovery_cp)) {
+ (recovery_cp < MaxSector && sh->sector >= recovery_cp &&
+ s->failed == 0)) {
/* Calculate the real rcw later - for now make it
* look like rcw is cheaper
*/
Patches currently in stable-queue which might be from neilb@xxxxxxx are
queue-3.19/md-raid5-fix-livelock-when-array-is-both-resyncing-and-degraded.patch
queue-3.19/md-raid1-fix-read-balance-when-a-drive-is-write-mostly.patch
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