This is a note to let you know that I've just added the patch titled
Revert "md/raid5: Wait for MD_SB_CHANGE_PENDING in raid5d"
to the 4.19-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:
revert-md-raid5-wait-for-md_sb_change_pending-in-rai.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit a15058db27bdbfa458bd1e886eac683d5d1babfe
Author: Junxiao Bi <junxiao.bi@xxxxxxxxxx>
Date: Wed Nov 8 10:22:16 2023 -0800
Revert "md/raid5: Wait for MD_SB_CHANGE_PENDING in raid5d"
[ Upstream commit bed9e27baf52a09b7ba2a3714f1e24e17ced386d ]
This reverts commit 5e2cf333b7bd5d3e62595a44d598a254c697cd74.
That commit introduced the following race and can cause system hung.
md_write_start: raid5d:
// mddev->in_sync == 1
set "MD_SB_CHANGE_PENDING"
// running before md_write_start wakeup it
waiting "MD_SB_CHANGE_PENDING" cleared
>>>>>>>>> hung
wakeup mddev->thread
...
waiting "MD_SB_CHANGE_PENDING" cleared
>>>> hung, raid5d should clear this flag
but get hung by same flag.
The issue reverted commit fixing is fixed by last patch in a new way.
Fixes: 5e2cf333b7bd ("md/raid5: Wait for MD_SB_CHANGE_PENDING in raid5d")
Cc: stable@xxxxxxxxxxxxxxx # v5.19+
Signed-off-by: Junxiao Bi <junxiao.bi@xxxxxxxxxx>
Reviewed-by: Yu Kuai <yukuai3@xxxxxxxxxx>
Signed-off-by: Song Liu <song@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20231108182216.73611-2-junxiao.bi@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index b98abe927d06..e2fcc09a18cd 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -44,7 +44,6 @@
*/
#include <linux/blkdev.h>
-#include <linux/delay.h>
#include <linux/kthread.h>
#include <linux/raid/pq.h>
#include <linux/async_tx.h>
@@ -6330,18 +6329,7 @@ static void raid5d(struct md_thread *thread)
spin_unlock_irq(&conf->device_lock);
md_check_recovery(mddev);
spin_lock_irq(&conf->device_lock);
-
- /*
- * Waiting on MD_SB_CHANGE_PENDING below may deadlock
- * seeing md_check_recovery() is needed to clear
- * the flag when using mdmon.
- */
- continue;
}
-
- wait_event_lock_irq(mddev->sb_wait,
- !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags),
- conf->device_lock);
}
pr_debug("%d stripes handled\n", handled);
