Could you please try this patch?
From 271f5a9b8f8ae0db95de72779d115c9d0b9d3cc5 Mon Sep 17 00:00:00 2001
From: NeilBrown <email@example.com>
Date: Mon, 1 Sep 2008 12:32:52 +1000
Subject: [PATCH] Remove invalidate_partition call from do_md_stop.
When stopping an md array, or just switching to read-only, we
currently call invalidate_partition while holding the mddev lock.
The main reason for this is probably to ensure all dirty buffers
are flushed (invalidate_partition calls fsync_bdev).
However if any dirty buffers are found, it will almost certainly cause
a deadlock as starting writeout will require an update to the
superblock, and performing that updates requires taking the mddev
lock - which is already held.
This deadlock can be demonstrated by running "reboot -f -n" with
a root filesystem on md/raid, and some dirty buffers in memory.
All other calls to stop an array should already happen after a flush.
The normal sequence is to stop using the array (e.g. umount) which
will cause __blkdev_put to call sync_blockdev. Then open the
array and issue the STOP_ARRAY ioctl while the buffers are all still
So this invalidate_partition is normally a no-op, except for one case
where it will cause a deadlock.
So remove it.
This patch possibly addresses the regression recored in
though it isn't yet clear how it ever worked.
Signed-off-by: NeilBrown <firstname.lastname@example.org>
drivers/md/md.c | 2 --
1 files changed, 0 insertions(+), 2 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 8cfadc5..4790c83 100644
@@ -3841,8 +3841,6 @@ static int do_md_stop(mddev_t * mddev, int mode, int is_open)
- invalidate_partition(disk, 0);
case 1: /* readonly */
err = -ENXIO;