Patch "md: fix deadlock error in recent patch." has been added to the 4.14-stable tree

Patch "md: fix deadlock error in recent patch." has been added to the 4.14-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    md: fix deadlock error in recent patch.

to the 4.14-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-fix-deadlock-error-in-recent-patch.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From d47c8ad261f787af22a220ffcc2d07afba809223 Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@suse.com>
Date: Thu, 5 Oct 2017 16:23:16 +1100
Subject: md: fix deadlock error in recent patch.

From: NeilBrown <neilb@suse.com>

commit d47c8ad261f787af22a220ffcc2d07afba809223 upstream.

A recent patch aimed to cause md_write_start() to fail (rather than
block) when the mddev was suspending, so as to avoid deadlocks.
Unfortunately the test in wait_event() was wrong, and it didn't change
behaviour at all.

We wait_event() must wait until the metadata is written OR the array is
suspending.

Fixes: cc27b0c78c79 ("md: fix deadlock between mddev_suspend() and md_write_start()")
Reported-by: Xiao Ni <xni@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/md/md.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -8039,7 +8039,8 @@ bool md_write_start(struct mddev *mddev,
 	if (did_change)
 		sysfs_notify_dirent_safe(mddev->sysfs_state);
 	wait_event(mddev->sb_wait,
-		   !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags) && !mddev->suspended);
+		   !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags) ||
+		   mddev->suspended);
 	if (test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)) {
 		percpu_ref_put(&mddev->writes_pending);
 		return false;


Patches currently in stable-queue which might be from neilb@suse.com are

queue-4.14/md-fix-deadlock-error-in-recent-patch.patch
queue-4.14/autofs-don-t-fail-mount-for-transient-error.patch
queue-4.14/md-bitmap-revert-a-patch.patch
queue-4.14/nfs-revalidate-.-etc-correctly-on-open.patch