From ba4666388f1a69487e0a64e3626564d37feef2c0 Mon Sep 17 00:00:00 2001
From: "T.kabe" <kabe@>
Date: Fri, 3 Mar 2017 14:29:26 +0900
Subject: [PATCH 1/4] get rid of propagate_umount() mistakenly treating slaves as busy.

[upstream commit 88b368f27a094277143d8ecd5a056116f6a41520]
Author: Al Viro <viro@zeniv.linux.org.uk>
Date:   Mon Aug 18 15:09:26 2014 -0400

    get rid of propagate_umount() mistakenly treating slaves as busy.

    The check in __propagate_umount() ("has somebody explicitly mounted
    something on that slave?") is done *before* taking the already doomed
    victims out of the child lists.

    Cc: stable@vger.kernel.org
    Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/namespace.c | 4 +++-
 fs/pnode.c     | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index 9440b6a..0053bfc 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1195,6 +1195,9 @@ void umount_tree(struct mount *mnt, int propagate)
 	for (p = mnt; p; p = next_mnt(p, mnt))
 		list_move(&p->mnt_hash, &tmp_list);
 
+	list_for_each_entry(p, &tmp_list, mnt_hash)
+		list_del_init(&p->mnt_child);
+
 	if (propagate)
 		propagate_umount(&tmp_list);
 
@@ -1203,7 +1206,6 @@ void umount_tree(struct mount *mnt, int propagate)
 		list_del_init(&p->mnt_list);
 		__touch_mnt_namespace(p->mnt_ns);
 		p->mnt_ns = NULL;
-		list_del_init(&p->mnt_child);
 		if (mnt_has_parent(p)) {
 			p->mnt_parent->mnt_ghosts++;
 			put_mountpoint(p->mnt_mp);
diff --git a/fs/pnode.c b/fs/pnode.c
index 54bd043..983cf93 100644
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -390,8 +390,10 @@ static void __propagate_umount(struct mount *mnt)
 		 * umount the child only if the child has no
 		 * other children
 		 */
-		if (child && list_empty(&child->mnt_mounts))
+		if (child && list_empty(&child->mnt_mounts)) {
+			list_del_init(&child->mnt_child);
 			list_move_tail(&child->mnt_hash, &mnt->mnt_hash);
+		}
 	}
 }
 
-- 
1.8.3.1