From: Andrew Morton <akpm@linux-foundation.org>

mm-only debug patch...

Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/attr.c |    2 ++
 1 file changed, 2 insertions(+)

diff -puN fs/attr.c~notify_change-callers-must-hold-i_mutex fs/attr.c
--- a/fs/attr.c~notify_change-callers-must-hold-i_mutex
+++ a/fs/attr.c
@@ -108,6 +108,8 @@ int notify_change(struct dentry * dentry
 	struct timespec now;
 	unsigned int ia_valid = attr->ia_valid;
 
+	WARN_ON_ONCE(!mutex_is_locked(&inode->i_mutex));
+
 	now = current_fs_time(inode->i_sb);
 
 	attr->ia_ctime = now;
_