From 71879d3cb3dd8f2dfdefb252775c1b3ea04a3dd4 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@redhat.com>
Date: Tue, 31 Jan 2012 17:14:38 +0100
Subject: proc: mem_release() should check mm != NULL

mem_release() can hit mm == NULL, add the necessary check.

Cc: stable@kernel.org
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 9cde9edf..c3617ea 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -822,8 +822,8 @@ loff_t mem_lseek(struct file *file, loff_t offset, int orig)
 static int mem_release(struct inode *inode, struct file *file)
 {
 	struct mm_struct *mm = file->private_data;
-
-	mmput(mm);
+	if (mm)
+		mmput(mm);
 	return 0;
 }
 
-- 
cgit v0.10.2