From 2344bec788b097b2d1198758bd29c583812b864e Mon Sep 17 00:00:00 2001
From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Thu, 31 May 2012 16:26:18 -0700
Subject: [PATCH] proc: use mm_access() instead of ptrace_may_access()

mm_access() handles this much better, and avoids some race conditions.

Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 fs/proc/base.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index cca635d252d4..155dee600ed4 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2022,11 +2022,8 @@ static int map_files_d_revalidate(struct dentry *dentry, struct nameidata *nd)
 	if (!task)
 		goto out_notask;
 
-	if (!ptrace_may_access(task, PTRACE_MODE_READ))
-		goto out;
-
-	mm = get_task_mm(task);
-	if (!mm)
+	mm = mm_access(task, PTRACE_MODE_READ);
+	if (IS_ERR_OR_NULL(mm))
 		goto out;
 
 	if (!dname_to_vma_addr(dentry, &vm_start, &vm_end)) {
-- 
2.34.1