From: Kautuk Consul <consul.kautuk@gmail.com>
Date: Tue, 1 Nov 2011 00:09:11 +0000 (-0700)
Subject: vmscan.c: fix invalid strict_strtoul() check in write_scan_unevictable_node()
X-Git-Tag: Ubuntu-5.2.0-15.16~19440^2~72
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=3f380998aeb51b99d5d22cadb41162e1e9db70d2;p=mirror_ubuntu-eoan-kernel.git

vmscan.c: fix invalid strict_strtoul() check in write_scan_unevictable_node()

write_scan_unevictable_node() checks the value req returned by
strict_strtoul() and returns 1 if req is 0.

However, when strict_strtoul() returns 0, it means successful conversion
of buf to unsigned long.

Due to this, the function was not proceeding to scan the zones for
unevictable pages even though we write a valid value to the
scan_unevictable_pages sys file.

Change this check slightly to check for invalid value in buf as well as 0
value stored in res after successful conversion via strict_strtoul.  In
both cases, we do not perform the scanning of this node's zones.

Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 51bc4bf3f723..ac644fe85589 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3520,8 +3520,8 @@ static ssize_t write_scan_unevictable_node(struct sys_device *dev,
 	unsigned long res;
 	unsigned long req = strict_strtoul(buf, 10, &res);
 
-	if (!req)
-		return 1;	/* zero is no-op */
+	if (req || !res)
+		return 1; /* Invalid input or zero is no-op */
 
 	for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
 		if (!populated_zone(zone))