From 3af3351676c3deecfd632f47719fb0d13a061ba8 Mon Sep 17 00:00:00 2001
From: Sha Zhengju <handai.szj@taobao.com>
Date: Thu, 12 Sep 2013 15:13:48 -0700
Subject: [PATCH] memcg: avoid overflow caused by PAGE_ALIGN

Since PAGE_ALIGN is aligning up(the next page boundary), so after
PAGE_ALIGN, the value might be overflow, such as write the MAX value to
*.limit_in_bytes.

  $ cat /cgroup/memory/memory.limit_in_bytes
  18446744073709551615

  # echo 18446744073709551615 > /cgroup/memory/memory.limit_in_bytes
  bash: echo: write error: Invalid argument

Some user programs might depend on such behaviours(like libcg, we read
the value in snapshot, then use the value to reset cgroup later), and
that will cause confusion.  So we need to fix it.

Signed-off-by: Sha Zhengju <handai.szj@taobao.com>
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Jeff Liu <jeff.liu@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 kernel/res_counter.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/res_counter.c b/kernel/res_counter.c
index 3f0417f97e76..085d3ae478fe 100644
--- a/kernel/res_counter.c
+++ b/kernel/res_counter.c
@@ -195,6 +195,10 @@ int res_counter_memparse_write_strategy(const char *buf,
 	if (*end != '\0')
 		return -EINVAL;
 
-	*res = PAGE_ALIGN(*res);
+	if (PAGE_ALIGN(*res) >= *res)
+		*res = PAGE_ALIGN(*res);
+	else
+		*res = RES_COUNTER_MAX;
+
 	return 0;
 }
-- 
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