Commit 3af33516 authored Sep 12, 2013 by Sha Zhengju Committed by Linus Torvalds Sep 12, 2013

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>

parent 6de5a8bf

kernel/res_counter.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -195,6 +195,10 @@ int res_counter_memparse_write_strategy(const char *buf,
		if (*end != '\0')
		return -EINVAL;

		if (PAGE_ALIGN(res) >= res)
		res = PAGE_ALIGN(res);
		else
		*res = RES_COUNTER_MAX;

		return 0;
		}

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