tree e3ac7ca8cfe5ac02b0df83a4aef5f37e59d7d61f
parent c8dad2bb6307f5b00f804a686917105206a4d5c9
author KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> 1231380475 -0800
committer Linus Torvalds <torvalds@linux-foundation.org> 1231432264 -0800

memcg: new force_empty to free pages under group

By memcg-move-all-accounts-to-parent-at-rmdir.patch, there is no leak of
memory usage and force_empty is removed.

This patch adds "force_empty" again, in reasonable manner.

memory.force_empty file works when

  #echo 0 (or some) > memory.force_empty
  and have following function.

  1. only works when there are no task in this cgroup.
  2. free all page under this cgroup as much as possible.
  3. page which cannot be freed will be moved up to parent.
  4. Then, memcg will be empty after above echo returns.

This is much better behavior than old "force_empty" which just forget
all accounts. This patch also check signal_pending() and above "echo"
can be stopped by "Ctrl-C".

[akpm@linux-foundation.org: cleanup]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>