Hirokazu Takahashi 9b3c0a07e0 memcg: simplify force_empty and move_lists
As for force_empty, though this may not be the main topic here,
mem_cgroup_force_empty_list() can be implemented simpler.  It is possible to
make the function just call mem_cgroup_uncharge_page() instead of releasing
page_cgroups by itself.  The tip is to call get_page() before invoking
mem_cgroup_uncharge_page(), so the page won't be released during this
function.

Kamezawa-san points out that by the time mem_cgroup_uncharge_page() uncharges,
the page might have been reassigned to an lru of a different mem_cgroup, and
now be emptied from that; but Hugh claims that's okay, the end state is the
same as when it hasn't gone to another list.

And once force_empty stops taking lock_page_cgroup within mz->lru_lock,
mem_cgroup_move_lists() can be simplified to take mz->lru_lock directly while
holding page_cgroup lock (but still has to use try_lock_page_cgroup).

Signed-off-by: Hirokazu Takahashi <taka@valinux.co.jp>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-03-04 16:35:15 -08:00
..
2008-02-13 16:21:18 -08:00
2008-02-05 09:44:18 -08:00
2007-10-20 01:27:18 +02:00
2007-02-15 09:57:03 -08:00
2008-02-08 18:57:39 -08:00
2007-10-18 14:37:31 -07:00
2007-05-21 09:18:19 -07:00
2008-02-05 09:44:19 -08:00
2007-10-20 01:27:18 +02:00
2007-10-17 08:42:45 -07:00
2008-03-04 16:35:15 -08:00
2008-02-07 08:42:20 -08:00
2007-11-14 18:45:41 -08:00
2008-02-05 09:44:18 -08:00