memcg: fix oom kill behavior

In current page-fault code,

	handle_mm_fault()
		-> ...
		-> mem_cgroup_charge()
		-> map page or handle error.
	-> check return code.

If page fault's return code is VM_FAULT_OOM, page_fault_out_of_memory() is
called.  But if it's caused by memcg, OOM should have been already
invoked.

Then, I added a patch: a636b327f731143ccc544b966cfd8de6cb6d72c6.  That
patch records last_oom_jiffies for memcg's sub-hierarchy and prevents
page_fault_out_of_memory from being invoked in near future.

But Nishimura-san reported that check by jiffies is not enough when the
system is terribly heavy.

This patch changes memcg's oom logic as.
 * If memcg causes OOM-kill, continue to retry.
 * remove jiffies check which is used now.
 * add memcg-oom-lock which works like perzone oom lock.
 * If current is killed(as a process), bypass charge.

Something more sophisticated can be added but this pactch does
fundamental things.
TODO:
 - add oom notifier
 - add permemcg disable-oom-kill flag and freezer at oom.
 - more chances for wake up oom waiter (when changing memory limit etc..)

Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Tested-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 6 deletions

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 1f9b119f4ace..44301c6affa8 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -124,7 +124,6 @@ static inline bool mem_cgroup_disabled(void)
         return false;
 }
 
-extern bool mem_cgroup_oom_called(struct task_struct *task);
 void mem_cgroup_update_file_mapped(struct page *page, int val);
 unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order,
                                                 gfp_t gfp_mask, int nid,
@@ -258,11 +257,6 @@ static inline bool mem_cgroup_disabled(void)
         return true;
 }
 
-static inline bool mem_cgroup_oom_called(struct task_struct *task)
-{
-        return false;
-}
-
 static inline int
 mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg)
 {