memcg: fix mem_cgroup_shrink_usage()

Current mem_cgroup_shrink_usage() has two problems.

1. It doesn't call mem_cgroup_out_of_memory and doesn't update
   last_oom_jiffies, so pagefault_out_of_memory invokes global OOM.

2. Considering hierarchy, shrinking has to be done from the
   mem_over_limit, not from the memcg which the page would be charged to.

mem_cgroup_try_charge_swapin() does all of these things properly, so we
use it and call cancel_charge_swapin when it succeeded.

The name of "shrink_usage" is not appropriate for this behavior, so we
change it too.

Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.cn>
Cc: Paul Menage <menage@google.com>
Cc: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index f9cb20ebb990..b25f95ce3db7 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1340,8 +1340,12 @@ repeat:
                         shmem_swp_unmap(entry);
                         spin_unlock(&info->lock);
                         if (error == -ENOMEM) {
-                                /* allow reclaim from this memory cgroup */
-                                error = mem_cgroup_shrink_usage(swappage,
+                                /*
+                                 * reclaim from proper memory cgroup and
+                                 * call memcg's OOM if needed.
+                                 */
+                                error = mem_cgroup_shmem_charge_fallback(
+                                                                swappage,
                                                                 current->mm,
                                                                 gfp);
                                 if (error) {