memcg: never OOM when charging huge pages

Huge page coverage should obviously have less priority than the continued
execution of a process.

Never kill a process when charging it a huge page fails.  Instead, give up
after the first failed reclaim attempt and fall back to regular pages.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: 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, 8 insertions, 2 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0e81eb5f0aea..fc75f34ba609 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2351,13 +2351,19 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
                                 gfp_t gfp_mask, enum charge_type ctype)
 {
         struct mem_cgroup *mem = NULL;
+        int page_size = PAGE_SIZE;
         struct page_cgroup *pc;
+        bool oom = true;
         int ret;
-        int page_size = PAGE_SIZE;
 
         if (PageTransHuge(page)) {
                 page_size <<= compound_order(page);
                 VM_BUG_ON(!PageTransHuge(page));
+                /*
+                 * Never OOM-kill a process for a huge page.  The
+                 * fault handler will fall back to regular pages.
+                 */
+                oom = false;
         }
 
         pc = lookup_page_cgroup(page);
@@ -2366,7 +2372,7 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
                 return 0;
         prefetchw(pc);
 
-        ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, true, page_size);
+        ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, oom, page_size);
         if (ret || !mem)
                 return ret;