[Devel] [PATCH RHEL7 COMMIT] memcg: fix __GFP_NORETRY check

[Vladimir Davydov]

The commit is pushed to "branch-rh7-3.10.0-229.7.2-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-229.7.2.vz7.6.8
------>
commit 33087f4cfe0d5048018f11af4d0ae1ebefb90ff3
Author: Vladimir Davydov <vdavydov at parallels.com>
Date:   Tue Sep 8 19:30:59 2015 +0400

    memcg: fix __GFP_NORETRY check
    
    When backporting mainstream commit 28c34c291e74 I misplaced the
    __GFP_NORETRY check by mistake: if this flag is passed we should give up
    after the first unsuccessful reclaim attempt, while I placed the check
    so that we can retry reclaim many times. Fix that.
    
    Fixes: 8aee40dd982b ("ms/mm: memcontrol: reclaim at least once for __GFP_NORETRY")
    Signed-off-by: Vladimir Davydov <vdavydov at parallels.com>
---
 mm/memcontrol.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0cb329028a29..6a0751f878d3 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2768,6 +2768,11 @@ static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
 	ret = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags);
 	if (mem_cgroup_margin(mem_over_limit) >= nr_pages)
 		return CHARGE_RETRY;
+
+	if (gfp_mask & __GFP_NORETRY) {
+		mem_cgroup_inc_failcnt(mem_over_limit, gfp_mask, nr_pages);
+		return CHARGE_WOULDBLOCK;
+	}
 	/*
 	 * Even though the limit is exceeded at this point, reclaim
 	 * may have been able to free some pages.  Retry the charge
@@ -2793,9 +2798,6 @@ static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
 
 	mem_cgroup_inc_failcnt(mem_over_limit, gfp_mask, nr_pages);
 
-	if (gfp_mask & __GFP_NORETRY)
-		return CHARGE_NOMEM;
-
 	/* check OOM */
 	if (!mem_cgroup_handle_oom(mem_over_limit, gfp_mask, get_order(csize)))
 		return CHARGE_OOM_DIE;