linux-kernel - [patch -v4 6/8] memcg, vmscan: Do not attempt soft limit reclaim if it would not scan anything

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1370254735-13012-7-git-send-email-mhocko@suse.cz>
Date:	Mon,  3 Jun 2013 12:18:53 +0200
From:	Michal Hocko <mhocko@...e.cz>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Johannes Weiner <hannes@...xchg.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	linux-mm@...ck.org, cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org, Ying Han <yinghan@...gle.com>,
	Hugh Dickins <hughd@...gle.com>,
	Glauber Costa <glommer@...allels.com>,
	Michel Lespinasse <walken@...gle.com>,
	Greg Thelen <gthelen@...gle.com>, Tejun Heo <tj@...nel.org>,
	Balbir Singh <bsingharora@...il.com>
Subject: [patch -v4 6/8] memcg, vmscan: Do not attempt soft limit reclaim if it would not scan anything

mem_cgroup_should_soft_reclaim controls whether soft reclaim pass is
done and it always says yes currently. Memcg iterators are clever to
skip nodes that are not soft reclaimable quite efficiently but
mem_cgroup_should_soft_reclaim can be more clever and do not start the
soft reclaim pass at all if it knows that nothing would be scanned
anyway.

In order to do that, simply reuse mem_cgroup_soft_reclaim_eligible for
the target group of the reclaim and allow the pass only if the whole
subtree wouldn't be skipped.

Changes since v1
- do not export mem_cgroup_root and teach mem_cgroup_soft_reclaim_eligible
  to handle NULL memcg as mem_cgroup_root

Signed-off-by: Michal Hocko <mhocko@...e.cz>
---
 mm/memcontrol.c |    6 +++++-
 mm/vmscan.c     |    4 +++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 90495d5..8ff9366 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1941,7 +1941,11 @@ enum mem_cgroup_filter_t
 mem_cgroup_soft_reclaim_eligible(struct mem_cgroup *memcg,
 		struct mem_cgroup *root)
 {
-	struct mem_cgroup *parent = memcg;
+	struct mem_cgroup *parent;
+
+	if (!memcg)
+		memcg = root_mem_cgroup;
+	parent = memcg;
 
 	if (res_counter_soft_limit_excess(&memcg->res))
 		return VISIT;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 10bcbc2..dc78f07 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -142,7 +142,9 @@ static bool global_reclaim(struct scan_control *sc)
 
 static bool mem_cgroup_should_soft_reclaim(struct scan_control *sc)
 {
-	return !mem_cgroup_disabled();
+	struct mem_cgroup *root = sc->target_mem_cgroup;
+	return !mem_cgroup_disabled() &&
+		mem_cgroup_soft_reclaim_eligible(root, root) != SKIP_TREE;
 }
 #else
 static bool global_reclaim(struct scan_control *sc)
-- 
1.7.10.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/