linux-kernel - [patch 2/9] mm: memcontrol: rearrange charging fast path

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: <1398889543-23671-3-git-send-email-hannes@cmpxchg.org>
Date:	Wed, 30 Apr 2014 16:25:36 -0400
From:	Johannes Weiner <hannes@...xchg.org>
To:	linux-mm@...ck.org
Cc:	Michal Hocko <mhocko@...e.cz>, Hugh Dickins <hughd@...gle.com>,
	Tejun Heo <tj@...nel.org>, cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [patch 2/9] mm: memcontrol: rearrange charging fast path

The charging path currently starts out with OOM condition checks when
OOM is the rarest possible case.

Rearrange this code to run OOM/task dying checks only after trying the
percpu charge and the res_counter charge and bail out before entering
reclaim.  Attempting a charge does not hurt an (oom-)killed task as
much as every charge attempt having to check OOM conditions.  Also,
only check __GFP_NOFAIL when the charge would actually fail.

Signed-off-by: Johannes Weiner <hannes@...xchg.org>
---
 mm/memcontrol.c | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 75dfeb8fa98b..6ce59146fec7 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2598,21 +2598,6 @@ static int mem_cgroup_try_charge(struct mem_cgroup *memcg,
 
 	if (mem_cgroup_is_root(memcg))
 		goto done;
-	/*
-	 * Unlike in global OOM situations, memcg is not in a physical
-	 * memory shortage.  Allow dying and OOM-killed tasks to
-	 * bypass the last charges so that they can exit quickly and
-	 * free their memory.
-	 */
-	if (unlikely(test_thread_flag(TIF_MEMDIE) ||
-		     fatal_signal_pending(current)))
-		goto bypass;
-
-	if (unlikely(task_in_memcg_oom(current)))
-		goto nomem;
-
-	if (gfp_mask & __GFP_NOFAIL)
-		oom = false;
 retry:
 	if (consume_stock(memcg, nr_pages))
 		goto done;
@@ -2634,6 +2619,19 @@ retry:
 		goto retry;
 	}
 
+	/*
+	 * Unlike in global OOM situations, memcg is not in a physical
+	 * memory shortage.  Allow dying and OOM-killed tasks to
+	 * bypass the last charges so that they can exit quickly and
+	 * free their memory.
+	 */
+	if (unlikely(test_thread_flag(TIF_MEMDIE) ||
+		     fatal_signal_pending(current)))
+		goto bypass;
+
+	if (unlikely(task_in_memcg_oom(current)))
+		goto nomem;
+
 	if (!(gfp_mask & __GFP_WAIT))
 		goto nomem;
 
@@ -2662,6 +2660,9 @@ retry:
 	if (mem_cgroup_wait_acct_move(mem_over_limit))
 		goto retry;
 
+	if (gfp_mask & __GFP_NOFAIL)
+		goto bypass;
+
 	if (fatal_signal_pending(current))
 		goto bypass;
 
-- 
1.9.2

--
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/