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From:   Xunlei Pang <xlpang@linux.alibaba.com>
To:     Michal Hocko <mhocko@suse.com>, Roman Gushchin <guro@fb.com>,
        Johannes Weiner <hannes@cmpxchg.org>
Cc:     linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH 1/3] mm/memcg: Fix min/low usage in propagate_protected_usage()
Date:   Mon,  3 Dec 2018 16:01:17 +0800
Message-Id: <20181203080119.18989-1-xlpang@linux.alibaba.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

When usage exceeds min, min usage should be min other than 0.
Apply the same for low.

Signed-off-by: Xunlei Pang <xlpang@linux.alibaba.com>
---
 mm/page_counter.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/mm/page_counter.c b/mm/page_counter.c
index de31470655f6..75d53f15f040 100644
--- a/mm/page_counter.c
+++ b/mm/page_counter.c
@@ -23,11 +23,7 @@ static void propagate_protected_usage(struct page_counter *c,
 		return;
 
 	if (c->min || atomic_long_read(&c->min_usage)) {
-		if (usage <= c->min)
-			protected = usage;
-		else
-			protected = 0;
-
+		protected = min(usage, c->min);
 		old_protected = atomic_long_xchg(&c->min_usage, protected);
 		delta = protected - old_protected;
 		if (delta)
@@ -35,11 +31,7 @@ static void propagate_protected_usage(struct page_counter *c,
 	}
 
 	if (c->low || atomic_long_read(&c->low_usage)) {
-		if (usage <= c->low)
-			protected = usage;
-		else
-			protected = 0;
-
+		protected = min(usage, c->low);
 		old_protected = atomic_long_xchg(&c->low_usage, protected);
 		delta = protected - old_protected;
 		if (delta)
-- 
2.13.5 (Apple Git-94)