linux-kernel - [PATCH] mm: memcontrol: avoid unused function warning

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Message-Id: <20160824082301.632345-1-arnd@arndb.de>
Date:   Wed, 24 Aug 2016 10:22:43 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Vladimir Davydov <vdavydov@...tuozzo.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Tejun Heo <tj@...nel.org>,
        Mel Gorman <mgorman@...hsingularity.net>,
        cgroups@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] mm: memcontrol: avoid unused function warning

A bugfix in v4.8-rc2 introduced a harmless warning when CONFIG_MEMCG_SWAP
is disabled but CONFIG_MEMCG is enabled:

mm/memcontrol.c:4085:27: error: 'mem_cgroup_id_get_online' defined but not used [-Werror=unused-function]
 static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg)

This adds an extra #ifdef that matches the one around the caller to
avoid the warning.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
Fixes: 1f47b61fb407 ("mm: memcontrol: fix swap counter leak on swapout from offline cgroup")
---
 mm/memcontrol.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2ff0289ad061..e8d787163b65 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4082,6 +4082,7 @@ static void mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned int n)
 	atomic_add(n, &memcg->id.ref);
 }
 
+#ifdef CONFIG_MEMCG_SWAP
 static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg)
 {
 	while (!atomic_inc_not_zero(&memcg->id.ref)) {
@@ -4099,6 +4100,7 @@ static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg)
 	}
 	return memcg;
 }
+#endif
 
 static void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n)
 {
-- 
2.9.0