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Commit 358c07fc authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Linus Torvalds
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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 moves the function inside of the #ifdef block that hides the
calling function, to avoid the warning.

Fixes: 1f47b61f ("mm: memcontrol: fix swap counter leak on swapout from offline cgroup")
Link: http://lkml.kernel.org/r/20160824113733.2776701-1-arnd@arndb.de


Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Acked-by: default avatarVladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b32eaf71

mm/memcontrol.c

+18 −18
Original line number Diff line number Diff line
@@ -4082,24 +4082,6 @@ static void mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned int n) 
	atomic_add(n, &memcg->id.ref);

}



static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg)

{

	while (!atomic_inc_not_zero(&memcg->id.ref)) {

		/*

		 * The root cgroup cannot be destroyed, so it's refcount must

		 * always be >= 1.

		 */

		if (WARN_ON_ONCE(memcg == root_mem_cgroup)) {

			VM_BUG_ON(1);

			break;

		}

		memcg = parent_mem_cgroup(memcg);

		if (!memcg)

			memcg = root_mem_cgroup;

	}

	return memcg;

}



static void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n)

{

	if (atomic_sub_and_test(n, &memcg->id.ref)) {
@@ -5821,6 +5803,24 @@ static int __init mem_cgroup_init(void) 
subsys_initcall(mem_cgroup_init);



#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)) {

		/*

		 * The root cgroup cannot be destroyed, so it's refcount must

		 * always be >= 1.

		 */

		if (WARN_ON_ONCE(memcg == root_mem_cgroup)) {

			VM_BUG_ON(1);

			break;

		}

		memcg = parent_mem_cgroup(memcg);

		if (!memcg)

			memcg = root_mem_cgroup;

	}

	return memcg;

}



/**

 * mem_cgroup_swapout - transfer a memsw charge to swap

 * @page: page whose memsw charge to transfer