mm: memcontrol: avoid unused function warning (358c07fc) · Commits · 戴 / test

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: ("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:

Arnd Bergmann <arnd@arndb.de> Acked-by:

Michal Hocko <mhocko@suse.com> Acked-by:

Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

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

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