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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: 1f47b61fb4 ("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>
This commit is contained in:
Arnd Bergmann 2016-08-25 15:17:08 -07:00 committed by Linus Torvalds
parent b32eaf71db
commit 358c07fcc3
1 changed files with 18 additions and 18 deletions
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36
mm/memcontrol.c
View File

@ -4082,24 +4082,6 @@ static void mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned int n)
atomic_add(n, &memcg->id.ref); 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) static void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n)
{ {
if (atomic_sub_and_test(n, &memcg->id.ref)) { 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); subsys_initcall(mem_cgroup_init);
#ifdef CONFIG_MEMCG_SWAP #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 * mem_cgroup_swapout - transfer a memsw charge to swap
* @page: page whose memsw charge to transfer * @page: page whose memsw charge to transfer