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-rw-r--r--mm/memcontrol.c24
1 files changed, 8 insertions, 16 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c3f09b2dda5f..0a06628470cc 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -460,6 +460,12 @@ static inline unsigned short mem_cgroup_id(struct mem_cgroup *memcg)
460 return memcg->css.id; 460 return memcg->css.id;
461} 461}
462 462
463/*
464 * A helper function to get mem_cgroup from ID. must be called under
465 * rcu_read_lock(). The caller is responsible for calling
466 * css_tryget_online() if the mem_cgroup is used for charging. (dropping
467 * refcnt from swap can be called against removed memcg.)
468 */
463static inline struct mem_cgroup *mem_cgroup_from_id(unsigned short id) 469static inline struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
464{ 470{
465 struct cgroup_subsys_state *css; 471 struct cgroup_subsys_state *css;
@@ -2349,20 +2355,6 @@ static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages)
2349} 2355}
2350 2356
2351/* 2357/*
2352 * A helper function to get mem_cgroup from ID. must be called under
2353 * rcu_read_lock(). The caller is responsible for calling
2354 * css_tryget_online() if the mem_cgroup is used for charging. (dropping
2355 * refcnt from swap can be called against removed memcg.)
2356 */
2357static struct mem_cgroup *mem_cgroup_lookup(unsigned short id)
2358{
2359 /* ID 0 is unused ID */
2360 if (!id)
2361 return NULL;
2362 return mem_cgroup_from_id(id);
2363}
2364
2365/*
2366 * try_get_mem_cgroup_from_page - look up page's memcg association 2358 * try_get_mem_cgroup_from_page - look up page's memcg association
2367 * @page: the page 2359 * @page: the page
2368 * 2360 *
@@ -2388,7 +2380,7 @@ struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
2388 ent.val = page_private(page); 2380 ent.val = page_private(page);
2389 id = lookup_swap_cgroup_id(ent); 2381 id = lookup_swap_cgroup_id(ent);
2390 rcu_read_lock(); 2382 rcu_read_lock();
2391 memcg = mem_cgroup_lookup(id); 2383 memcg = mem_cgroup_from_id(id);
2392 if (memcg && !css_tryget_online(&memcg->css)) 2384 if (memcg && !css_tryget_online(&memcg->css))
2393 memcg = NULL; 2385 memcg = NULL;
2394 rcu_read_unlock(); 2386 rcu_read_unlock();
@@ -5869,7 +5861,7 @@ void mem_cgroup_uncharge_swap(swp_entry_t entry)
5869 5861
5870 id = swap_cgroup_record(entry, 0); 5862 id = swap_cgroup_record(entry, 0);
5871 rcu_read_lock(); 5863 rcu_read_lock();
5872 memcg = mem_cgroup_lookup(id); 5864 memcg = mem_cgroup_from_id(id);
5873 if (memcg) { 5865 if (memcg) {
5874 if (!mem_cgroup_is_root(memcg)) 5866 if (!mem_cgroup_is_root(memcg))
5875 page_counter_uncharge(&memcg->memsw, 1); 5867 page_counter_uncharge(&memcg->memsw, 1);