memcg: cleanup cache_charge

[sfrench/cifs-2.6.git] / mm / memcontrol.c

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 81b0ae8183d0b04e3e0924823732020da2777ded..2fc6d6c482387ed35a735746bf4580d3d38e68da 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -991,10 +991,31 @@ nomem:
        return -ENOMEM;
 }
 
+
+/*
+ * A helper function to get mem_cgroup from ID. must be called under
+ * rcu_read_lock(). The caller must check css_is_removed() or some if
+ * it's concern. (dropping refcnt from swap can be called against removed
+ * memcg.)
+ */
+static struct mem_cgroup *mem_cgroup_lookup(unsigned short id)
+{
+       struct cgroup_subsys_state *css;
+
+       /* ID 0 is unused ID */
+       if (!id)
+               return NULL;
+       css = css_lookup(&mem_cgroup_subsys, id);
+       if (!css)
+               return NULL;
+       return container_of(css, struct mem_cgroup, css);
+}
+
 static struct mem_cgroup *try_get_mem_cgroup_from_swapcache(struct page *page)
 {
        struct mem_cgroup *mem;
        struct page_cgroup *pc;
+       unsigned short id;
        swp_entry_t ent;
 
        VM_BUG_ON(!PageLocked(page));
@@ -1006,16 +1027,19 @@ static struct mem_cgroup *try_get_mem_cgroup_from_swapcache(struct page *page)
        /*
         * Used bit of swapcache is solid under page lock.
         */
-       if (PageCgroupUsed(pc))
+       if (PageCgroupUsed(pc)) {
                mem = pc->mem_cgroup;
-       else {
+               if (mem && !css_tryget(&mem->css))
+                       mem = NULL;
+       } else {
                ent.val = page_private(page);
-               mem = lookup_swap_cgroup(ent);
+               id = lookup_swap_cgroup(ent);
+               rcu_read_lock();
+               mem = mem_cgroup_lookup(id);
+               if (mem && !css_tryget(&mem->css))
+                       mem = NULL;
+               rcu_read_unlock();
        }
-       if (!mem)
-               return NULL;
-       if (!css_tryget(&mem->css))
-               return NULL;
        return mem;
 }
 
@@ -1214,6 +1238,10 @@ int mem_cgroup_newpage_charge(struct page *page,
                                MEM_CGROUP_CHARGE_TYPE_MAPPED, NULL);
 }
 
+static void
+__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
+                                       enum charge_type ctype);
+
 int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
                                gfp_t gfp_mask)
 {
@@ -1250,16 +1278,6 @@ int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
                unlock_page_cgroup(pc);
        }
 
-       if (do_swap_account && PageSwapCache(page)) {
-               mem = try_get_mem_cgroup_from_swapcache(page);
-               if (mem)
-                       mm = NULL;
-                 else
-                       mem = NULL;
-               /* SwapCache may be still linked to LRU now. */
-               mem_cgroup_lru_del_before_commit_swapcache(page);
-       }
-
        if (unlikely(!mm && !mem))
                mm = &init_mm;
 
@@ -1267,22 +1285,16 @@ int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
                return mem_cgroup_charge_common(page, mm, gfp_mask,
                                MEM_CGROUP_CHARGE_TYPE_CACHE, NULL);
 
-       ret = mem_cgroup_charge_common(page, mm, gfp_mask,
-                               MEM_CGROUP_CHARGE_TYPE_SHMEM, mem);
-       if (mem)
-               css_put(&mem->css);
-       if (PageSwapCache(page))
-               mem_cgroup_lru_add_after_commit_swapcache(page);
+       /* shmem */
+       if (PageSwapCache(page)) {
+               ret = mem_cgroup_try_charge_swapin(mm, page, gfp_mask, &mem);
+               if (!ret)
+                       __mem_cgroup_commit_charge_swapin(page, mem,
+                                       MEM_CGROUP_CHARGE_TYPE_SHMEM);
+       } else
+               ret = mem_cgroup_charge_common(page, mm, gfp_mask,
+                                       MEM_CGROUP_CHARGE_TYPE_SHMEM, mem);
 
-       if (do_swap_account && !ret && PageSwapCache(page)) {
-               swp_entry_t ent = {.val = page_private(page)};
-               /* avoid double counting */
-               mem = swap_cgroup_record(ent, NULL);
-               if (mem) {
-                       res_counter_uncharge(&mem->memsw, PAGE_SIZE);
-                       mem_cgroup_put(mem);
-               }
-       }
        return ret;
 }
 
@@ -1325,7 +1337,9 @@ charge_cur_mm:
        return __mem_cgroup_try_charge(mm, mask, ptr, true);
 }
 
-void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr)
+static void
+__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
+                                       enum charge_type ctype)
 {
        struct page_cgroup *pc;
 
@@ -1335,7 +1349,7 @@ void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr)
                return;
        pc = lookup_page_cgroup(page);
        mem_cgroup_lru_del_before_commit_swapcache(page);
-       __mem_cgroup_commit_charge(ptr, pc, MEM_CGROUP_CHARGE_TYPE_MAPPED);
+       __mem_cgroup_commit_charge(ptr, pc, ctype);
        mem_cgroup_lru_add_after_commit_swapcache(page);
        /*
         * Now swap is on-memory. This means this page may be
@@ -1346,18 +1360,32 @@ void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr)
         */
        if (do_swap_account && PageSwapCache(page)) {
                swp_entry_t ent = {.val = page_private(page)};
+               unsigned short id;
                struct mem_cgroup *memcg;
-               memcg = swap_cgroup_record(ent, NULL);
+
+               id = swap_cgroup_record(ent, 0);
+               rcu_read_lock();
+               memcg = mem_cgroup_lookup(id);
                if (memcg) {
+                       /*
+                        * This recorded memcg can be obsolete one. So, avoid
+                        * calling css_tryget
+                        */
                        res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
                        mem_cgroup_put(memcg);
                }
-
+               rcu_read_unlock();
        }
        /* add this page(page_cgroup) to the LRU we want. */
 
 }
 
+void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr)
+{
+       __mem_cgroup_commit_charge_swapin(page, ptr,
+                                       MEM_CGROUP_CHARGE_TYPE_MAPPED);
+}
+
 void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *mem)
 {
        if (mem_cgroup_disabled())
@@ -1473,7 +1501,7 @@ void mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
                                        MEM_CGROUP_CHARGE_TYPE_SWAPOUT);
        /* record memcg information */
        if (do_swap_account && memcg) {
-               swap_cgroup_record(ent, memcg);
+               swap_cgroup_record(ent, css_id(&memcg->css));
                mem_cgroup_get(memcg);
        }
        if (memcg)
@@ -1488,15 +1516,23 @@ void mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
 void mem_cgroup_uncharge_swap(swp_entry_t ent)
 {
        struct mem_cgroup *memcg;
+       unsigned short id;
 
        if (!do_swap_account)
                return;
 
-       memcg = swap_cgroup_record(ent, NULL);
+       id = swap_cgroup_record(ent, 0);
+       rcu_read_lock();
+       memcg = mem_cgroup_lookup(id);
        if (memcg) {
+               /*
+                * We uncharge this because swap is freed.
+                * This memcg can be obsolete one. We avoid calling css_tryget
+                */
                res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
                mem_cgroup_put(memcg);
        }
+       rcu_read_unlock();
 }
 #endif