1 files changed, 52 insertions, 18 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 61ffe712afe..1f0b460fe58 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -926,18 +926,28 @@ void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru)
 }
 
 /*
- * At handling SwapCache, pc->mem_cgroup may be changed while it's linked to
- * lru because the page may.be reused after it's fully uncharged (because of
- * SwapCache behavior).To handle that, unlink page_cgroup from LRU when charge
- * it again. This function is only used to charge SwapCache. It's done under
- * lock_page and expected that zone->lru_lock is never held.
+ * At handling SwapCache and other FUSE stuff, pc->mem_cgroup may be changed
+ * while it's linked to lru because the page may be reused after it's fully
+ * uncharged. To handle that, unlink page_cgroup from LRU when charge it again.
+ * It's done under lock_page and expected that zone->lru_lock isnever held.
  */
-static void mem_cgroup_lru_del_before_commit_swapcache(struct page *page)
+static void mem_cgroup_lru_del_before_commit(struct page *page)
 {
         unsigned long flags;
         struct zone *zone = page_zone(page);
         struct page_cgroup *pc = lookup_page_cgroup(page);
 
+        /*
+         * Doing this check without taking ->lru_lock seems wrong but this
+         * is safe. Because if page_cgroup's USED bit is unset, the page
+         * will not be added to any memcg's LRU. If page_cgroup's USED bit is
+         * set, the commit after this will fail, anyway.
+         * This all charge/uncharge is done under some mutual execustion.
+         * So, we don't need to taking care of changes in USED bit.
+         */
+        if (likely(!PageLRU(page)))
+                return;
+
         spin_lock_irqsave(&zone->lru_lock, flags);
         /*
          * Forget old LRU when this page_cgroup is *not* used. This Used bit
@@ -948,12 +958,15 @@ static void mem_cgroup_lru_del_before_commit_swapcache(struct page *page)
         spin_unlock_irqrestore(&zone->lru_lock, flags);
 }
 
-static void mem_cgroup_lru_add_after_commit_swapcache(struct page *page)
+static void mem_cgroup_lru_add_after_commit(struct page *page)
 {
         unsigned long flags;
         struct zone *zone = page_zone(page);
         struct page_cgroup *pc = lookup_page_cgroup(page);
 
+        /* taking care of that the page is added to LRU while we commit it */
+        if (likely(!PageLRU(page)))
+                return;
         spin_lock_irqsave(&zone->lru_lock, flags);
         /* link when the page is linked to LRU but page_cgroup isn't */
         if (PageLRU(page) && !PageCgroupAcctLRU(pc))
@@ -2431,9 +2444,26 @@ static void
 __mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
                                         enum charge_type ctype);
 
+static void
+__mem_cgroup_commit_charge_lrucare(struct page *page, struct mem_cgroup *mem,
+                                        enum charge_type ctype)
+{
+        struct page_cgroup *pc = lookup_page_cgroup(page);
+        /*
+         * In some case, SwapCache, FUSE(splice_buf->radixtree), the page
+         * is already on LRU. It means the page may on some other page_cgroup's
+         * LRU. Take care of it.
+         */
+        mem_cgroup_lru_del_before_commit(page);
+        __mem_cgroup_commit_charge(mem, page, 1, pc, ctype);
+        mem_cgroup_lru_add_after_commit(page);
+        return;
+}
+
 int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
                                 gfp_t gfp_mask)
 {
+        struct mem_cgroup *mem = NULL;
         int ret;
 
         if (mem_cgroup_disabled())
@@ -2468,14 +2498,22 @@ int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
         if (unlikely(!mm))
                 mm = &init_mm;
 
-        if (page_is_file_cache(page))
-                return mem_cgroup_charge_common(page, mm, gfp_mask,
-                                MEM_CGROUP_CHARGE_TYPE_CACHE);
+        if (page_is_file_cache(page)) {
+                ret = __mem_cgroup_try_charge(mm, gfp_mask, 1, &mem, true);
+                if (ret || !mem)
+                        return ret;
 
+                /*
+                 * FUSE reuses pages without going through the final
+                 * put that would remove them from the LRU list, make
+                 * sure that they get relinked properly.
+                 */
+                __mem_cgroup_commit_charge_lrucare(page, mem,
+                                        MEM_CGROUP_CHARGE_TYPE_CACHE);
+                return ret;
+        }
         /* shmem */
         if (PageSwapCache(page)) {
-                struct mem_cgroup *mem;
-
                 ret = mem_cgroup_try_charge_swapin(mm, page, gfp_mask, &mem);
                 if (!ret)
                         __mem_cgroup_commit_charge_swapin(page, mem,
@@ -2532,17 +2570,13 @@ static void
 __mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr,
                                         enum charge_type ctype)
 {
-        struct page_cgroup *pc;
-
         if (mem_cgroup_disabled())
                 return;
         if (!ptr)
                 return;
         cgroup_exclude_rmdir(&ptr->css);
-        pc = lookup_page_cgroup(page);
-        mem_cgroup_lru_del_before_commit_swapcache(page);
-        __mem_cgroup_commit_charge(ptr, page, 1, pc, ctype);
-        mem_cgroup_lru_add_after_commit_swapcache(page);
+
+        __mem_cgroup_commit_charge_lrucare(page, ptr, ctype);
         /*
          * Now swap is on-memory. This means this page may be
          * counted both as mem and swap....double count.