1 files changed, 26 insertions, 21 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 29501f040568..5177c6d4a2dd 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1077,9 +1077,18 @@ static struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
 
         rcu_read_lock();
         do {
-                memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
-                if (unlikely(!memcg))
+                /*
+                 * Page cache insertions can happen withou an
+                 * actual mm context, e.g. during disk probing
+                 * on boot, loopback IO, acct() writes etc.
+                 */
+                if (unlikely(!mm))
                         memcg = root_mem_cgroup;
+                else {
+                        memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
+                        if (unlikely(!memcg))
+                                memcg = root_mem_cgroup;
+                }
         } while (!css_tryget(&memcg->css));
         rcu_read_unlock();
         return memcg;
@@ -3958,17 +3967,9 @@ int mem_cgroup_charge_file(struct page *page, struct mm_struct *mm,
                 return 0;
         }
 
-        /*
-         * Page cache insertions can happen without an actual mm
-         * context, e.g. during disk probing on boot.
-         */
-        if (unlikely(!mm))
-                memcg = root_mem_cgroup;
-        else {
-                memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, 1, true);
-                if (!memcg)
-                        return -ENOMEM;
-        }
+        memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, 1, true);
+        if (!memcg)
+                return -ENOMEM;
         __mem_cgroup_commit_charge(memcg, page, 1, type, false);
         return 0;
 }
@@ -6686,16 +6687,20 @@ static struct page *mc_handle_file_pte(struct vm_area_struct *vma,
                 pgoff = pte_to_pgoff(ptent);
 
         /* page is moved even if it's not RSS of this task(page-faulted). */
-        page = find_get_page(mapping, pgoff);
-
 #ifdef CONFIG_SWAP
         /* shmem/tmpfs may report page out on swap: account for that too. */
-        if (radix_tree_exceptional_entry(page)) {
-                swp_entry_t swap = radix_to_swp_entry(page);
-                if (do_swap_account)
-                        *entry = swap;
-                page = find_get_page(swap_address_space(swap), swap.val);
-        }
+        if (shmem_mapping(mapping)) {
+                page = find_get_entry(mapping, pgoff);
+                if (radix_tree_exceptional_entry(page)) {
+                        swp_entry_t swp = radix_to_swp_entry(page);
+                        if (do_swap_account)
+                                *entry = swp;
+                        page = find_get_page(swap_address_space(swp), swp.val);
+                }
+        } else
+                page = find_get_page(mapping, pgoff);
+#else
+        page = find_get_page(mapping, pgoff);
 #endif
         return page;
 }