memcg: fix swapcache charge from kernel thread context

[cascardo/linux.git] / mm / memcontrol.c

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 29501f0..5177c6d 100644 (file)
--- 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;
 }