memcg: cleanup cache_charge

Current mem_cgroup_cache_charge is a bit complicated especially
in the case of shmem's swap-in.

This patch cleans it up by using try_charge_swapin and commit_charge_swapin.

Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 23 insertions, 37 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 55dea5968464..2fc6d6c48238 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1238,6 +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)
 {
@@ -1274,16 +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;
 
@@ -1291,32 +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)};
-                unsigned short id;
-                /* avoid double counting */
-                id = swap_cgroup_record(ent, 0);
-                rcu_read_lock();
-                mem = mem_cgroup_lookup(id);
-                if (mem) {
-                        /*
-                         * We did swap-in. Then, this entry is doubly counted
-                         * both in mem and memsw. We uncharge it, here.
-                         * Recorded ID can be obsolete. We avoid calling
-                         * css_tryget()
-                         */
-                        res_counter_uncharge(&mem->memsw, PAGE_SIZE);
-                        mem_cgroup_put(mem);
-                }
-                rcu_read_unlock();
-        }
         return ret;
 }
 
@@ -1359,7 +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;
 
@@ -1369,7 +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
@@ -1400,6 +1380,12 @@ void mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *ptr)
 
 }
 
+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())