memcg: fix shmem's swap accounting

Now, you can see following even when swap accounting is enabled.

 1. Create Group 01, and 02.
 2. allocate a "file" on tmpfs by a task under 01.
 3. swap out the "file" (by memory pressure)
 4. Read "file" from a task in group 02.
 5. the charge of "file" is moved to group 02.

This is not ideal behavior. This is because SwapCache which was loaded
by read-ahead is not taken into account..

This is a patch to fix shmem's swapcache behavior.
  - remove mem_cgroup_cache_charge_swapin().
  - Add SwapCache handler routine to mem_cgroup_cache_charge().
    By this, shmem's file cache is charged at add_to_page_cache()
    with GFP_NOWAIT.
  - pass the page of swapcache to shrink_mem_cgroup.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 8 deletions

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 4ccca25d0f05..d30215578877 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -335,16 +335,8 @@ static inline void disable_swap_token(void)
 }
 
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
-extern int mem_cgroup_cache_charge_swapin(struct page *page,
-                                struct mm_struct *mm, gfp_t mask, bool locked);
 extern void mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent);
 #else
-static inline
-int mem_cgroup_cache_charge_swapin(struct page *page,
-                                struct mm_struct *mm, gfp_t mask, bool locked)
-{
-        return 0;
-}
 static inline void
 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
 {