memcg: handle swap caches
authorKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Thu, 8 Jan 2009 02:07:56 +0000 (18:07 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 8 Jan 2009 16:31:05 +0000 (08:31 -0800)
commitd13d144309d2e5a3e6ad978b16c1d0226ddc9231
tree37c19902b527823956db969d9428737081b2a94d
parentc1e862c1f5ad34771b6d0a528cf681e0dcad7c86
memcg: handle swap caches

SwapCache support for memory resource controller (memcg)

Before mem+swap controller, memcg itself should handle SwapCache in proper
way.  This is cut-out from it.

In current memcg, SwapCache is just leaked and the user can create tons of
SwapCache.  This is a leak of account and should be handled.

SwapCache accounting is done as following.

  charge (anon)
- charged when it's mapped.
  (because of readahead, charge at add_to_swap_cache() is not sane)
  uncharge (anon)
- uncharged when it's dropped from swapcache and fully unmapped.
  means it's not uncharged at unmap.
  Note: delete from swap cache at swap-in is done after rmap information
        is established.
  charge (shmem)
- charged at swap-in. this prevents charge at add_to_page_cache().

  uncharge (shmem)
- uncharged when it's dropped from swapcache and not on shmem's
  radix-tree.

  at migration, check against 'old page' is modified to handle shmem.

Comparing to the old version discussed (and caused troubles), we have
advantages of
  - PCG_USED bit.
  - simple migrating handling.

So, situation is much easier than several months ago, maybe.

[hugh@veritas.com: memcg: handle swap caches build fix]
Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Tested-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Documentation/controllers/memory.txt
include/linux/swap.h
mm/memcontrol.c
mm/shmem.c
mm/swap_state.c