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memcg: move charges of anonymous swap

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This patch is another core part of this move-charge-at-task-migration
feature.  It enables moving charges of anonymous swaps.

To move the charge of swap, we need to exchange swap_cgroup's record.

In current implementation, swap_cgroup's record is protected by:

  - page lock: if the entry is on swap cache.
  - swap_lock: if the entry is not on swap cache.

This works well in usual swap-in/out activity.

But this behavior make the feature of moving swap charge check many
conditions to exchange swap_cgroup's record safely.

So I changed modification of swap_cgroup's recored(swap_cgroup_record())
to use xchg, and define a new function to cmpxchg swap_cgroup's record.

This patch also enables moving charge of non pte_present but not uncharged
swap caches, which can be exist on swap-out path, by getting the target
pages via find_get_page() as do_mincore() does.

[kosaki.motohiro@jp.fujitsu.com: fix ia64 build]
[akpm@linux-foundation.org: fix typos]
Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Daisuke Nishimura
2010-03-10 15:22:17 -08:00
committed by Linus Torvalds
parent 8033b97c9b
commit 024914477e
6 changed files with 225 additions and 40 deletions
Download Patch File Download Diff File Expand all files Collapse all files

34
mm/page_cgroup.c
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@@ -334,6 +334,37 @@ not_enough_page:
return -ENOMEM;
}
/**
* swap_cgroup_cmpxchg - cmpxchg mem_cgroup's id for this swp_entry.
* @end: swap entry to be cmpxchged
* @old: old id
* @new: new id
*
* Returns old id at success, 0 at failure.
* (There is no mem_cgroup useing 0 as its id)
*/
unsigned short swap_cgroup_cmpxchg(swp_entry_t ent,
unsigned short old, unsigned short new)
{
int type = swp_type(ent);
unsigned long offset = swp_offset(ent);
unsigned long idx = offset / SC_PER_PAGE;
unsigned long pos = offset & SC_POS_MASK;
struct swap_cgroup_ctrl *ctrl;
struct page *mappage;
struct swap_cgroup *sc;
ctrl = &swap_cgroup_ctrl[type];
mappage = ctrl->map[idx];
sc = page_address(mappage);
sc += pos;
if (cmpxchg(&sc->id, old, new) == old)
return old;
else
return 0;
}
/**
* swap_cgroup_record - record mem_cgroup for this swp_entry.
* @ent: swap entry to be recorded into
@@ -358,8 +389,7 @@ unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id)
mappage = ctrl->map[idx];
sc = page_address(mappage);
sc += pos;
old = sc->id;
sc->id = id;
old = xchg(&sc->id, id);
return old;
}