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authorDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>2010-03-10 15:22:17 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2010-03-12 15:52:36 -0800
commit024914477e15ef8b17f271ec47f1bb8a589f0806 (patch)
tree9a6a8b4224c94fcdd1b8c3127b301ee3537f8cc2 /mm/page_cgroup.c
parent8033b97c9b5ef063e3f4bf2efe1cd0a22093aaff (diff)
downloadlwn-024914477e15ef8b17f271ec47f1bb8a589f0806.tar.gz
lwn-024914477e15ef8b17f271ec47f1bb8a589f0806.zip
memcg: move charges of anonymous swap
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>
Diffstat (limited to 'mm/page_cgroup.c')
-rw-r--r--mm/page_cgroup.c34
1 files changed, 32 insertions, 2 deletions
diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c
index 3d535d594826..3dd88539a0e6 100644
--- a/mm/page_cgroup.c
+++ b/mm/page_cgroup.c
@@ -335,6 +335,37 @@ not_enough_page:
}
/**
+ * 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
* @mem: mem_cgroup to be recorded
@@ -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;
}