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Subject[PATCH 1/6] memcg: move charge swapin under lock
While page-cache's charge/uncharge is done under page_lock(), swap-cache
isn't. (anonymous page is charged when it's newly allocated.)

This patch moves do_swap_page()'s charge() call under lock.
I don't see any bad problem *now* but this fix will be good for future
for avoiding unneccesary racy state.


Changelog: (v6) -> (v7)
- no changes.
Changelog: (v5) -> (v6)
- mark_page_accessed() is moved before lock_page().
- fixed missing unlock_page()
(no changes in previous version)

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>

mm/memory.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
Index: mmotm-2.6.27-rc7+/mm/memory.c
===================================================================
--- mmotm-2.6.27-rc7+.orig/mm/memory.c
+++ mmotm-2.6.27-rc7+/mm/memory.c
@@ -2326,16 +2326,17 @@ static int do_swap_page(struct mm_struct
count_vm_event(PGMAJFAULT);
}

+ mark_page_accessed(page);
+
+ lock_page(page);
+ delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
+
if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
- delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
ret = VM_FAULT_OOM;
+ unlock_page(page);
goto out;
}

- mark_page_accessed(page);
- lock_page(page);
- delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
-
/*
* Back out if somebody else already faulted in this pte.
*/


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