[PATCH 2/13] memcg: account fault-in swap under lock.

KAMEZAWA Hiroyuki
2008-09-22T10:57:41Z

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.
This is good for avoiding unnecessary slow-path in charge().

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

mm/memory.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

Index: mmotm-2.6.27-rc6+/mm/memory.c
===================================================================
--- mmotm-2.6.27-rc6+.orig/mm/memory.c
+++ mmotm-2.6.27-rc6+/mm/memory.c
@@ -2320,15 +2320,14 @@ static int do_swap_page(struct mm_struct
count_vm_event(PGMAJFAULT);
}

+ 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;
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.