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 unnecessary racy state. Signed-off-by: KAMEZAWA Hiroyuki <[email protected]> Reviewed-by: Daisuke Nishimura <[email protected]> Acked-by: Balbir Singh <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
ericholscher · Oct 20, 2008 · 073e587 · 073e587
1 parent 47c5980
commit 073e587
Showing 1 changed file with 6 additions and 5 deletions.
diff --git a/mm/memory.c b/mm/memory.c
@@ -2326,16 +2326,17 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
 		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.
 	 */