linux-kernel - [resend][PATCH -mm] split_lru: fix pagevec_move

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Date:	Tue, 01 Jul 2008 17:26:51 +0900
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	LKML <linux-kernel@...r.kernel.org>, linux-mm <linux-mm@...ck.org>,
	Rik van Riel <riel@...hat.com>,
	Lee Schermerhorn <Lee.Schermerhorn@...com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"MinChan Kim" <minchan.kim@...il.com>
Cc:	kosaki.motohiro@...fujitsu.com
Subject: [resend][PATCH -mm] split_lru: fix pagevec_move_tail() doesn't treat unevictable page 


Agghh!
I am really stupid. I forgot CCed Andrew ;-)

So, I resend this.


--------------------------------------
even under writebacking, page can move to unevictable list.
so shouldn't pagevec_move_tail() check unevictable?

if pagevec_move_tail() doesn't PageUnevictable(), 
below race can occur.


    CPU1                                       CPU2
==================================================================
1. rotate_reclaimable_page()
2. PageUnevictable(page) return 0
3. local_irq_save()
4. pagevec_move_tail()
                                       SetPageUnevictable()   //mlock?
                                       move to unevictable list
5. spin_lock(&zone->lru_lock);
6. list_move_tail(); (move to inactive list)



Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>

---
 mm/swap.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: b/mm/swap.c
===================================================================
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -116,7 +116,7 @@ static void pagevec_move_tail(struct pag
 			zone = pagezone;
 			spin_lock(&zone->lru_lock);
 		}
-		if (PageLRU(page) && !PageActive(page)) {
+		if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
 			int lru = page_is_file_cache(page);
 			list_move_tail(&page->lru, &zone->lru[lru].list);
 			pgmoved++;




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