Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758182Ab2EIGYG (ORCPT ); Wed, 9 May 2012 02:24:06 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:38897 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756145Ab2EIFxO (ORCPT ); Wed, 9 May 2012 01:53:14 -0400 Message-Id: <20120509055032.760931560@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Wed, 09 May 2012 06:50:52 +0100 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Hugh Dickins , Mel Gorman , Martin Schwidefsky , Heiko Carstens , Rik van Riel , Ken Chen Subject: [ 023/167] [PATCH] mm: fix s390 BUG by __set_page_dirty_no_writeback on swap In-Reply-To: <20120509055029.588587017@decadent.org.uk> X-SA-Exim-Connect-IP: 192.168.4.185 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2459 Lines: 67 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hugh Dickins commit aca50bd3b4c4bb5528a1878158ba7abce41de534 upstream. Mel reports a BUG_ON(slot == NULL) in radix_tree_tag_set() on s390 3.0.13: called from __set_page_dirty_nobuffers() when page_remove_rmap() tries to transfer dirty flag from s390 storage key to struct page and radix_tree. That would be because of reclaim's shrink_page_list() calling add_to_swap() on this page at the same time: first PageSwapCache is set (causing page_mapping(page) to appear as &swapper_space), then page->private set, then tree_lock taken, then page inserted into radix_tree - so there's an interval before taking the lock when the radix_tree slot is empty. We could fix this by moving __add_to_swap_cache()'s spin_lock_irq up before the SetPageSwapCache. But a better fix is simply to do what's five years overdue: Ken Chen introduced __set_page_dirty_no_writeback() (if !PageDirty TestSetPageDirty) for tmpfs to skip all the radix_tree overhead, and swap is just the same - it ignores the radix_tree tag, and does not participate in dirty page accounting, so should be using __set_page_dirty_no_writeback() too. s390 testing now confirms that this does indeed fix the problem. Reported-by: Mel Gorman Signed-off-by: Hugh Dickins Acked-by: Mel Gorman Cc: Andrew Morton Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: Rik van Riel Cc: Ken Chen Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- mm/swap_state.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/swap_state.c b/mm/swap_state.c index 9d3dd37..4c5ff7f 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -26,7 +26,7 @@ */ static const struct address_space_operations swap_aops = { .writepage = swap_writepage, - .set_page_dirty = __set_page_dirty_nobuffers, + .set_page_dirty = __set_page_dirty_no_writeback, .migratepage = migrate_page, }; -- 1.7.10 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/