From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964795Ab2DXWn6 (ORCPT ); Tue, 24 Apr 2012 18:43:58 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:38637 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932887Ab2DXWiW (ORCPT ); Tue, 24 Apr 2012 18:38:22 -0400 Message-Id: <20120424223254.775060804@linuxfoundation.org> User-Agent: quilt/0.60-19.1 Date: Tue, 24 Apr 2012 15:33:08 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Mel Gorman , Hugh Dickins , Martin Schwidefsky , Heiko Carstens , Rik van Riel , Ken Chen Subject: [ 15/42] mm: fix s390 BUG by __set_page_dirty_no_writeback on swap In-Reply-To: <20120424223311.GA8456@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.0-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: Greg Kroah-Hartman --- mm/swap_state.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -28,7 +28,7 @@ */ 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, };