From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:59048 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753207AbdCHNOs (ORCPT ); Wed, 8 Mar 2017 08:14:48 -0500 Subject: Patch "mm: do not access page->mapping directly on page_endio" has been added to the 4.4-stable tree To: minchan@kernel.org, akpm@linux-foundation.org, gregkh@linuxfoundation.org, mhocko@suse.com, torvalds@linux-foundation.org, willy@infradead.org Cc: , From: Date: Wed, 08 Mar 2017 14:12:45 +0100 Message-ID: <148897876524989@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled mm: do not access page->mapping directly on page_endio to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mm-do-not-access-page-mapping-directly-on-page_endio.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From dd8416c47715cf324c9a16f13273f9fda87acfed Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Fri, 24 Feb 2017 14:59:59 -0800 Subject: mm: do not access page->mapping directly on page_endio From: Minchan Kim commit dd8416c47715cf324c9a16f13273f9fda87acfed upstream. With rw_page, page_endio is used for completing IO on a page and it propagates write error to the address space if the IO fails. The problem is it accesses page->mapping directly which might be okay for file-backed pages but it shouldn't for anonymous page. Otherwise, it can corrupt one of field from anon_vma under us and system goes panic randomly. swap_writepage bdev_writepage ops->rw_page I encountered the BUG during developing new zram feature and it was really hard to figure it out because it made random crash, somtime mmap_sem lockdep, sometime other places where places never related to zram/zsmalloc, and not reproducible with some configuration. When I consider how that bug is subtle and people do fast-swap test with brd, it's worth to add stable mark, I think. Fixes: dd6bd0d9c7db ("swap: use bdev_read_page() / bdev_write_page()") Signed-off-by: Minchan Kim Acked-by: Michal Hocko Cc: Matthew Wilcox Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/filemap.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/mm/filemap.c +++ b/mm/filemap.c @@ -865,9 +865,12 @@ void page_endio(struct page *page, int r unlock_page(page); } else { /* rw == WRITE */ if (err) { + struct address_space *mapping; + SetPageError(page); - if (page->mapping) - mapping_set_error(page->mapping, err); + mapping = page_mapping(page); + if (mapping) + mapping_set_error(mapping, err); } end_page_writeback(page); } Patches currently in stable-queue which might be from minchan@kernel.org are queue-4.4/mm-vmpressure-fix-sending-wrong-events-on-underflow.patch queue-4.4/mm-do-not-access-page-mapping-directly-on-page_endio.patch