From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:33674 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751763AbdJOOLs (ORCPT ); Sun, 15 Oct 2017 10:11:48 -0400 Subject: Patch "fix unbalanced page refcounting in bio_map_user_iov" has been added to the 4.4-stable tree To: v.mayatskih@gmail.com, gregkh@linuxfoundation.org, viro@zeniv.linux.org.uk Cc: , From: Date: Sun, 15 Oct 2017 16:11:41 +0200 Message-ID: <150807670125324@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 fix unbalanced page refcounting in bio_map_user_iov 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: fix-unbalanced-page-refcounting-in-bio_map_user_iov.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 95d78c28b5a85bacbc29b8dba7c04babb9b0d467 Mon Sep 17 00:00:00 2001 From: Vitaly Mayatskikh Date: Fri, 22 Sep 2017 01:18:39 -0400 Subject: fix unbalanced page refcounting in bio_map_user_iov From: Vitaly Mayatskikh commit 95d78c28b5a85bacbc29b8dba7c04babb9b0d467 upstream. bio_map_user_iov and bio_unmap_user do unbalanced pages refcounting if IO vector has small consecutive buffers belonging to the same page. bio_add_pc_page merges them into one, but the page reference is never dropped. Signed-off-by: Vitaly Mayatskikh Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman --- block/bio.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/block/bio.c +++ b/block/bio.c @@ -1320,6 +1320,7 @@ struct bio *bio_map_user_iov(struct requ offset = uaddr & ~PAGE_MASK; for (j = cur_page; j < page_limit; j++) { unsigned int bytes = PAGE_SIZE - offset; + unsigned short prev_bi_vcnt = bio->bi_vcnt; if (len <= 0) break; @@ -1334,6 +1335,13 @@ struct bio *bio_map_user_iov(struct requ bytes) break; + /* + * check if vector was merged with previous + * drop page reference if needed + */ + if (bio->bi_vcnt == prev_bi_vcnt) + put_page(pages[j]); + len -= bytes; offset = 0; } Patches currently in stable-queue which might be from v.mayatskih@gmail.com are queue-4.4/fix-unbalanced-page-refcounting-in-bio_map_user_iov.patch