* Patch "ext4: bugfix for mmaped pages in mpage_release_unused_pages()" has been added to the 4.8-stable tree
@ 2016-10-20 15:54 gregkh
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From: gregkh @ 2016-10-20 15:54 UTC (permalink / raw)
To: wang.guang55, gregkh, tytso, wangguang03; +Cc: stable, stable-commits
This is a note to let you know that I've just added the patch titled
ext4: bugfix for mmaped pages in mpage_release_unused_pages()
to the 4.8-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:
ext4-bugfix-for-mmaped-pages-in-mpage_release_unused_pages.patch
and it can be found in the queue-4.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
>From 4e800c0359d9a53e6bf0ab216954971b2515247f Mon Sep 17 00:00:00 2001
From: wangguang <wang.guang55@zte.com.cn>
Date: Thu, 15 Sep 2016 11:32:46 -0400
Subject: ext4: bugfix for mmaped pages in mpage_release_unused_pages()
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From: wangguang <wang.guang55@zte.com.cn>
commit 4e800c0359d9a53e6bf0ab216954971b2515247f upstream.
Pages clear buffers after ext4 delayed block allocation failed,
However, it does not clean its pte_dirty flag.
if the pages unmap ,in cording to the pte_dirty ,
unmap_page_range may try to call __set_page_dirty,
which may lead to the bugon at
mpage_prepare_extent_to_map:head = page_buffers(page);.
This patch just call clear_page_dirty_for_io to clean pte_dirty
at mpage_release_unused_pages for pages mmaped.
Steps to reproduce the bug:
(1) mmap a file in ext4
addr = (char *)mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_SHARED,
fd, 0);
memset(addr, 'i', 4096);
(2) return EIO at
ext4_writepages->mpage_map_and_submit_extent->mpage_map_one_extent
which causes this log message to be print:
ext4_msg(sb, KERN_CRIT,
"Delayed block allocation failed for "
"inode %lu at logical offset %llu with"
" max blocks %u with error %d",
inode->i_ino,
(unsigned long long)map->m_lblk,
(unsigned)map->m_len, -err);
(3)Unmap the addr cause warning at
__set_page_dirty:WARN_ON_ONCE(warn && !PageUptodate(page));
(4) wait for a minute,then bugon happen.
Signed-off-by: wangguang <wangguang03@zte.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/ext4/inode.c | 2 ++
1 file changed, 2 insertions(+)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1649,6 +1649,8 @@ static void mpage_release_unused_pages(s
BUG_ON(!PageLocked(page));
BUG_ON(PageWriteback(page));
if (invalidate) {
+ if (page_mapped(page))
+ clear_page_dirty_for_io(page);
block_invalidatepage(page, 0, PAGE_SIZE);
ClearPageUptodate(page);
}
Patches currently in stable-queue which might be from wang.guang55@zte.com.cn are
queue-4.8/ext4-bugfix-for-mmaped-pages-in-mpage_release_unused_pages.patch
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2016-10-20 15:54 Patch "ext4: bugfix for mmaped pages in mpage_release_unused_pages()" has been added to the 4.8-stable tree gregkh
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