| From | Ben Hutchings <> | Date | Wed, 15 Feb 2017 22:41:40 +0000 | Subject | [PATCH 3.16 046/306] ext4: bugfix for mmaped pages in mpage_release_unused_pages() |
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3.16.40-rc1 review patch. If anyone has any objections, please let me know.
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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> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- fs/ext4/inode.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1494,6 +1494,8 @@ 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_CACHE_SIZE); ClearPageUptodate(page); }
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