3.16.40-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: wangguang <wang.guang55@xxxxxxxxxx> 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@xxxxxxx> Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- 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); }