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.
Cc: stable@vger.kernel.org Signed-off-by: wangguang wangguang03@zte.com Signed-off-by: Theodore Ts'o tytso@mit.edu [@nathanchance: Resolved conflict from lack of 09cbfeaf1a5a6] Signed-off-by: Nathan Chancellor natechancellor@gmail.com --- One more bug fix I came across, sorry I forgot to send it with the other two patches! --- fs/ext4/inode.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index f0cabc8c96cb..3bddd47660d8 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1515,6 +1515,8 @@ static void mpage_release_unused_pages(struct mpage_da_data *mpd, 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); }