On Sun, Apr 22, 2018 at 02:45:16AM -0700, Nathan Chancellor wrote: > 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. > > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: wangguang <wangguang03@xxxxxxx> > Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> > [@nathanchance: Resolved conflict from lack of 09cbfeaf1a5a6] > Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx> > --- > One more bug fix I came across, sorry I forgot to send it with the other > two patches! Thanks for this, now applied. greg k-h