Messages in this thread Patch in this message | | | Subject | [PATCH] ext4: bugfix for mmaped pages in mpage_release_unused_pages() | From | wang.guang55@zte ... | Date | Tue, 9 Aug 2016 16:43:26 +0800 |
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ext4: bugfix for mmaped pages in mpage_release_unused_pages()
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->ext4_map_blocks Cause the log: 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 case warning at __set_page_dirty: (4) wait for a minute,then bugon happen.
diff -uprN linux-3.10.102/fs/ext4/inode.c linux-3.10.102_new/fs/ext4/inode.c --- linux-3.10.102/fs/ext4/inode.c 2016-08-09 04:06:59.000000000 -0400 +++ linux-3.10.102_new/fs/ext4/inode.c 2016-08-09 04:09:26.000000000 -0400 @@ -1465,6 +1465,10 @@ 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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