lkml.org 
[lkml]   [2016]   [Aug]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Subject[PATCH] ext4: bugfix for mmaped pages in mpage_release_unused_pages()
From
Date
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);
}
















王广
Operation System Production Dept .
操作系统产品部

创新*突破*集约化
Add:成都市高新区天府大道中段800号中兴通讯大厦xxx室
Tel:13678197402




\
 
 \ /
  Last update: 2016-08-09 11:41    [W:0.037 / U:0.096 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site