The patch titled
Subject: ocfs2: fix crash in ocfs2_duplicate_clusters_by_page()
has been added to the -mm tree. Its filename is
fix-crash-on-ocfs2_duplicate_clusters_by_page.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/fix-crash-on-ocfs2_duplicate_clusters_by_page.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/fix-crash-on-ocfs2_duplicate_clusters_by_page.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Larry Chen <lchen@xxxxxxxx>
Subject: ocfs2: fix crash in ocfs2_duplicate_clusters_by_page()
ocfs2_duplicate_clusters_by_page() may crash if one of the extent's pages
is dirty. When a page has not been written back, it is still in dirty
state. If ocfs2_duplicate_clusters_by_page() is called against the dirty
page, the crash happens.
To fix this bug, we can just unlock the page and wait until the page until
its not dirty.
The following is the backtrace:
kernel BUG at /root/code/ocfs2/refcounttree.c:2961!
[exception RIP: ocfs2_duplicate_clusters_by_page+822]
__ocfs2_move_extent+0x80/0x450 [ocfs2]
? __ocfs2_claim_clusters+0x130/0x250 [ocfs2]
ocfs2_defrag_extent+0x5b8/0x5e0 [ocfs2]
__ocfs2_move_extents_range+0x2a4/0x470 [ocfs2]
ocfs2_move_extents+0x180/0x3b0 [ocfs2]
? ocfs2_wait_for_recovery+0x13/0x70 [ocfs2]
ocfs2_ioctl_move_extents+0x133/0x2d0 [ocfs2]
ocfs2_ioctl+0x253/0x640 [ocfs2]
do_vfs_ioctl+0x90/0x5f0
SyS_ioctl+0x74/0x80
do_syscall_64+0x74/0x140
entry_SYSCALL_64_after_hwframe+0x3d/0xa2
Once we find the page is dirty, we do not wait until it's clean, rather we
use write_one_page() to write it back
Link: http://lkml.kernel.org/r/20180829074740.9438-1-lchen@xxxxxxxx
Signed-off-by: Larry Chen <lchen@xxxxxxxx>
Cc: Mark Fasheh <mark@xxxxxxxxxx>
Cc: Joel Becker <jlbec@xxxxxxxxxxxx>
Cc: Junxiao Bi <junxiao.bi@xxxxxxxxxx>
Cc: Joseph Qi <jiangqi903@xxxxxxxxx>
Cc: Changwei Ge <ge.changwei@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/ocfs2/refcounttree.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
--- a/fs/ocfs2/refcounttree.c~fix-crash-on-ocfs2_duplicate_clusters_by_page
+++ a/fs/ocfs2/refcounttree.c
@@ -2946,6 +2946,7 @@ int ocfs2_duplicate_clusters_by_page(han
if (map_end & (PAGE_SIZE - 1))
to = map_end & (PAGE_SIZE - 1);
+retry:
page = find_or_create_page(mapping, page_index, GFP_NOFS);
if (!page) {
ret = -ENOMEM;
@@ -2957,8 +2958,15 @@ int ocfs2_duplicate_clusters_by_page(han
* In case PAGE_SIZE <= CLUSTER_SIZE, This page
* can't be dirtied before we CoW it out.
*/
- if (PAGE_SIZE <= OCFS2_SB(sb)->s_clustersize)
- BUG_ON(PageDirty(page));
+ if (PAGE_SIZE <= OCFS2_SB(sb)->s_clustersize) {
+ if (PageDirty(page)) {
+ /*
+ * write_on_page will unlock the page on return
+ */
+ ret = write_one_page(page);
+ goto retry;
+ }
+ }
if (!PageUptodate(page)) {
ret = block_read_full_page(page, ocfs2_get_block);
_
Patches currently in -mm which might be from lchen@xxxxxxxx are
fix-dead-lock-caused-by-ocfs2_defrag_extent.patch
fix-crash-on-ocfs2_duplicate_clusters_by_page.patch
