add patch fix-potential-use-after-free-after-remounting-with-noblock_validity
[ext4-patch-queue.git] / do-not-descrease-bufferheads-refcount
blob2d48e00e199c12b41860855ae4210de2fad406ee
1 jbd2: flush_descriptor(): Do not decrease buffer head's ref count
3 From: Chandan Rajendra <chandan@linux.ibm.com>
5 When executing generic/388 on a ppc64le machine, we notice the following
6 call trace,
8 VFS: brelse: Trying to free free buffer
9 WARNING: CPU: 0 PID: 6637 at /root/repos/linux/fs/buffer.c:1195 __brelse+0x84/0xc0
11 Call Trace:
12  __brelse+0x80/0xc0 (unreliable)
13  invalidate_bh_lru+0x78/0xc0
14  on_each_cpu_mask+0xa8/0x130
15  on_each_cpu_cond_mask+0x130/0x170
16  invalidate_bh_lrus+0x44/0x60
17  invalidate_bdev+0x38/0x70
18  ext4_put_super+0x294/0x560
19  generic_shutdown_super+0xb0/0x170
20  kill_block_super+0x38/0xb0
21  deactivate_locked_super+0xa4/0xf0
22  cleanup_mnt+0x164/0x1d0
23  task_work_run+0x110/0x160
24  do_notify_resume+0x414/0x460
25  ret_from_except_lite+0x70/0x74
27 The warning happens because flush_descriptor() drops bh reference it
28 does not own. The bh reference acquired by
29 jbd2_journal_get_descriptor_buffer() is owned by the log_bufs list and
30 gets released when this list is processed. The reference for doing IO is
31 only acquired in write_dirty_buffer() later in flush_descriptor().
33 Reported-by: Harish Sriram <harish@linux.ibm.com>
34 Reviewed-by: Jan Kara <jack@suse.cz>
35 Signed-off-by: Chandan Rajendra <chandan@linux.ibm.com>
36 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
37 ---
38 Changelog:
39 V1 -> V2:
40 1. Fix commit message.
42  fs/jbd2/revoke.c | 4 +---
43  1 file changed, 1 insertion(+), 3 deletions(-)
45 diff --git a/fs/jbd2/revoke.c b/fs/jbd2/revoke.c
46 index 69b9bc329964..f08073d7bbf5 100644
47 --- a/fs/jbd2/revoke.c
48 +++ b/fs/jbd2/revoke.c
49 @@ -638,10 +638,8 @@ static void flush_descriptor(journal_t *journal,
50  {
51         jbd2_journal_revoke_header_t *header;
53 -       if (is_journal_aborted(journal)) {
54 -               put_bh(descriptor);
55 +       if (is_journal_aborted(journal))
56                 return;
57 -       }
59         header = (jbd2_journal_revoke_header_t *)descriptor->b_data;
60         header->r_count = cpu_to_be32(offset);
61 -- 
62 2.19.1