Re: [PATCH v2] jbd2: allocate lock_class_key for jbd2_handle dynamically

Jan Kara
2025-10-31T12:42:16Z

On Fri 31-10-25 20:28:34, Tetsuo Handa wrote:
> Who can take this patch?

Ted should pick it up. He's in CC so I'm sure he'll eventually get to it
when gathering patches for the next merge window.

Honza

>
> On 2025/10/23 16:59, Jan Kara wrote:
> > On Wed 22-10-25 20:11:37, Tetsuo Handa wrote:
> >> syzbot is reporting possibility of deadlock due to sharing lock_class_key
> >> for jbd2_handle across ext4 and ocfs2. But this is a false positive, for
> >> one disk partition can't have two filesystems at the same time.
> >>
> >> Reported-by: syzbot+6e493c165d26d6fcbf72@syzkaller.appspotmail.com
> >> Closes: https://syzkaller.appspot.com/bug?extid=6e493c165d26d6fcbf72
> >> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> >> Tested-by: syzbot+6e493c165d26d6fcbf72@syzkaller.appspotmail.com
> >
> > Thanks! Tha patch looks good. Feel free to add:
> >
> > Reviewed-by: Jan Kara <jack@suse.cz>
> >
> > Honza
> >
> >> ---
> >> fs/jbd2/journal.c | 6 ++++--
> >> include/linux/jbd2.h | 6 ++++++
> >> 2 files changed, 10 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
> >> index d480b94117cd..f43474002f50 100644
> >> --- a/fs/jbd2/journal.c
> >> +++ b/fs/jbd2/journal.c
> >> @@ -1521,7 +1521,6 @@ static journal_t *journal_init_common(struct block_device *bdev,
> >> struct block_device *fs_dev,
> >> unsigned long long start, int len, int blocksize)
> >> {
> >> - static struct lock_class_key jbd2_trans_commit_key;
> >> journal_t *journal;
> >> int err;
> >> int n;
> >> @@ -1530,6 +1529,7 @@ static journal_t *journal_init_common(struct block_device *bdev,
> >> if (!journal)
> >> return ERR_PTR(-ENOMEM);
> >>
> >> + lockdep_register_key(&journal->jbd2_trans_commit_key);
> >> journal->j_blocksize = blocksize;
> >> journal->j_dev = bdev;
> >> journal->j_fs_dev = fs_dev;
> >> @@ -1560,7 +1560,7 @@ static journal_t *journal_init_common(struct block_device *bdev,
> >> journal->j_max_batch_time = 15000; /* 15ms */
> >> atomic_set(&journal->j_reserved_credits, 0);
> >> lockdep_init_map(&journal->j_trans_commit_map, "jbd2_handle",
> >> - &jbd2_trans_commit_key, 0);
> >> + &journal->jbd2_trans_commit_key, 0);
> >>
> >> /* The journal is marked for error until we succeed with recovery! */
> >> journal->j_flags = JBD2_ABORT;
> >> @@ -1611,6 +1611,7 @@ static journal_t *journal_init_common(struct block_device *bdev,
> >> kfree(journal->j_wbuf);
> >> jbd2_journal_destroy_revoke(journal);
> >> journal_fail_superblock(journal);
> >> + lockdep_unregister_key(&journal->jbd2_trans_commit_key);
> >> kfree(journal);
> >> return ERR_PTR(err);
> >> }
> >> @@ -2187,6 +2188,7 @@ int jbd2_journal_destroy(journal_t *journal)
> >> jbd2_journal_destroy_revoke(journal);
> >> kfree(journal->j_fc_wbuf);
> >> kfree(journal->j_wbuf);
> >> + lockdep_unregister_key(&journal->jbd2_trans_commit_key);
> >> kfree(journal);
> >>
> >> return err;
> >> diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
> >> index 43b9297fe8a7..f5eaf76198f3 100644
> >> --- a/include/linux/jbd2.h
> >> +++ b/include/linux/jbd2.h
> >> @@ -1253,6 +1253,12 @@ struct journal_s
> >> */
> >> struct lockdep_map j_trans_commit_map;
> >> #endif
> >> + /**
> >> + * @jbd2_trans_commit_key:
> >> + *
> >> + * "struct lock_class_key" for @j_trans_commit_map
> >> + */
> >> + struct lock_class_key jbd2_trans_commit_key;
> >>
> >> /**
> >> * @j_fc_cleanup_callback:
> >> --
> >> 2.47.3
> >>
> >>
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR