jbd2: allocate lock_class_key for jbd2_handle dynamically

[PATCH v2] jbd2: allocate lock_class_key for jbd2_handle dynamically

Posted by Tetsuo Handa 3 months, 2 weeks ago

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
---
 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

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

Posted by Theodore Ts'o 2 months, 3 weeks ago

On Wed, 22 Oct 2025 20:11:37 +0900, 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.
> 
> 

Applied, thanks!

[1/1] jbd2: allocate lock_class_key for jbd2_handle dynamically
      commit: 524c3853831cf4f7e1db579e487c757c3065165c

Best regards,
-- 
Theodore Ts'o <tytso@mit.edu>

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

Posted by Jan Kara 3 months, 2 weeks ago

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

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

Posted by Tetsuo Handa 3 months, 1 week ago

Who can take this patch?

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
>>
>>

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

Posted by Jan Kara 3 months, 1 week ago

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