Re: [PATCH v2] jbd2: fix deadlock in jbd2_journal_cancel_revoke()

[Theodore Ts'o]

On Thu, 09 Apr 2026 19:42:03 +0800, Zhang Yi wrote:
> Commit f76d4c28a46a ("fs/jbd2: use sleeping version of
> __find_get_block()") changed jbd2_journal_cancel_revoke() to use
> __find_get_block_nonatomic() which holds the folio lock instead of
> i_private_lock. This breaks the lock ordering (folio -> buffer) and
> causes an ABBA deadlock when the filesystem blocksize < pagesize:
> 
>      T1                                T2
> ext4_mkdir()
>  ext4_init_new_dir()
>   ext4_append()
>    ext4_getblk()
>     lock_buffer()    <- A
>                                    sync_blockdev()
>                                     blkdev_writepages()
>                                      writeback_iter()
>                                       writeback_get_folio()
>                                        folio_lock()   <- B
>      ext4_journal_get_create_access()
>       jbd2_journal_cancel_revoke()
>        __find_get_block_nonatomic()
>         folio_lock()  <- B
>                                      block_write_full_folio()
>                                       lock_buffer()   <- A
> 
> [...]

Applied, thanks!

[1/1] jbd2: fix deadlock in jbd2_journal_cancel_revoke()
      commit: 981fcc5674e67158d24d23e841523eccba19d0e7

Best regards,
-- 
Theodore Ts'o <tytso@xxxxxxx>