Re: [PATCH v3] ext4: fix circular lock dependency in ext4_ext_migrate

[Theodore Ts'o]

On Fri, 12 Jun 2026 08:53:30 +0800, Yun Zhou wrote:
> Move iput(tmp_inode) after ext4_writepages_up_write() to avoid a
> circular lock dependency between s_writepages_rwsem and sb_internal
> (freeze protection).
> 
> The deadlock scenario:
> 
>   CPU0 (EXT4_IOC_MIGRATE)        CPU1 (orphan cleanup during mount)
>   ----                           ----
>   ext4_ext_migrate()
>     ext4_writepages_down_write()
>       s_writepages_rwsem (write)
>                                  ext4_evict_inode()
>                                    sb_start_intwrite()   [sb_internal]
>                                    ...
>                                      ext4_writepages()
>                                        s_writepages_rwsem (read) [BLOCKED]
>     iput(tmp_inode)
>       ext4_evict_inode()
>         sb_start_intwrite()         [BLOCKED]
> 
> [...]

Applied, thanks!

[1/1] ext4: fix circular lock dependency in ext4_ext_migrate
      commit: a897682793eba5de51ee6f3152760374afa629cf

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