Re: [PATCH] mm/migrate_device: fix double unlock

[David Hildenbrand (Arm)]

On 4/13/26 23:15, Sunny Patel wrote:
> migrate_vma_collect_huge_pmd() calls spin_unlock(ptl) after
> softleaf_entry_wait_on_locked(), which already releases the ptl.
> 
> Fixes: a30b48bf1b24 ("mm/migrate_device: implement THP migration of zone device pages")
> 
> Cc: stable@xxxxxxxxxxxxxxx
> 
> Signed-off-by: Sunny Patel <nueralspacetech@xxxxxxxxx>
> ---
>  mm/migrate_device.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/mm/migrate_device.c b/mm/migrate_device.c
> index 8079676c8f1f..7eb2f87ea39d 100644
> --- a/mm/migrate_device.c
> +++ b/mm/migrate_device.c
> @@ -177,7 +177,6 @@ static int migrate_vma_collect_huge_pmd(pmd_t *pmdp, unsigned long start,
>  
>  		if (softleaf_is_migration(entry)) {
>  			softleaf_entry_wait_on_locked(entry, ptl);
> -			spin_unlock(ptl);
>  			return -EAGAIN;
>  		}
>  

As raised by Matthew, the entire code block is dead code:

https://lore.kernel.org/linux-mm/20260212014611.416695-1-dave@xxxxxxxxxxxx/

And I even Ack'ed it /facepalm

So we should take that (cleanup) patch instead. Thanks!

-- 
Cheers,

David