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

[Balbir Singh <balbirs@nvidia.com>]

On 4/14/26 20:03, David Hildenbrand (Arm) wrote:
> 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@vger.kernel.org
>>
>> Signed-off-by: Sunny Patel <nueralspacetech@gmail.com>
>> ---
>>  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@stgolabs.net/
> 
> And I even Ack'ed it /facepalm
> 
> So we should take that (cleanup) patch instead. Thanks!
> 

+1

Balbir