Re: [PATCH] mm/page_alloc: free allocated PFNs if the range does not match

[David Hildenbrand (Arm)]

On 6/30/26 09:44, Vlastimil Babka (SUSE) wrote:
> On 6/30/26 03:35, Zi Yan wrote:
>> When using __GFP_COMP in alloc_contig_frozen_range(), if the allocated
>> range does not match the requested one, the code errors out with EINVAL
>> without freeing the allocated PFNs and causes free page leaks. Fix it by
>> calling release_free_list() in the error path.
>>
>> The issue is reported by Sashiko[1].
> 
> So this?
> Reported-by: Sashiko <sashiko-bot@xxxxxxxxxx>
> 
>> Fixes: e98337d11bbd ("mm/contig_alloc: support __GFP_COMP")
>> Link: https://sashiko.dev/#/patchset/20260628-keep-subpage-private-zero-at-free-v1-0-f4ce3930d10f@xxxxxxxxxx [1]
>> Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
>> Cc: stable@xxxxxxxxxxxxxxx
> 
> Hm well, it's a path that warns, can only happen due to a development error?
> Not sure we care about stable then. Anyway.
> 

If someone would run into the WARN we would already be in Fixes: territory.

it's a path that should never be executed. If it does, the real issue must be fixed.

So (a) I don't think this is stable material (b) I am skeptical that this is
even a Fixes and (c) I am wondering whether we should touch this *at all*.

:)

-- 
Cheers,

David