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

[Andrew Morton]

On Mon, 29 Jun 2026 21:35:33 -0400 Zi Yan <ziy@xxxxxxxxxx> 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].
> 
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -88,7 +88,7 @@ static struct page *mark_allocated_noprof(struct page *page, unsigned int order,
>  }
>  #define mark_allocated(...)	alloc_hooks(mark_allocated_noprof(__VA_ARGS__))
>  
> -static unsigned long release_free_list(struct list_head *freepages)
> +unsigned long release_free_list(struct list_head *freepages)
>  {
>  	int order;
>  	unsigned long high_pfn = 0;
>
> ...
>
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -7235,9 +7235,11 @@ int alloc_contig_frozen_range_noprof(unsigned long start, unsigned long end,
>  		check_new_pages(head, order);
>  		prep_new_page(head, order, gfp_mask, 0);
>  	} else {
> +		release_free_list(cc.freepages);

I wonder if there's a Kconfig combination which results in this being
undefined.

I couldn't immediately find such a combination.  No doubt we'll be told
if there is one ;)