Re: [PATCH v2 01/11] hugetlb: set hugetlb page flag before optimizing vmemmap

[Matthew Wilcox]

On Tue, Sep 05, 2023 at 02:44:00PM -0700, Mike Kravetz wrote:
> @@ -456,6 +457,7 @@ int hugetlb_vmemmap_restore(const struct hstate *h, struct page *head)
>  	unsigned long vmemmap_start = (unsigned long)head, vmemmap_end;
>  	unsigned long vmemmap_reuse;
>  
> +	VM_WARN_ON_ONCE(!PageHuge(head));
>  	if (!HPageVmemmapOptimized(head))
>  		return 0;
>  
> @@ -550,6 +552,7 @@ void hugetlb_vmemmap_optimize(const struct hstate *h, struct page *head)
>  	unsigned long vmemmap_start = (unsigned long)head, vmemmap_end;
>  	unsigned long vmemmap_reuse;
>  
> +	VM_WARN_ON_ONCE(!PageHuge(head));
>  	if (!vmemmap_should_optimize(h, head))
>  		return;

Someone who's looking for an easy patch or three should convert both
of these functions to take a folio instead of a page.  All callers
pass &folio->page.  Obviously do that work on top of Mike's patch set
to avoid creating more work for him.