Re: [PATCH 1/3] mm: introduce VM_MAYBE_GUARD and make visible for guard regions

[Randy Dunlap]

On 10/29/25 9:50 AM, Lorenzo Stoakes wrote:

> diff --git a/mm/memory.c b/mm/memory.c
> index 4c3a7e09a159..a2c79ee43d68 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1478,6 +1478,10 @@ vma_needs_copy(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
>  	if (src_vma->anon_vma)
>  		return true;
>  
> +	/* Guard regions have momdified page tables that require copying. */

	                      modified

> +	if (src_vma->vm_flags & VM_MAYBE_GUARD)
> +		return true;
> +
>  	/*
>  	 * Don't copy ptes where a page fault will fill them correctly.  Fork
>  	 * becomes much lighter when there are big shared or private readonly
-- 
~Randy