Re: [PATCH mm-hotfixes] mm/mseal: update VMA end correctly on merge

["Lorenzo Stoakes (Oracle)" <ljs@kernel.org>]

On Fri, Mar 27, 2026 at 08:24:46AM -0700, Andrew Morton wrote:
> On Fri, 27 Mar 2026 09:06:40 +0000 "Lorenzo Stoakes (Oracle)" <ljs@kernel.org> wrote:
>
> > --- a/mm/mseal.c
> > +++ b/mm/mseal.c
> > @@ -66,7 +66,7 @@ static int mseal_apply(struct mm_struct *mm,
> >  		prev = vma;
> >
> >  	for_each_vma_range(vmi, vma, end) {
> > -		const unsigned long curr_end = MIN(vma->vm_end, end);
> > +		unsigned long curr_end = MIN(vma->vm_end, end);
> >
> >  		if (!(vma->vm_flags & VM_SEALED)) {
> >  			vm_flags_t vm_flags = vma->vm_flags | VM_SEALED;
> > @@ -76,6 +76,7 @@ static int mseal_apply(struct mm_struct *mm,
> >  			if (IS_ERR(vma))
> >  				return PTR_ERR(vma);
> >  			vm_flags_set(vma, VM_SEALED);
> > +			curr_end = vma->vm_end; /* Merge may have updated. */
> >  		}
> >
> >  		prev = vma;
>
> This led to some rework in your "mm/vma: convert
> vma_modify_flags[_uffd]() to use vma_flags_t".  Please check my
> handiwork.
>
> reject:
>
> --- mm/mseal.c~mm-vma-convert-vma_modify_flags-to-use-vma_flags_t
> +++ mm/mseal.c
> @@ -68,14 +68,17 @@ static int mseal_apply(struct mm_struct
>  	for_each_vma_range(vmi, vma, end) {
>  		const unsigned long curr_end = MIN(vma->vm_end, end);
>
> -		if (!(vma->vm_flags & VM_SEALED)) {
> -			vm_flags_t vm_flags = vma->vm_flags | VM_SEALED;
> +		if (!vma_test(vma, VMA_SEALED_BIT)) {
> +			vma_flags_t vma_flags = vma->flags;
> +
> +			vma_flags_set(&vma_flags, VMA_SEALED_BIT);
>
>  			vma = vma_modify_flags(&vmi, prev, vma, curr_start,
> -					       curr_end, &vm_flags);
> +					       curr_end, &vma_flags);
>  			if (IS_ERR(vma))
>  				return PTR_ERR(vma);
> -			vm_flags_set(vma, VM_SEALED);
> +			vma_start_write(vma);
> +			vma_set_flags(vma, VMA_SEALED_BIT);
>  		}
>
>  		prev = vma;
>
> resolution:
>
> static int mseal_apply(struct mm_struct *mm,
> 		unsigned long start, unsigned long end)
> {
> 	struct vm_area_struct *vma, *prev;
> 	unsigned long curr_start = start;
> 	VMA_ITERATOR(vmi, mm, start);
>
> 	/* We know there are no gaps so this will be non-NULL. */
> 	vma = vma_iter_load(&vmi);
> 	prev = vma_prev(&vmi);
> 	if (start > vma->vm_start)
> 		prev = vma;
>
> 	for_each_vma_range(vmi, vma, end) {
> 		unsigned long curr_end = MIN(vma->vm_end, end);
>
> 		if (!vma_test(vma, VMA_SEALED_BIT)) {
> 			vma_flags_t vma_flags = vma->flags;
>
> 			vma_flags_set(&vma_flags, VMA_SEALED_BIT);
>
> 			vma = vma_modify_flags(&vmi, prev, vma, curr_start,
> 					       curr_end, &vma_flags);
> 			if (IS_ERR(vma))
> 				return PTR_ERR(vma);
> 			vma_start_write(vma);
> 			vma_set_flags(vma, VMA_SEALED_BIT);
> 			curr_end = vma->vm_end; /* Merge may have updated. */
> 		}
>
> 		prev = vma;
> 		curr_start = curr_end;
> 	}
>
> 	return 0;
> }
>

Thanks that looks correct!

Cheers, Lorenzo