Re: [PATCH 1/3] mm/mseal: remove superfluous comments, fix confusion around mm

[Lorenzo Stoakes (ARM)]

On Fri, Jul 17, 2026 at 11:33:13AM +0100, David Hildenbrand (Arm) wrote:
> On 7/16/26 15:43, Lorenzo Stoakes (ARM) wrote:
> > Remove comment blocks that don't add value and eliminate any confusion
> > about whether or not we permit mseal()'ing of remote mm's by explicitly
> > referencing current->mm consistently.
> >
> > Also avoid ugly goto by using an else branch.
> >
> > No functional change intended.
> >
> > Signed-off-by: Lorenzo Stoakes (ARM) <ljs@xxxxxxxxxx>
> > ---
> >  mm/mseal.c | 48 ++++++++----------------------------------------
> >  1 file changed, 8 insertions(+), 40 deletions(-)
> >
> > diff --git a/mm/mseal.c b/mm/mseal.c
> > index 9781647483d1..207fea89c61e 100644
> > --- a/mm/mseal.c
> > +++ b/mm/mseal.c
> > @@ -16,28 +16,7 @@
> >  #include <linux/sched.h>
> >  #include "internal.h"
> >
> > -/*
> > - * mseal() disallows an input range which contain unmapped ranges (VMA holes).
> > - *
> > - * It disallows unmapped regions from start to end whether they exist at the
> > - * start, in the middle, or at the end of the range, or any combination thereof.
> > - *
> > - * This is because after sealing a range, there's nothing to stop memory mapping
> > - * of ranges in the remaining gaps later, meaning that the user might then
> > - * wrongly consider the entirety of the mseal()'d range to be sealed when it
> > - * in fact isn't.
> > - */
> > -
> > -/*
> > - * Does the [start, end) range contain any unmapped memory?
> > - *
> > - * We ensure that:
> > - * - start is part of a valid VMA.
> > - * - end is part of a valid VMA.
> > - * - no gap (unallocated memory) exists between start and end.
> > - */
> > -static bool range_contains_unmapped(struct mm_struct *mm,
> > -		unsigned long start, unsigned long end)
> > +static bool range_contains_unmapped(unsigned long start, unsigned long end)
> >  {
> >  	struct vm_area_struct *vma;
> >  	unsigned long prev_end = start;
> > @@ -53,11 +32,10 @@ static bool range_contains_unmapped(struct mm_struct *mm,
> >  	return prev_end < end;
> >  }
> >
> > -static int mseal_apply(struct mm_struct *mm,
> > -		unsigned long start, unsigned long end)
> > +static int mseal_apply(unsigned long start, unsigned long end)
> >  {
> >  	struct vm_area_struct *vma, *prev;
>
> I guess using
>
> struct mm_struct *mm = current->mm;
>
> would reduce the churn?

Ah yeah true, I avoided that pattern in general because of confusion that
arose from it before. Maybe over conservative :) can change on respin.

>
>
> Anyhow
>
> Acked-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>

Thanks!

>
> --
> Cheers,
>
> David

Cheers, Lorenzo