linux-kernel - Re: [PATCH v2 2/3] hugetlb: Convert hugetlb_no_page() to use struct vm

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Date: Thu, 4 Apr 2024 12:58:17 -0700
From: Vishal Moola <vishal.moola@...il.com>
To: Oscar Salvador <osalvador@...e.de>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
	akpm@...ux-foundation.org, muchun.song@...ux.dev, willy@...radead.org
Subject: Re: [PATCH v2 2/3] hugetlb: Convert hugetlb_no_page() to use struct vm_fault

On Thu, Apr 4, 2024 at 5:49 AM Oscar Salvador <osalvador@...e.de> wrote:
>
> On Mon, Apr 01, 2024 at 01:26:50PM -0700, Vishal Moola (Oracle) wrote:
> > hugetlb_no_page() can use the struct vm_fault passed in from
> > hugetlb_fault(). This alleviates the stack by consolidating 7
> > variables into a single struct.
> >
> > Signed-off-by: Vishal Moola (Oracle) <vishal.moola@...il.com>
> > ---
> >  mm/hugetlb.c | 59 ++++++++++++++++++++++++++--------------------------
> >  1 file changed, 29 insertions(+), 30 deletions(-)
> >
> > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> > index 360b82374a89..aca2f11b4138 100644
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -6189,9 +6189,7 @@ static bool hugetlb_pte_stable(struct hstate *h, struct mm_struct *mm,
> >
> >  static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
> >                       struct vm_area_struct *vma,
> > -                     struct address_space *mapping, pgoff_t idx,
> > -                     unsigned long address, pte_t *ptep,
> > -                     pte_t old_pte, unsigned int flags,
> > +                     struct address_space *mapping,
>
> AFAICS all this can be self-contained in vm_fault struct.
> vmf->vma->mm and vmf->vma.
> I mean, if we want to convert this interface, why not going all the way?
>
> Looks a bit odd some fields yes while some others remain.
>
> Or am I missing something?

Mainly just minimizing code churn, we would either unnecessarily
change multiple lines using vma or have to declare the variables
again anyways (or have extra churn I didn't like).