Re: [PATCH] arm64/mm: Remove add_huge_page_size()

[Gavin Shan]

On 5/6/20 5:19 PM, Will Deacon wrote:
> On Wed, May 06, 2020 at 12:36:43PM +0530, Anshuman Khandual wrote:
> > On 05/06/2020 12:16 PM, Gavin Shan wrote:
> > > The function add_huge_page_size(), wrapper of hugetlb_add_hstate(),
> > > avoids to register duplicated huge page states for same size. However,
> > > the same logic has been included in hugetlb_add_hstate(). So it seems
> > > unnecessary to keep add_huge_page_size() and this just removes it.
> >
> > Makes sense.
> >
> > > Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
> > > ---
> > >   arch/arm64/mm/hugetlbpage.c | 18 +++++-------------
> > >   1 file changed, 5 insertions(+), 13 deletions(-)
> > >
> > > diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> > > index bbeb6a5a6ba6..ed7530413941 100644
> > > --- a/arch/arm64/mm/hugetlbpage.c
> > > +++ b/arch/arm64/mm/hugetlbpage.c
> > > @@ -441,22 +441,14 @@ void huge_ptep_clear_flush(struct vm_area_struct *vma,
> > >   	clear_flush(vma->vm_mm, addr, ptep, pgsize, ncontig);
> > >   }
> > >   
> > > -static void __init add_huge_page_size(unsigned long size)
> > > -{
> > > -	if (size_to_hstate(size))
> > > -		return;
> > > -
> > > -	hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT);
> > > -}
> > > -
> > >   static int __init hugetlbpage_init(void)
> > >   {
> > >   #ifdef CONFIG_ARM64_4K_PAGES
> > > -	add_huge_page_size(PUD_SIZE);
> > > +	hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
> > >   #endif
> > > -	add_huge_page_size(CONT_PMD_SIZE);
> > > -	add_huge_page_size(PMD_SIZE);
> > > -	add_huge_page_size(CONT_PTE_SIZE);
> > > +	hugetlb_add_hstate(CONT_PMD_SHIFT + PMD_SHIFT - PAGE_SHIFT);
> > > +	hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
> > > +	hugetlb_add_hstate(CONT_PTE_SHIFT);
>
> Something similar has already been done in linux-next.

Thanks, Will. I didn't check linux-next before posting this patch.
Please ignore it then :)

> > Should these page order values be converted into macros instead. Also
> > we should probably keep (CONT_PTE_SHIFT + PAGE_SHIFT - PAGE_SHIFT) as
> > is to make things more clear.
>
> I think the real confusion stems from us not being consistent with your
> *_SHIFT definitions on arm64. It's madness for CONT_PTE_SHIFT to be smaller
> than PAGE_SHIFT imo, but it's just cosmetic I guess.

Yeah, Do you want me to post a patch, to fix it?

> Will

Thanks,
Gavin