linux-kernel - Re: [PATCH] arm64/mm: Remove add_huge_page

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20200506071927.GB7021@willie-the-truck>
Date:   Wed, 6 May 2020 08:19:27 +0100
From:   Will Deacon <will@...nel.org>
To:     Anshuman Khandual <anshuman.khandual@....com>
Cc:     Gavin Shan <gshan@...hat.com>,
        linux-arm-kernel@...ts.infradead.org, mark.rutland@....com,
        catalin.marinas@....com, linux-kernel@...r.kernel.org,
        shan.gavin@...il.com
Subject: Re: [PATCH] arm64/mm: Remove add_huge_page_size()

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@...hat.com>
> > ---
> >  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.

> 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.

Will