[PATCH] arm64: Don't report clear pmds and puds as huge

[Steve Capper]

On 1 July 2015 at 14:28, Catalin Marinas <catalin.marinas at arm.com> wrote:
> On Wed, Jul 01, 2015 at 02:18:31PM +0100, Catalin Marinas wrote:
>> On Wed, Jul 01, 2015 at 02:08:31PM +0200, Christoffer Dall wrote:
>> > diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
>> > index 2de9d2e..0eeb4f09 100644
>> > --- a/arch/arm64/mm/hugetlbpage.c
>> > +++ b/arch/arm64/mm/hugetlbpage.c
>> > @@ -40,13 +40,13 @@ int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
>> >
>> >  int pmd_huge(pmd_t pmd)
>> >  {
>> > -   return !(pmd_val(pmd) & PMD_TABLE_BIT);
>> > +   return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
>> >  }
>> >
>> >  int pud_huge(pud_t pud)
>> >  {
>> >  #ifndef __PAGETABLE_PMD_FOLDED
>> > -   return !(pud_val(pud) & PUD_TABLE_BIT);
>> > +   return pud_val(pud) && !(pud_val(pud) & PUD_TABLE_BIT);
>> >  #else
>> >     return 0;
>> >  #endif
>>
>> Thanks for the patch, I'll add the acks/reviews and Fixes: tags.
>>
>> (and I think I'll change pmd_val to pmd_present, same for pud; no
>> functional difference)
>
> A related question - can we ever have PROT_NONE on a huge pmd? I'll
> leave this patch with pmd_val for now, it matches pmd_trans_huge().

Yes PROT_NONE can be used. I have a test case for it in libhugetlbfs
(for HugeTLB) and for THP at:
https://git.linaro.org/people/steve.capper/memory-tests.git

They worked last time I touched them ;-).

Cheers,
--
Steve

>
> --
> Catalin