Messages in this thread | | | Date | Wed, 7 Jun 2017 15:57:16 +0100 | From | Will Deacon <> | Subject | Re: [PATCH v2 1/3] arm64: hugetlb: Fix huge_pte_offset to return poisoned page table entries |
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On Wed, Jun 07, 2017 at 03:30:37PM +0100, Catalin Marinas wrote: > On Wed, Jun 07, 2017 at 02:47:32PM +0100, Will Deacon wrote: > > On Wed, May 17, 2017 at 04:23:34PM +0100, Punit Agrawal wrote: > > > --- a/arch/arm64/mm/hugetlbpage.c > > > +++ b/arch/arm64/mm/hugetlbpage.c > > > @@ -136,36 +136,27 @@ pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr) > > > { > > > pgd_t *pgd; > > > pud_t *pud; > > > - pmd_t *pmd = NULL; > > > - pte_t *pte = NULL; > > > + pmd_t *pmd; > > > > > > pgd = pgd_offset(mm, addr); > > > pr_debug("%s: addr:0x%lx pgd:%p\n", __func__, addr, pgd); > > > if (!pgd_present(*pgd)) > > > return NULL; > > > + > > > pud = pud_offset(pgd, addr); > > > - if (!pud_present(*pud)) > > > + if (pud_none(*pud)) > > > return NULL; > > > > Do you actually need this special case? > > > > > - > > > - if (pud_huge(*pud)) > > > + /* swap or huge page */ > > > + if (!pud_present(*pud) || pud_huge(*pud)) > > > > ... couldn't you just add a '|| pud_none(*pud)' in here? > > > > > return (pte_t *)pud; > > But then you no longer return NULL if *pud == 0.
Does that actually matter? The bits of hugetlb code I looked at will deferenced the returned pud and handle the huge_pte_none case correctly.
Will
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