From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f200.google.com (mail-pf0-f200.google.com [209.85.192.200]) by kanga.kvack.org (Postfix) with ESMTP id 5969B280300 for ; Tue, 22 Aug 2017 10:15:06 -0400 (EDT) Received: by mail-pf0-f200.google.com with SMTP id x137so72664814pfd.14 for ; Tue, 22 Aug 2017 07:15:06 -0700 (PDT) Received: from foss.arm.com (usa-sjc-mx-foss1.foss.arm.com. [217.140.101.70]) by mx.google.com with ESMTP id 71si9014989pfy.79.2017.08.22.07.15.04 for ; Tue, 22 Aug 2017 07:15:04 -0700 (PDT) Subject: Re: [PATCH v7 5/9] arm64: hugetlb: Handle swap entries in huge_pte_offset() for contiguous hugepages References: <20170822104249.2189-1-punit.agrawal@arm.com> <20170822104249.2189-6-punit.agrawal@arm.com> From: Julien Thierry Message-ID: Date: Tue, 22 Aug 2017 15:14:59 +0100 MIME-Version: 1.0 In-Reply-To: <20170822104249.2189-6-punit.agrawal@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Punit Agrawal , will.deacon@arm.com, catalin.marinas@arm.com Cc: mark.rutland@arm.com, David Woods , steve.capper@arm.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org Hi Punit, On 22/08/17 11:42, Punit Agrawal wrote: > huge_pte_offset() was updated to correctly handle swap entries for > hugepages. With the addition of the size parameter, it is now possible > to disambiguate whether the request is for a regular hugepage or a > contiguous hugepage. > > Fix huge_pte_offset() for contiguous hugepages by using the size to find > the correct page table entry. > > Signed-off-by: Punit Agrawal > Cc: David Woods > --- > arch/arm64/mm/hugetlbpage.c | 21 ++++++++++++++++----- > 1 file changed, 16 insertions(+), 5 deletions(-) > > diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c > index 594232598cac..b95e24dc3477 100644 > --- a/arch/arm64/mm/hugetlbpage.c > +++ b/arch/arm64/mm/hugetlbpage.c > @@ -214,6 +214,7 @@ pte_t *huge_pte_offset(struct mm_struct *mm, > pgd_t *pgd; > pud_t *pud; > pmd_t *pmd; > + pte_t *pte; > > pgd = pgd_offset(mm, addr); > pr_debug("%s: addr:0x%lx pgd:%p\n", __func__, addr, pgd); > @@ -221,19 +222,29 @@ pte_t *huge_pte_offset(struct mm_struct *mm, > return NULL; > > pud = pud_offset(pgd, addr); > - if (pud_none(*pud)) > + if (sz != PUD_SIZE && pud_none(*pud)) > return NULL; > - /* swap or huge page */ > - if (!pud_present(*pud) || pud_huge(*pud)) > + /* hugepage or swap? */ > + if (pud_huge(*pud) || !pud_present(*pud)) > return (pte_t *)pud; > /* table; check the next level */ > > + if (sz == CONT_PMD_SIZE) > + addr &= CONT_PMD_MASK; > + > pmd = pmd_offset(pud, addr); > - if (pmd_none(*pmd)) > + if (!(sz == PMD_SIZE || sz == CONT_PMD_SIZE) && > + pmd_none(*pmd)) > return NULL; > - if (!pmd_present(*pmd) || pmd_huge(*pmd)) > + if (pmd_huge(*pmd) || !pmd_present(*pmd)) > return (pte_t *)pmd; > > + if (sz == CONT_PTE_SIZE) { > + pte = pte_offset_kernel( > + pmd, (addr & CONT_PTE_MASK)); > + return pte; Nit: Looks like this is the only place the new variable pte is used. Since we don't need to test its value, why not just write: return pte_offset_kernel(pmd, (addr & CONT_PTE_MASK)); and get rid of the pte variable? Cheers, -- Julien Thierry -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org