From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f70.google.com (mail-pg0-f70.google.com [74.125.83.70]) by kanga.kvack.org (Postfix) with ESMTP id 51EFF6B025F for ; Fri, 18 Aug 2017 07:20:23 -0400 (EDT) Received: by mail-pg0-f70.google.com with SMTP id 123so165036560pga.5 for ; Fri, 18 Aug 2017 04:20:23 -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 b14si3694806pll.905.2017.08.18.04.20.21 for ; Fri, 18 Aug 2017 04:20:22 -0700 (PDT) Date: Fri, 18 Aug 2017 12:20:16 +0100 From: Catalin Marinas Subject: Re: [PATCH v6 5/9] arm64: hugetlb: Handle swap entries in huge_pte_offset() for contiguous hugepages Message-ID: <20170818112015.2cvkb7y3gkozz5ip@armageddon.cambridge.arm.com> References: <20170810170906.30772-1-punit.agrawal@arm.com> <20170810170906.30772-6-punit.agrawal@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170810170906.30772-6-punit.agrawal@arm.com> Sender: owner-linux-mm@kvack.org List-ID: To: Punit Agrawal Cc: will.deacon@arm.com, mark.rutland@arm.com, David Woods , steve.capper@arm.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org On Thu, Aug 10, 2017 at 06:09:02PM +0100, Punit Agrawal wrote: > diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c > index d3a6713048a2..09e79785c019 100644 > --- a/arch/arm64/mm/hugetlbpage.c > +++ b/arch/arm64/mm/hugetlbpage.c > @@ -210,6 +210,7 @@ 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); > @@ -217,19 +218,29 @@ pte_t *huge_pte_offset(struct mm_struct *mm, > return NULL; > > pud = pud_offset(pgd, addr); > - if (pud_none(*pud)) > + if (pud_none(*pud) && sz != PUD_SIZE) > return NULL; > /* swap or huge page */ > if (!pud_present(*pud) || pud_huge(*pud)) > return (pte_t *)pud; > /* table; check the next level */ So if sz == PUD_SIZE and we have pud_none(*pud) == true, it returns the pud. Isn't this different from what you proposed for the generic huge_pte_offset()? [1] > > + if (sz == CONT_PMD_SIZE) > + addr &= CONT_PMD_MASK; > + > pmd = pmd_offset(pud, addr); > - if (pmd_none(*pmd)) > + if (pmd_none(*pmd) && > + !(sz == PMD_SIZE || sz == CONT_PMD_SIZE)) > return NULL; Again, if sz == PMD_SIZE, you no longer return NULL. The generic proposal in [1] looks like: if (pmd_none(*pmd)) return NULL; and that's even when sz == PMD_SIZE. Anyway, I think we need to push for [1] again to be accepted before we go ahead with these changes. [1] http://lkml.kernel.org/r/20170725154114.24131-2-punit.agrawal@arm.com -- Catalin -- 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