From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751633AbdFGNr0 (ORCPT ); Wed, 7 Jun 2017 09:47:26 -0400 Received: from foss.arm.com ([217.140.101.70]:32934 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751576AbdFGNrZ (ORCPT ); Wed, 7 Jun 2017 09:47:25 -0400 Date: Wed, 7 Jun 2017 14:47:32 +0100 From: Will Deacon To: Punit Agrawal Cc: catalin.marinas@arm.com, tbaicar@codeaurora.org, steve.capper@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, manoj.iyer@canonical.com, David Woods Subject: Re: [PATCH v2 1/3] arm64: hugetlb: Fix huge_pte_offset to return poisoned page table entries Message-ID: <20170607134731.GG30263@arm.com> References: <20170517152336.6052-1-punit.agrawal@arm.com> <20170517152336.6052-2-punit.agrawal@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170517152336.6052-2-punit.agrawal@arm.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 17, 2017 at 04:23:34PM +0100, Punit Agrawal wrote: > When memory failure is enabled, a poisoned hugepage pte is marked as a > swap entry. huge_pte_offset() does not return the poisoned page table > entries when it encounters PUD/PMD hugepages. > > This behaviour of huge_pte_offset() leads to error such as below when > munmap is called on poisoned hugepages. > > [ 344.165544] mm/pgtable-generic.c:33: bad pmd 000000083af00074. > > Fix huge_pte_offset() to return the poisoned pte which is then > appropriately handled by the generic layer code. > > Signed-off-by: Punit Agrawal > Acked-by: Steve Capper > Cc: Catalin Marinas > Cc: David Woods > --- > arch/arm64/include/asm/pgtable.h | 2 +- > arch/arm64/mm/hugetlbpage.c | 29 ++++++++++------------------- > 2 files changed, 11 insertions(+), 20 deletions(-) > > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h > index c213fdbd056c..6eae342ced6b 100644 > --- a/arch/arm64/include/asm/pgtable.h > +++ b/arch/arm64/include/asm/pgtable.h > @@ -441,7 +441,7 @@ static inline phys_addr_t pmd_page_paddr(pmd_t pmd) > > #define pud_none(pud) (!pud_val(pud)) > #define pud_bad(pud) (!(pud_val(pud) & PUD_TABLE_BIT)) > -#define pud_present(pud) (pud_val(pud)) > +#define pud_present(pud) pte_present(pud_pte(pud)) > > static inline void set_pud(pud_t *pudp, pud_t pud) > { > diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c > index 7514a000e361..69b8200b1cfd 100644 > --- 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; > + /* table; check the next level */ > + > pmd = pmd_offset(pud, addr); > - if (!pmd_present(*pmd)) > + if (pmd_none(*pmd)) > return NULL; > - > - if (pte_cont(pmd_pte(*pmd))) { > - pmd = pmd_offset( > - pud, (addr & CONT_PMD_MASK)); > - return (pte_t *)pmd; > - } > - if (pmd_huge(*pmd)) > + if (!pmd_present(*pmd) || pmd_huge(*pmd)) Similarly here. Will