Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932564AbbGPBcH (ORCPT ); Wed, 15 Jul 2015 21:32:07 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:56082 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932066AbbGPBL2 (ORCPT ); Wed, 15 Jul 2015 21:11:28 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Christoffer Dall , Catalin Marinas , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 182/251] arm64: Don't report clear pmds and puds as huge Date: Wed, 15 Jul 2015 18:08:23 -0700 Message-Id: <1437008972-9140-183-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1437008972-9140-1-git-send-email-kamal@canonical.com> References: <1437008972-9140-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2004 Lines: 56 3.19.8-ckt4 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Christoffer Dall commit fd28f5d439fca77348c129d5b73043a56f8a0296 upstream. The current pmd_huge() and pud_huge() functions simply check if the table bit is not set and reports the entries as huge in that case. This is counter-intuitive as a clear pmd/pud cannot also be a huge pmd/pud, and it is inconsistent with at least arm and x86. To prevent others from making the same mistake as me in looking at code that calls these functions and to fix an issue with KVM on arm64 that causes memory corruption due to incorrect page reference counting resulting from this mistake, let's change the behavior. Signed-off-by: Christoffer Dall Reviewed-by: Steve Capper Acked-by: Marc Zyngier Fixes: 084bd29810a5 ("ARM64: mm: HugeTLB support.") Signed-off-by: Catalin Marinas Signed-off-by: Kamal Mostafa --- arch/arm64/mm/hugetlbpage.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) 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 -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/