From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3vR2RZ0xWDzDqD0 for ; Sun, 19 Feb 2017 21:04:25 +1100 (AEDT) Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v1JA3h0L015520 for ; Sun, 19 Feb 2017 05:04:24 -0500 Received: from e31.co.us.ibm.com (e31.co.us.ibm.com [32.97.110.149]) by mx0b-001b2d01.pphosted.com with ESMTP id 28q729uejn-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Sun, 19 Feb 2017 05:04:23 -0500 Received: from localhost by e31.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Sun, 19 Feb 2017 03:04:23 -0700 From: "Aneesh Kumar K.V" To: akpm@linux-foundation.org, Rik van Riel , Mel Gorman , paulus@ozlabs.org, benh@kernel.crashing.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, "Aneesh Kumar K.V" Subject: [PATCH V3 2/3] mm/ksm: Handle protnone saved writes when making page write protect Date: Sun, 19 Feb 2017 15:33:44 +0530 In-Reply-To: <1487498625-10891-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> References: <1487498625-10891-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Message-Id: <1487498625-10891-3-git-send-email-aneesh.kumar@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Without this KSM will consider the page write protected, but a numa fault can later mark the page writable. This can result in memory corruption. Signed-off-by: Aneesh Kumar K.V --- include/asm-generic/pgtable.h | 8 ++++++++ mm/ksm.c | 9 +++++++-- 2 files changed, 15 insertions(+), 2 deletions(-) diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index b6f3a8a4b738..8c8ba48bef0b 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -200,6 +200,10 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres #define pte_mk_savedwrite pte_mkwrite #endif +#ifndef pte_clear_savedwrite +#define pte_clear_savedwrite pte_wrprotect +#endif + #ifndef pmd_savedwrite #define pmd_savedwrite pmd_write #endif @@ -208,6 +212,10 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres #define pmd_mk_savedwrite pmd_mkwrite #endif +#ifndef pmd_clear_savedwrite +#define pmd_clear_savedwrite pmd_wrprotect +#endif + #ifndef __HAVE_ARCH_PMDP_SET_WRPROTECT #ifdef CONFIG_TRANSPARENT_HUGEPAGE static inline void pmdp_set_wrprotect(struct mm_struct *mm, diff --git a/mm/ksm.c b/mm/ksm.c index 9ae6011a41f8..768202831578 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -872,7 +872,8 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page, if (!ptep) goto out_mn; - if (pte_write(*ptep) || pte_dirty(*ptep)) { + if (pte_write(*ptep) || pte_dirty(*ptep) || + (pte_protnone(*ptep) && pte_savedwrite(*ptep))) { pte_t entry; swapped = PageSwapCache(page); @@ -897,7 +898,11 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page, } if (pte_dirty(entry)) set_page_dirty(page); - entry = pte_mkclean(pte_wrprotect(entry)); + + if (pte_protnone(entry)) + entry = pte_mkclean(pte_clear_savedwrite(entry)); + else + entry = pte_mkclean(pte_wrprotect(entry)); set_pte_at_notify(mm, addr, ptep, entry); } *orig_pte = *ptep; -- 2.7.4