From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f72.google.com (mail-wm0-f72.google.com [74.125.82.72]) by kanga.kvack.org (Postfix) with ESMTP id CBDF56B026E for ; Mon, 9 Oct 2017 06:08:52 -0400 (EDT) Received: by mail-wm0-f72.google.com with SMTP id i124so24114942wmf.7 for ; Mon, 09 Oct 2017 03:08:52 -0700 (PDT) Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com. [148.163.158.5]) by mx.google.com with ESMTPS id w54si253675edw.59.2017.10.09.03.08.51 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 09 Oct 2017 03:08:51 -0700 (PDT) Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v99A8okB096883 for ; Mon, 9 Oct 2017 06:08:50 -0400 Received: from e06smtp13.uk.ibm.com (e06smtp13.uk.ibm.com [195.75.94.109]) by mx0a-001b2d01.pphosted.com with ESMTP id 2dg4cdy8nu-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 09 Oct 2017 06:08:49 -0400 Received: from localhost by e06smtp13.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 9 Oct 2017 11:08:29 +0100 From: Laurent Dufour Subject: [PATCH v4 08/20] mm: Protect SPF handler against anon_vma changes Date: Mon, 9 Oct 2017 12:07:40 +0200 In-Reply-To: <1507543672-25821-1-git-send-email-ldufour@linux.vnet.ibm.com> References: <1507543672-25821-1-git-send-email-ldufour@linux.vnet.ibm.com> Message-Id: <1507543672-25821-9-git-send-email-ldufour@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: paulmck@linux.vnet.ibm.com, peterz@infradead.org, akpm@linux-foundation.org, kirill@shutemov.name, ak@linux.intel.com, mhocko@kernel.org, dave@stgolabs.net, jack@suse.cz, Matthew Wilcox , benh@kernel.crashing.org, mpe@ellerman.id.au, paulus@samba.org, Thomas Gleixner , Ingo Molnar , hpa@zytor.com, Will Deacon , Sergey Senozhatsky , Andrea Arcangeli , Alexei Starovoitov Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, haren@linux.vnet.ibm.com, khandual@linux.vnet.ibm.com, npiggin@gmail.com, bsingharora@gmail.com, Tim Chen , linuxppc-dev@lists.ozlabs.org, x86@kernel.org The speculative page fault handler must be protected against anon_vma changes. This is because page_add_new_anon_rmap() is called during the speculative path. In addition, don't try speculative page fault if the VMA don't have an anon_vma structure allocated because its allocation should be protected by the mmap_sem. In __vma_adjust() when importer->anon_vma is set, there is no need to protect against speculative page faults since speculative page fault is aborted if the vma->anon_vma is not set. When calling page_add_new_anon_rmap() vma->anon_vma is necessarily valid since we checked for it when locking the pte and the anon_vma is removed once the pte is unlocked. So even if the speculative page fault handler is running concurrently with do_unmap(), as the pte is locked in unmap_region() - through unmap_vmas() - and the anon_vma unlinked later, because we check for the vma sequence counter which is updated in unmap_page_range() before locking the pte, and then in free_pgtables() so when locking the pte the change will be detected. Signed-off-by: Laurent Dufour --- mm/memory.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/memory.c b/mm/memory.c index 65cd35b5d0c0..d972ef4e3151 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -618,7 +618,9 @@ void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma, * Hide vma from rmap and truncate_pagecache before freeing * pgtables */ + vm_write_begin(vma); unlink_anon_vmas(vma); + vm_write_end(vma); unlink_file_vma(vma); if (is_vm_hugetlb_page(vma)) { @@ -632,7 +634,9 @@ void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma, && !is_vm_hugetlb_page(next)) { vma = next; next = vma->vm_next; + vm_write_begin(vma); unlink_anon_vmas(vma); + vm_write_end(vma); unlink_file_vma(vma); } free_pgd_range(tlb, addr, vma->vm_end, -- 2.7.4 -- 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