From patchwork Fri Jan 12 17:25:53 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Dufour X-Patchwork-Id: 860105 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [103.22.144.68]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3zJ9Gd3WTwz9sBd for ; Sat, 13 Jan 2018 04:48:57 +1100 (AEDT) Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 3zJ9Gd24zPzF0xq for ; Sat, 13 Jan 2018 04:48:57 +1100 (AEDT) X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=linux.vnet.ibm.com (client-ip=148.163.156.1; helo=mx0a-001b2d01.pphosted.com; envelope-from=ldufour@linux.vnet.ibm.com; receiver=) Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (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 3zJ8nG2B8kzF0lN for ; Sat, 13 Jan 2018 04:26:58 +1100 (AEDT) Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w0CHOQ7U094895 for ; Fri, 12 Jan 2018 12:26:55 -0500 Received: from e06smtp15.uk.ibm.com (e06smtp15.uk.ibm.com [195.75.94.111]) by mx0a-001b2d01.pphosted.com with ESMTP id 2ff17p0mpt-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 12 Jan 2018 12:26:55 -0500 Received: from localhost by e06smtp15.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 12 Jan 2018 17:26:51 -0000 Received: from b06cxnps4074.portsmouth.uk.ibm.com (9.149.109.196) by e06smtp15.uk.ibm.com (192.168.101.145) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; Fri, 12 Jan 2018 17:26:43 -0000 Received: from d06av24.portsmouth.uk.ibm.com (mk.ibm.com [9.149.105.60]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w0CHQhAh14614632; Fri, 12 Jan 2018 17:26:43 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E09A042047; Fri, 12 Jan 2018 17:20:15 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E981E42049; Fri, 12 Jan 2018 17:20:13 +0000 (GMT) Received: from nimbus.lab.toulouse-stg.fr.ibm.com (unknown [9.145.191.85]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 12 Jan 2018 17:20:13 +0000 (GMT) From: Laurent Dufour 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 , kemi.wang@intel.com, sergey.senozhatsky.work@gmail.com Subject: [PATCH v6 09/24] mm: Protect SPF handler against anon_vma changes Date: Fri, 12 Jan 2018 18:25:53 +0100 X-Mailer: git-send-email 2.7.4 In-Reply-To: <1515777968-867-1-git-send-email-ldufour@linux.vnet.ibm.com> References: <1515777968-867-1-git-send-email-ldufour@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18011217-0020-0000-0000-000003EA04FC X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18011217-0021-0000-0000-0000427C31A2 Message-Id: <1515777968-867-10-git-send-email-ldufour@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2018-01-12_09:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=2 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1801120238 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.24 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org, npiggin@gmail.com, linux-mm@kvack.org, Tim Chen , haren@linux.vnet.ibm.com, khandual@linux.vnet.ibm.com Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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 22bdc5c6c5ee..3ac54a65b0f9 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -624,7 +624,9 @@ 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)) { @@ -638,7 +640,9 @@ 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,