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 B55176B0003 for ; Mon, 2 Jul 2018 08:26:20 -0400 (EDT) Received: by mail-wm0-f72.google.com with SMTP id l4-v6so3587515wmc.7 for ; Mon, 02 Jul 2018 05:26:20 -0700 (PDT) Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com. [148.163.158.5]) by mx.google.com with ESMTPS id f137-v6si5547174wmg.24.2018.07.02.05.26.18 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 02 Jul 2018 05:26:19 -0700 (PDT) Received: from pps.filterd (m0098420.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w62COCAl029084 for ; Mon, 2 Jul 2018 08:26:18 -0400 Received: from e06smtp05.uk.ibm.com (e06smtp05.uk.ibm.com [195.75.94.101]) by mx0b-001b2d01.pphosted.com with ESMTP id 2jyjaxv3cx-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 02 Jul 2018 08:26:17 -0400 Received: from localhost by e06smtp05.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 2 Jul 2018 13:26:16 +0100 Subject: Re: [RFC v3 PATCH 5/5] x86: check VM_DEAD flag in page fault References: <1530311985-31251-1-git-send-email-yang.shi@linux.alibaba.com> <1530311985-31251-6-git-send-email-yang.shi@linux.alibaba.com> <84eba553-2e0b-1a90-d543-6b22c1b3c5f8@linux.vnet.ibm.com> <20180702121528.GM19043@dhcp22.suse.cz> From: Laurent Dufour Date: Mon, 2 Jul 2018 14:26:09 +0200 MIME-Version: 1.0 In-Reply-To: <20180702121528.GM19043@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Message-Id: <80406cbd-67f4-ca4c-cd54-aeb305579a72@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Yang Shi , willy@infradead.org, akpm@linux-foundation.org, peterz@infradead.org, mingo@redhat.com, acme@kernel.org, alexander.shishkin@linux.intel.com, jolsa@redhat.com, namhyung@kernel.org, tglx@linutronix.de, hpa@zytor.com, linux-mm@kvack.org, x86@kernel.org, linux-kernel@vger.kernel.org On 02/07/2018 14:15, Michal Hocko wrote: > On Mon 02-07-18 10:45:03, Laurent Dufour wrote: >> On 30/06/2018 00:39, Yang Shi wrote: >>> Check VM_DEAD flag of vma in page fault handler, if it is set, trigger >>> SIGSEGV. >>> >>> Cc: Michal Hocko >>> Cc: Thomas Gleixner >>> Cc: Ingo Molnar >>> Cc: "H. Peter Anvin" >>> Signed-off-by: Yang Shi >>> --- >>> arch/x86/mm/fault.c | 4 ++++ >>> 1 file changed, 4 insertions(+) >>> >>> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c >>> index 9a84a0d..3fd2da5 100644 >>> --- a/arch/x86/mm/fault.c >>> +++ b/arch/x86/mm/fault.c >>> @@ -1357,6 +1357,10 @@ static inline bool smap_violation(int error_code, struct pt_regs *regs) >>> bad_area(regs, error_code, address); >>> return; >>> } >>> + if (unlikely(vma->vm_flags & VM_DEAD)) { >>> + bad_area(regs, error_code, address); >>> + return; >>> + } >> >> This will have to be done for all the supported architectures, what about doing >> this check in handle_mm_fault() and return VM_FAULT_SIGSEGV ? > > We already do have a model for that. Have a look at MMF_UNSTABLE. MMF_UNSTABLE is a mm's flag, here this is a VMA's flag which is checked.