From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0206FC433DB for ; Thu, 11 Mar 2021 01:28:27 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6455C64FC1 for ; Thu, 11 Mar 2021 01:28:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6455C64FC1 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=amacapital.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id DA5A78D0260; Wed, 10 Mar 2021 20:28:25 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id D2F758D0250; Wed, 10 Mar 2021 20:28:25 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B818A8D0260; Wed, 10 Mar 2021 20:28:25 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0057.hostedemail.com [216.40.44.57]) by kanga.kvack.org (Postfix) with ESMTP id 99A368D0250 for ; Wed, 10 Mar 2021 20:28:25 -0500 (EST) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 5BB7E1EF1 for ; Thu, 11 Mar 2021 01:28:25 +0000 (UTC) X-FDA: 77905858170.06.3C7E63A Received: from mail-ej1-f45.google.com (mail-ej1-f45.google.com [209.85.218.45]) by imf08.hostedemail.com (Postfix) with ESMTP id EB68E8019140 for ; Thu, 11 Mar 2021 01:28:17 +0000 (UTC) Received: by mail-ej1-f45.google.com with SMTP id c10so42723357ejx.9 for ; Wed, 10 Mar 2021 17:28:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amacapital-net.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=VpOIjQ3p9w0rNFfbAO51HuvtMJp/6aJrl+qPrZuKuR8=; b=aM/wmrMKYr9tu1cwciQttikcxEZH1/v/i+xHpN3cj4QpcL/AU7fKmsWFk9SGeEeUAl XPRFwqreWDxUrqnN+WDqh9pH3udYulUcseEJtij+krUz2w6yLZIBO72w7H/PytPOU0e2 QmAagxnT+PmwAfCzV8VyX8VL3c8FH0PJwrZzjgDMO6vWECa/F3XMyH25193pxJTWq18m 5wejTpNj21k/DNvUX2DyHlQG3osbrPUlZ33s1jbLzrAZZoIR/lydR1HenxDeUjb+wE+U w8P5ha3WaUO7prJow5sGuquFUmLi1UG/i0AyhEw7Hb0HD7XRKP1xbj67OrL0cbUnw6L5 3StQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=VpOIjQ3p9w0rNFfbAO51HuvtMJp/6aJrl+qPrZuKuR8=; b=Y/Y36TurNnT+TG+1+4z3Ecgfv/O/ymajgOm/Onc9ey6rs1UXfjv4L1+22hHhBXVvyq SnxDYlmUZLP23OmxIyPmB2CqKbSU9gJJ+KWAB//0muDaiRw5SkYFguhN2uW02i2AoMcU O50FH/mQzCb1pss+vRAt7RtUeXz/aEN4bdszedJy2aMbN4Yuv0Zl2wszKzlwbiA2YZXj I7kDpgKZNFj3kkjj6EKqsSxageGWvIlizyiX7KRuSwwKdW9P+cdCCqFSIOsY9S+srFle UnnxvyR/SxPyzI7lMZ03cumtNUiSfNgdt6adGamWxz9bulGHUapu4aWXb82IVzQ7BBEh ZpmA== X-Gm-Message-State: AOAM530IKsxx78izyY9uv6BQn9NDGfxcm/L7/mEuPJsQI0vY1oAkRkuR QHAcpJ9miB9pAxCwOBkvBxvBB+VZ2mmyNrU2D5A7Jg== X-Google-Smtp-Source: ABdhPJyzKbaBgpWAEV4KmB44LDkGtgM1yTLos/iUC1Eu7napm28BHmC/ZQK21pLB22uKasKXJZ2WMcH9tvd3gLPonNY= X-Received: by 2002:a17:906:f44:: with SMTP id h4mr663334ejj.204.1615426103622; Wed, 10 Mar 2021 17:28:23 -0800 (PST) MIME-Version: 1.0 References: <4fc1b4e8f1fb4c8c81f280db09178797@intel.com> <047D5B49-FDBB-494C-81E9-DA811476747D@amacapital.net> <20210311091941.45790fcf@alex-virtual-machine> In-Reply-To: <20210311091941.45790fcf@alex-virtual-machine> From: Andy Lutomirski Date: Wed, 10 Mar 2021 17:28:12 -0800 Message-ID: Subject: Re: [PATCH v3] x86/fault: Send a SIGBUS to user process always for hwpoison page access. To: Aili Yao Cc: "Luck, Tony" , Oleg Nesterov , Linux API , Andy Lutomirski , HORIGUCHI NAOYA , Dave Hansen , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , X86 ML , yangfeng1@kingsoft.com, Linux-MM , LKML , sunhao2@kingsoft.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: 5s5szoutqooqxpkgcwuijh6tqtqoadhz X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: EB68E8019140 Received-SPF: none (amacapital.net>: No applicable sender policy available) receiver=imf08; identity=mailfrom; envelope-from=""; helo=mail-ej1-f45.google.com; client-ip=209.85.218.45 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1615426097-685782 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Mar 10, 2021 at 5:19 PM Aili Yao wrote: > > On Mon, 8 Mar 2021 11:00:28 -0800 > Andy Lutomirski wrote: > > > > On Mar 8, 2021, at 10:31 AM, Luck, Tony wrote: > > > > > > =EF=BB=BF > > >> > > >> Can you point me at that SIGBUS code in a current kernel? > > > > > > It is in kill_me_maybe(). mce_vaddr is setup when we disassemble wha= tever get_user() > > > or copy from user variant was in use in the kernel when the poison me= mory was consumed. > > > > > > if (p->mce_vaddr !=3D (void __user *)-1l) { > > > force_sig_mceerr(BUS_MCEERR_AR, p->mce_vaddr, PAGE_SHI= FT); > > > > Hmm. On the one hand, no one has complained yet. On the other hand, har= dware that supports this isn=E2=80=99t exactly common. > > > > We may need some actual ABI design here. We also need to make sure that= things like io_uring accesses or, more generally, anything using the use_m= m / use_temporary_mm ends up either sending no signal or sending a signal t= o the right target. > > > > > > > > Would it be any better if we used the BUS_MCEERR_AO code that goes in= to siginfo? > > > > Dunno. > > I have one thought here but don't know if it's proper: > > Previous patch use force_sig_mceerr to the user process for such a scenar= io; with this method > The SIGBUS can't be ignored as force_sig_mceerr() was designed to. > > If the user process don't want this signal, will it set signal config to = ignore? > Maybe we can use a send_sig_mceerr() instead of force_sig_mceerr(), if pr= ocess want to > ignore the SIGBUS, then it will ignore that, or it can also process the S= IGBUS? I don't think the signal blocking mechanism makes sense for this. Blocking a signal is for saying that, if another process sends the signal (or an async event like ctrl-C), then the process doesn't want it. Blocking doesn't block synchronous things like faults. I think we need to at least fix the existing bug before we add more signals. AFAICS the MCE_IN_KERNEL_COPYIN code is busted for kernel threads. --Andy