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=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 5BF44C41514 for ; Tue, 20 Aug 2019 13:19:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2812E214DA for ; Tue, 20 Aug 2019 13:19:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="hHhcOFSN"; dkim=pass (1024-bit key) header.d=fb.onmicrosoft.com header.i=@fb.onmicrosoft.com header.b="QH+Jcg4d" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730055AbfHTNTa (ORCPT ); Tue, 20 Aug 2019 09:19:30 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:62898 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729639AbfHTNT3 (ORCPT ); Tue, 20 Aug 2019 09:19:29 -0400 Received: from pps.filterd (m0109331.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x7KDHVF8023693; Tue, 20 Aug 2019 06:19:12 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : references : in-reply-to : content-type : content-id : content-transfer-encoding : mime-version; s=facebook; bh=QSJMSUOkYU2F1gINAGrBbRT6okZp4LOcrVQ0wVrR6s4=; b=hHhcOFSNDEGWB0GgRSGiRrzFoN+kzM2HZLcfG6+NebNm7e7KntFWVbZtN7FB2T/+CJXs PPKO3Sqh1ZzZkHv10dgv2FgV5gYWWslu38/oeE46bIybnQNaNZ4U7oWhPFbthHtdy5Lv HZSbulp0UXQi2pL7t+cSDzrwh0815Khhwvg= Received: from mail.thefacebook.com (mailout.thefacebook.com [199.201.64.23]) by mx0a-00082601.pphosted.com with ESMTP id 2ugc4xs9d4-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-SHA384 bits=256 verify=NOT); Tue, 20 Aug 2019 06:19:12 -0700 Received: from prn-hub03.TheFacebook.com (2620:10d:c081:35::127) by prn-hub04.TheFacebook.com (2620:10d:c081:35::128) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.1.1713.5; Tue, 20 Aug 2019 06:19:10 -0700 Received: from NAM03-DM3-obe.outbound.protection.outlook.com (192.168.54.28) by o365-in.thefacebook.com (192.168.16.27) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.1.1713.5 via Frontend Transport; Tue, 20 Aug 2019 06:19:10 -0700 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=i4mttKsolIUA7YSKPmSTzR3DOut9AneLrH6PS/LvMoSUfkY+qCWQNCyGoKAwROJZLBKEnmXcBVrI8wSZVvi7RayGMZ8fmQQyogNzKPI910z2nqqDzJOqTbngf1208Ek3Y9qvbLJHDj0V7vqihlg3jnzLBH55yBLTE5AQffdXMOECyp2y7zV0+rTmbfcxmnALOX5PAg3M8i/RlFAtfdZj4qAKcJkZwwOkV3km+VGVMOlmThHWQZwx4h+L5dZ1wDyZDpXRoQ5+Hr3Lx5RSb0ETWdqlm0b3eOdcf/uLAFDja53U1Ol9JHju9PH1JDXTaBdwypwzDpzugxro1UIoPctsLw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=QSJMSUOkYU2F1gINAGrBbRT6okZp4LOcrVQ0wVrR6s4=; b=DZwDeOHq4e86zTCd0M4HG/sppfwXkHBjEtegCElSpvsOkc+XBgmSoGS5qLnNXw/DGNLViNbyQHHoXY43jZ1Yi3khsjNVIpwRuobnlFxJPOn+D1rrjgu0SnBjbRhpb1+3XAfvoWn8ienv7t9mLc5OcsPd9fqQ6m0PkKcz2VtfWrZbKhXtSgrVx2KOaXJv387492bIZHgqdCjf+IJukN5Do4MZJ9bpqyyGIh2zvkF3Yg5m+6GuKXyLqr9D23+WgfaDQ/NawjFyYtfsS4s9SLx9rumTdtXoPXrkNvVFZ2pBPLkBIrMZgzZ2rg3ybIF96rv/Dwy1WsFK8WVvnPUqTGKiMA== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=fb.com; dmarc=pass action=none header.from=fb.com; dkim=pass header.d=fb.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.onmicrosoft.com; s=selector2-fb-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=QSJMSUOkYU2F1gINAGrBbRT6okZp4LOcrVQ0wVrR6s4=; b=QH+Jcg4dYfnkNerFjRUXsnIvtswpt0R02GU2AE5u8ZqX90GSaJL9c0Dv6nmA5l3pY9syL4ESVCQM2rkQOtYd6jqxAe5sg6/3mix2fK9iUDDxQET77IOK61BKDqVV3Y5SjBaImATwfU700OZeooBtH4jUR5Iu6u3/8vEuls7ekA0= Received: from MWHPR15MB1165.namprd15.prod.outlook.com (10.175.3.22) by MWHPR15MB1486.namprd15.prod.outlook.com (10.173.228.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2178.16; Tue, 20 Aug 2019 13:19:08 +0000 Received: from MWHPR15MB1165.namprd15.prod.outlook.com ([fe80::45ee:bc50:acfa:60a5]) by MWHPR15MB1165.namprd15.prod.outlook.com ([fe80::45ee:bc50:acfa:60a5%3]) with mapi id 15.20.2178.018; Tue, 20 Aug 2019 13:19:08 +0000 From: Song Liu To: Peter Zijlstra CC: Linux Kernel Mailing List , "linux-mm@kvack.org" , Kernel Team , "stable@vger.kernel.org" , Joerg Roedel , Thomas Gleixner , Dave Hansen , Andy Lutomirski Subject: Re: [PATCH] x86/mm/pti: in pti_clone_pgtable() don't increase addr by PUD_SIZE Thread-Topic: [PATCH] x86/mm/pti: in pti_clone_pgtable() don't increase addr by PUD_SIZE Thread-Index: AQHVVywgQMe0L9XqWkSJYmnWEvsfracDzfeAgAA3YYA= Date: Tue, 20 Aug 2019 13:19:08 +0000 Message-ID: <8483292E-DAD0-4B75-8EB0-8EBEE3D067BB@fb.com> References: <20190820075128.2912224-1-songliubraving@fb.com> <20190820100055.GI2332@hirez.programming.kicks-ass.net> In-Reply-To: <20190820100055.GI2332@hirez.programming.kicks-ass.net> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-mailer: Apple Mail (2.3445.104.11) x-originating-ip: [2620:10d:c090:180::f412] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 74027684-304b-466c-3799-08d72570fb84 x-microsoft-antispam: BCL:0;PCL:0;RULEID:(2390118)(7020095)(4652040)(8989299)(5600148)(711020)(4605104)(1401327)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(2017052603328)(7193020);SRVR:MWHPR15MB1486; x-ms-traffictypediagnostic: MWHPR15MB1486: x-ms-exchange-transport-forked: True x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:6108; x-forefront-prvs: 013568035E x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(396003)(366004)(39860400002)(136003)(346002)(376002)(189003)(199004)(5660300002)(486006)(36756003)(6436002)(8936002)(71200400001)(54906003)(14454004)(71190400001)(2906002)(86362001)(316002)(57306001)(53546011)(6506007)(2616005)(102836004)(53936002)(229853002)(33656002)(99286004)(478600001)(6512007)(8676002)(6116002)(256004)(66946007)(186003)(50226002)(76116006)(81166006)(81156014)(7736002)(25786009)(305945005)(66476007)(66556008)(64756008)(66446008)(4326008)(6916009)(46003)(6246003)(76176011)(476003)(446003)(11346002)(6486002);DIR:OUT;SFP:1102;SCL:1;SRVR:MWHPR15MB1486;H:MWHPR15MB1165.namprd15.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;MX:1;A:1; received-spf: None (protection.outlook.com: fb.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: Nk3s1Mdfd80CqYKy0M7TKhejj55+ILcnFSBIraCI7NX+e/EIfD4yIWhrtpfcKwP+O1NfYlAPXapKJRrjRNy9OBK4Ndw2jRMhPhOIojQZt+BDgNDq89R+AQvK0u/qwbXnCjKfj3QdN1DxNIVjHtHPEAkRRCE6Oye8TD5i5rQXnaHc+R7wyDajpIDnzTx89ToSsft5iLStAC3P6SXmcxGnA5Eeqy87vLGC/QrLyBjMoMsf9oDKsfQ5AtlSekRWaYEfCG0hXbhxMLQ2/BKGD88YKT2wfFlDhtvnXU9CP/i6Lh8Nb1au0sH43tzLQQggN+tDHsAeYb9joTrxA4PkXNuMYg7ETOrHr+QYciNTJJgvfm2LM2YeiNFkZxTQYE2q5eTQgZpRqytguFg1Az5dqndtZyGX11gvdmuwxxOCsVkuq1w= Content-Type: text/plain; charset="us-ascii" Content-ID: <91099288E73293498CB2F2611ECDD1A3@namprd15.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 74027684-304b-466c-3799-08d72570fb84 X-MS-Exchange-CrossTenant-originalarrivaltime: 20 Aug 2019 13:19:08.1341 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: a7SAfubnQCl7/79+PglLPurMUUE0dq1ptZIE6yItatEBaXz9pveH57bDZI+KdIlYysUIfZUphlgpYOSoGCysGw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR15MB1486 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-08-20_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=868 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1908200140 X-FB-Internal: deliver Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Aug 20, 2019, at 3:00 AM, Peter Zijlstra wrote: >=20 > On Tue, Aug 20, 2019 at 12:51:28AM -0700, Song Liu wrote: >> pti_clone_pgtable() increases addr by PUD_SIZE for pud_none(*pud) case. >> This is not accurate because addr may not be PUD_SIZE aligned. >>=20 >> In our x86_64 kernel, pti_clone_pgtable() fails to clone 7 PMDs because >> of this issuse, including PMD for the irq entry table. For a memcache >> like workload, this introduces about 4.5x more iTLB-load and about 2.5x >> more iTLB-load-misses on a Skylake CPU. >>=20 >> This patch fixes this issue by adding PMD_SIZE to addr for pud_none() >> case. >=20 >> diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c >> index b196524759ec..5a67c3015f59 100644 >> --- a/arch/x86/mm/pti.c >> +++ b/arch/x86/mm/pti.c >> @@ -330,7 +330,7 @@ pti_clone_pgtable(unsigned long start, unsigned long= end, >>=20 >> pud =3D pud_offset(p4d, addr); >> if (pud_none(*pud)) { >> - addr +=3D PUD_SIZE; >> + addr +=3D PMD_SIZE; >> continue; >> } >=20 > I'm thinking you're right in that there's a bug here, but I'm also > thinking your patch is both incomplete and broken. >=20 > What that code wants to do is skip to the end of the pud, a pmd_size > increase will not do that. And right below this, there's a second > instance of this exact pattern. >=20 > Did I get the below right? Yes, your are right.=20 Thanks, Song >=20 > --- > diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c > index b196524759ec..32b20b3cb227 100644 > --- a/arch/x86/mm/pti.c > +++ b/arch/x86/mm/pti.c > @@ -330,12 +330,14 @@ pti_clone_pgtable(unsigned long start, unsigned lon= g end, >=20 > pud =3D pud_offset(p4d, addr); > if (pud_none(*pud)) { > + addr &=3D PUD_MASK; > addr +=3D PUD_SIZE; > continue; > } >=20 > pmd =3D pmd_offset(pud, addr); > if (pmd_none(*pmd)) { > + addr &=3D PMD_MASK; > addr +=3D PMD_SIZE; > continue; > }