From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933479AbcKDD0O (ORCPT ); Thu, 3 Nov 2016 23:26:14 -0400 Received: from mail-db5eur01on0057.outbound.protection.outlook.com ([104.47.2.57]:17875 "EHLO EUR01-DB5-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932909AbcKDD0M (ORCPT ); Thu, 3 Nov 2016 23:26:12 -0400 Authentication-Results: spf=pass (sender IP is 217.140.96.140) smtp.mailfrom=arm.com; lists.infradead.org; dkim=none (message not signed) header.d=none;lists.infradead.org; dmarc=bestguesspass action=none header.from=arm.com; X-IncomingTopHeaderMarker: OriginalChecksum:;UpperCasedChecksum:;SizeAsReceived:1065;Count:14 Date: Fri, 4 Nov 2016 10:52:17 +0800 From: Huang Shijie To: Catalin Marinas CC: , , , , , , , Subject: Re: [PATCH 1/2] arm64: hugetlb: remove the wrong pmd check in find_num_contig() Message-ID: <20161104025216.GA19810@sha-win-210.asiapac.arm.com> References: <1478140059-13829-1-git-send-email-shijie.huang@arm.com> <1478140059-13829-2-git-send-email-shijie.huang@arm.com> <20161104001616.ssjbemliorxi6evl@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20161104001616.ssjbemliorxi6evl@localhost> User-Agent: Mutt/1.7.1 (2016-10-04) X-IncomingHeaderCount: 14 X-EOPAttributedMessage: 0 X-MS-Office365-Filtering-HT: Tenant X-Forefront-Antispam-Report: CIP:217.140.96.140;IPV:CAL;SCL:-1;CTRY:GB;EFV:NLI;SFV:NSPM;SFS:(10009020)(6009001)(7916002)(2980300002)(438002)(24454002)(189002)(199003)(106466001)(626004)(110136003)(2950100002)(47776003)(5660300001)(87936001)(7696004)(4326007)(46406003)(50466002)(83506001)(189998001)(23726003)(246002)(7846002)(104016004)(305945005)(54356999)(586003)(50986999)(76176999)(4001350100001)(1076002)(86362001)(8936002)(356003)(2906002)(92566002)(26826002)(8676002)(97756001)(33656002)(77096005)(6636002)(11100500001)(6666003)(18370500001);DIR:OUT;SFP:1101;SCL:1;SRVR:DB6PR0802MB2566;H:nebula.arm.com;FPR:;SPF:Pass;PTR:fw-tnat.cambridge.arm.com;MX:1;A:1;LANG:en; X-Microsoft-Exchange-Diagnostics: 1;AM1FFO11FD020;1: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 X-MS-Office365-Filtering-Correlation-Id: 3409d658-a1cf-4b0d-360d-08d4045d99ee X-Microsoft-Exchange-Diagnostics: 1;DB6PR0802MB2566;2:QRZu8WnDZai+MAmVYQPd7Idn8kTZOdrUhAa+08TAtwcFPA7uz5Rj9zjeb3bdBVYYs4XBf5q9NYtMMVKKz4N92hq3kiJFBYKZx1ZlTSB1CUW61m1Cz2RBhxo0+ihEd34Db8JskoWrIjD4+48AFUSKC2nTHPgkQ2rXDxmdzgcu0CiPqoJQHEqaVLTqrNl9qoOYWl+ZFf8e4irQmnN5WRkYXg==;3:jghPQMw11B6j6vxjcSVmxjzy5/1ELnrDPBF8BLfCHYWg7yF+iH/av6GCrP4Wflpa72hKrFPFYansoZ9lOJMuFF3CPtNdhCIex5Vys4SFbp5sfXgAqArEsINYmCErg8v4Ms/FBYO5mihyiCkgsml6EE2xjXpnlupcrC1Oii3Fhg5yUWw6QX81pd+hQfRFyPcVZ3GjS97iGXtd1ahq/kzKYa3SDP5mA83yrjOtmVeSvsDlkZCflj02mT+UdWF6InXPICJKx7Fct/wuqZtFUtXRupn4rACFtHhF3mkNj3OxmXY= X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(8251501002);SRVR:DB6PR0802MB2566; X-Microsoft-Exchange-Diagnostics: 1;DB6PR0802MB2566;25:KuxYe2jX7nWdtCFDQOeKRyHGOpl2lzSSAFLSzxgULX7WiUeGy3dXNZled69ixS5b7Ke0IczWJx+SXV4yFJJ2WldUqkurwthTbJJ0tO0yun3ZmlvM9Bo9eS55ZSEwr0JTKHBWK4Myx5DUe9z8UwBUmVOwBDVKhScKs4SAPD45vCdgEQVLXSuIcwU37bVmR+PQmkhWi7zKKHYWeYmdZTiEI49fEgiHk2A2cPHMiRWMoNr4E1W021tfJ0gZXYy+bwsJ8jVOhiNBaaSv+H94j8XJC/U6Bnuv1f0OzlySgJb8jZ0PcWZ6vyZF1Mq2UAk5Zl0bWDjWFDYqxkyFzcHjKqblP8hVRkZeZbWHu4QYn100dNHDQ+djKciEtKe4dXAsRUEpEzwRzWDbleqzEQNTa49PQNrniT4kKF8VXN2pHwgW5hs=;31:iuDFqBpFD2cQVxZxnts4hTiOq+++Uq06mTy2jt/lbWxa/IZppKrS+XXf6Q0knkflWqj3fnez304D6BrFobzKywCPGqT30DGIv5BLSKdWe/hHqaDKcwZkG4XWTYfsEZuzCeHmC3fv1DFDcoNvo4cZucjKamHJRgEXhY7VBAx/MXrfbLUPNDv0vd6r4ugqExIILzKuxq3aJDz49Q5PU1anuzndlM4ShxtsiPXVlfeQArs/ltZKu/Lnd83RwRgZNPityp/alD0yb3mbWbLCx3yuog== NoDisclaimer: True X-Microsoft-Exchange-Diagnostics: 1;DB6PR0802MB2566;20:nXoRKAOuziYDzO73ZTOnpv/fIqb+HlnLNIMmnO/f5AwgXvKO8LiINQLNM+cWrgysKS5eUn1zKiz2QgBSC+GScX9+8ewa0FNf5pd1EI46Q1pIUgI5kckxfhLn9UlubFqPF0qcSIlBxqpLCmkc6DQtXsMYIR0b9lhJiW94Wr4ERR3AgU0jJGs8ksF5ceok5YllZr0P6nXkvJduFLsmNxx3BZLbQYG8LVJZw5BLOMLkiYrsm67vyuTzbpth6tcPcQZw;4: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 X-Microsoft-Antispam-PRVS: X-Exchange-Antispam-Report-Test: UriScan:; X-Exchange-Antispam-Report-CFA-Test: BCL:0;PCL:0;RULEID:(6040176)(601004)(2401047)(8121501046)(13013025)(5005006)(13020025)(13024025)(13023025)(3002001)(10201501046)(6055026);SRVR:DB6PR0802MB2566;BCL:0;PCL:0;RULEID:;SRVR:DB6PR0802MB2566; X-Forefront-PRVS: 01165471DB X-Microsoft-Exchange-Diagnostics: =?us-ascii?Q?1;DB6PR0802MB2566;23:CSdjzqdYtfU5O6xTDYi0cP8tqa90nyrRtH7nrh3?= =?us-ascii?Q?pQZE4KFLJ5at+QAbzVdOscRizF2888rm6m/a9acDUWIhrTMiYzZDmnaSTWd8?= =?us-ascii?Q?RnPrZS/IHAJ2mCSrmQgzEqaezDyB9JPYoMyRxGDeZOBY9N817lfyX9z6ecw9?= =?us-ascii?Q?cLDauArOhzoTB4p0McmAK7yJWLHOK/k7o2gPaN0BPalr5iHYBLs+fv6P+5xJ?= =?us-ascii?Q?Pp4E7+C5yXI0YHDf8edIrUpXuVVLh98l43WJySsZ8vNL92FB+1nBgtzrm1cn?= =?us-ascii?Q?DPpcoEqPtjwXaRegga0czBxyuR2vVUIslq5doZr9sCaqYvnE/O0Rj9Vkx5RU?= =?us-ascii?Q?I7qpWV7QNfGjfIwVo9I91xsgvP6h1TQ2QRQ27dAvWj/DVJC+zePo9A8Ya2AA?= =?us-ascii?Q?1OkYsOpEZGV6A+3/ppaVB+MbXR4Vm33rVcOuVCkC9Hsmfb3uEuTkP0EMpZKp?= =?us-ascii?Q?wxZ9UzdCne7ParL1XGpKq8a7FVYzGoCo/qwBKSqNSqEsUk7N8EH0sjpM6Akc?= =?us-ascii?Q?Ho7n64x8/co265A33HORlVoGD4geOWlAR2RlUnJMHM16Iu00a6ZAS7W5LaXD?= =?us-ascii?Q?Tnz7D72Q7I4T/t33h9EdoE8ME5yYL4p0puCKqcbRG12Z0FEWYtIk/fjNKIHG?= =?us-ascii?Q?3R3qfZButj5lKC9etvFfMHPIL4Nt13fqDEOrbxFawOpaDyzLDuqojGldutRB?= =?us-ascii?Q?Sk612sULdEMu8msH6eUKVIfb9Dr/z58Yc/nSmBdZg5Hj6+9tlyCbvusvOIvE?= =?us-ascii?Q?QKCNXD2AZPd2w/xXlZY0XPhp/1+Hkt9g4Mu5GtZFFm0PAIvKTX2krmnakYS7?= =?us-ascii?Q?zqm++nudWuDPPdrUQmjma80XO+m/JYaf9h8SFUsBBbdxzdrNv/6V7SJddP1+?= =?us-ascii?Q?DrcYhIZ93C+XIC02ciqlgLcLrcBA7Cr1J9BnWS+FIia7VlWIQcgVHCwJbB1L?= =?us-ascii?Q?PzVjwsfbg5nl2PHO83+yLmrYv3KEQE4vlAWNN7JYhxWGS2HnKZvfZPY/xqys?= =?us-ascii?Q?hq+kEM1MowP6CzZ1FE1OdUVyAfkCtmT1KPKPLZ2D4jfT3PTL5yN5SGff4gq7?= =?us-ascii?Q?q6LZqLAx3xNBOWHLTaH4rCxvMrQz7PlRajtZDQsfKiihv+alrPx0zmEnj2IH?= =?us-ascii?Q?15BjdLfJK4mE=3D?= X-Microsoft-Exchange-Diagnostics: 1;DB6PR0802MB2566;6:rVRQyBYfNbh8/srD6f8bLZCneuwKPiRjy5y093l9b6zZG5a0tYVUhDGCvRCelHjI4j5GvJj1snBBK1n2dSfHCuMifQ3vqpSEG2b3/pMjsrfe8GYmhhfIjSbpIMwstm+e+NntSAsRB+xf7ZY6NCXIa4AXj6IgKmo4uVWLtm9UXMfSHI/nOU7Mf+I8UdMZtHz8I7bByFZNKLXQToxwn4Fss/VOZEPNOiePARPl7tOhr62z2oeOpn12vE4nwwB7nx5J1xkyzY7enPJM1wPXQmoWksvs2GQepkJJHCBcoO54InsGXveaxitdx0C7+qfpvexPaDiBo2DB7Atm+RnQCVEofg==;5:cdua0/pfIDDSOY0idPMCv6Ei6qheukDDW4Q4/JpoknVaTjLlw3sI86QAuXc/2MQZ0Ra5m5+bz2zAcLOFZCfFUC0/6LmSkLvJ2kqgLPPeXkPpFVRbfmmZUMKuJUnpxBZcPe7/Lj/GbTGQfMTKBehKH8Aj6fy2JU9fL9rGmWxuEPU=;24:thNpSBnrXI5XMO8O9A6kRBLmOFu1sLMnw/Ch927BsABvhbRmbdq+pqCrtkgK6S/DtsM8ex37clNfE2DxigtclQS1LmXMpePYoSWaw8Vt3UE= SpamDiagnosticOutput: 1:99 SpamDiagnosticMetadata: NSPM X-Microsoft-Exchange-Diagnostics: 1;DB6PR0802MB2566;7:d22DVtULfvg0qilO+23hiL27CMMDQU/+c7IsksaR5FZVdKo+kaTPZmUDAO3vAkiBzQB8b2yT8/Hl2+gNvcKVWPclk+VZTmIDIJKbUcbm5QJyoXWL4RbNLQaQb+HsnxDrwnA4C8eGHa5UQTCCX++mgqGAaXCFM5jhZ+8/z0aa6AaNv3xPR5ozWHcLMjkrFaiWw4r1ZEe6cBdo0/4vdJacoWs0cl8ObPvcVCDKoEugkLuNaysRZHJMpnOZkWlr9IUCGClSZ8Om58aEbgvM+GqEZCn3GeZCwz0K/hmuke/2XQwYcIYc1NJcMX/Z4PgKyUct3RuQQowNeQCmpwU9Z5Fo/4uIjPX9ZAGKFHterrAcF2c= X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Nov 2016 02:52:22.4737 (UTC) X-MS-Exchange-CrossTenant-Id: f34e5979-57d9-4aaa-ad4d-b122a662184d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=f34e5979-57d9-4aaa-ad4d-b122a662184d;Ip=[217.140.96.140];Helo=[nebula.arm.com] X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB6PR0802MB2566 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 03, 2016 at 06:16:16PM -0600, Catalin Marinas wrote: > On Thu, Nov 03, 2016 at 10:27:38AM +0800, Huang Shijie wrote: > > diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c > > index 2e49bd2..4811ef1 100644 > > --- a/arch/arm64/mm/hugetlbpage.c > > +++ b/arch/arm64/mm/hugetlbpage.c > > @@ -61,10 +61,6 @@ static int find_num_contig(struct mm_struct *mm, unsigned long addr, > > return 1; > > } > > pmd = pmd_offset(pud, addr); > > - if (!pmd_present(*pmd)) { > > - VM_BUG_ON(!pmd_present(*pmd)); > > - return 1; > > - } > > if ((pte_t *)pmd == ptep) { > > *pgsize = PMD_SIZE; > > return CONT_PMDS; > > BTW, for the !pud_present() and !pgd_present() cases, shouldn't The kernel will not call the find_num_contig() if the PGD/PUD are empty. Please see the code in the hugetlb_fault(). ------------------------------------------------------ ptep = huge_pte_offset(mm, address); if (ptep) { ............................... } else { ptep = huge_pte_alloc(mm, address, huge_page_size(h)); if (!ptep) return VM_FAULT_OOM; } ------------------------------------------------------ Thanks Huang Shijie > find_num_contig() actually return 0? These are more likely real bugs, so > no point in setting the huge pte.