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[68.232.141.245]) by mx.google.com with ESMTPS id d125si5864037pgc.444.2017.10.19.08.05.53 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 19 Oct 2017 08:05:53 -0700 (PDT) From: Bart Van Assche Subject: Re: [PATCH v2 2/3] lockdep: Remove BROKEN flag of LOCKDEP_CROSSRELEASE Date: Thu, 19 Oct 2017 15:05:28 +0000 Message-ID: <1508425527.2429.11.camel@wdc.com> References: <1508392531-11284-1-git-send-email-byungchul.park@lge.com> <1508392531-11284-3-git-send-email-byungchul.park@lge.com> In-Reply-To: <1508392531-11284-3-git-send-email-byungchul.park@lge.com> Content-Language: en-US Content-Type: text/plain; charset="utf-8" Content-ID: Content-Transfer-Encoding: base64 MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: "mingo@kernel.org" , "peterz@infradead.org" , "byungchul.park@lge.com" Cc: "tglx@linutronix.de" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "kernel-team@lge.com" T24gVGh1LCAyMDE3LTEwLTE5IGF0IDE0OjU1ICswOTAwLCBCeXVuZ2NodWwgUGFyayB3cm90ZToN Cj4gTm93IHRoZSBwZXJmb3JtYW5jZSByZWdyZXNzaW9uIHdhcyBmaXhlZCwgcmUtZW5hYmxlDQo+ IENPTkZJR19MT0NLREVQX0NST1NTUkVMRUFTRSBhbmQgQ09ORklHX0xPQ0tERVBfQ09NUExFVElP TlMuDQo+IA0KPiBTaWduZWQtb2ZmLWJ5OiBCeXVuZ2NodWwgUGFyayA8Ynl1bmdjaHVsLnBhcmtA bGdlLmNvbT4NCj4gLS0tDQo+ICBsaWIvS2NvbmZpZy5kZWJ1ZyB8IDQgKystLQ0KPiAgMSBmaWxl IGNoYW5nZWQsIDIgaW5zZXJ0aW9ucygrKSwgMiBkZWxldGlvbnMoLSkNCj4gDQo+IGRpZmYgLS1n aXQgYS9saWIvS2NvbmZpZy5kZWJ1ZyBiL2xpYi9LY29uZmlnLmRlYnVnDQo+IGluZGV4IDkwZWE3 ODQuLmZlOGZjZWIgMTAwNjQ0DQo+IC0tLSBhL2xpYi9LY29uZmlnLmRlYnVnDQo+ICsrKyBiL2xp Yi9LY29uZmlnLmRlYnVnDQo+IEBAIC0xMTM4LDggKzExMzgsOCBAQCBjb25maWcgUFJPVkVfTE9D S0lORw0KPiAgCXNlbGVjdCBERUJVR19NVVRFWEVTDQo+ICAJc2VsZWN0IERFQlVHX1JUX01VVEVY RVMgaWYgUlRfTVVURVhFUw0KPiAgCXNlbGVjdCBERUJVR19MT0NLX0FMTE9DDQo+IC0Jc2VsZWN0 IExPQ0tERVBfQ1JPU1NSRUxFQVNFIGlmIEJST0tFTg0KPiAtCXNlbGVjdCBMT0NLREVQX0NPTVBM RVRJT05TIGlmIEJST0tFTg0KPiArCXNlbGVjdCBMT0NLREVQX0NST1NTUkVMRUFTRQ0KPiArCXNl bGVjdCBMT0NLREVQX0NPTVBMRVRJT05TDQo+ICAJc2VsZWN0IFRSQUNFX0lSUUZMQUdTDQo+ICAJ ZGVmYXVsdCBuDQo+ICAJaGVscA0KDQpJIGRvIG5vdCBhZ3JlZSB3aXRoIHRoaXMgcGF0Y2guIEFs dGhvdWdoIHRoZSB0cmFkaXRpb25hbCBsb2NrIHZhbGlkYXRpb24NCmNvZGUgY2FuIGJlIHByb3Zl biBub3QgdG8gcHJvZHVjZSBmYWxzZSBwb3NpdGl2ZXMsIHRoYXQgaXMgbm90IHRoZSBjYXNlIGZv cg0KdGhlIGNyb3NzLXJlbGVhc2UgY2hlY2tzLiBUaGVzZSBjaGVja3MgYXJlIHByb25lIHRvIHBy b2R1Y2UgZmFsc2UgcG9zaXRpdmVzLg0KTWFueSBrZXJuZWwgZGV2ZWxvcGVycywgaW5jbHVkaW5n IG15c2VsZiwgYXJlIG5vdCBpbnRlcmVzdGVkIGluIHNwZW5kaW5nDQp0aW1lIG9uIGFuYWx5emlu ZyBmYWxzZSBwb3NpdGl2ZSBkZWFkbG9jayByZXBvcnRzLiBTbyBJIHRoaW5rIHRoYXQgaXQgaXMN Cndyb25nIHRvIGVuYWJsZSBjcm9zcy1yZWxlYXNlIGNoZWNraW5nIHVuY29uZGl0aW9uYWxseSBp ZiBQUk9WRV9MT0NLSU5HIGhhcw0KYmVlbiBlbmFibGVkLiBXaGF0IEkgdGhpbmsgdGhhdCBzaG91 bGQgaGFwcGVuIGlzIHRoYXQgZWl0aGVyIHRoZSBjcm9zcy0NCnJlbGVhc2UgY2hlY2tpbmcgY29k ZSBpcyByZW1vdmVkIGZyb20gdGhlIGtlcm5lbCBvciB0aGF0DQpMT0NLREVQX0NST1NTUkVMRUFT RSBiZWNvbWVzIGEgbmV3IGtlcm5lbCBjb25maWd1cmF0aW9uIG9wdGlvbi4gVGhhdCB3aWxsDQpn aXZlIGtlcm5lbCBkZXZlbG9wZXJzIHdobyBjaG9vc2UgdG8gZW5hYmxlIFBST1ZFX0xPQ0tJTkcg dGhlIGZyZWVkb20gdG8NCmRlY2lkZSB3aGV0aGVyIG9yIG5vdCB0byBlbmFibGUgTE9DS0RFUF9D Uk9TU1JFTEVBU0UuDQoNCkJhcnQu -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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Don't email: email@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754317AbdJSPF5 (ORCPT ); Thu, 19 Oct 2017 11:05:57 -0400 Received: from esa1.hgst.iphmx.com ([68.232.141.245]:41969 "EHLO esa1.hgst.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753803AbdJSPFx (ORCPT ); Thu, 19 Oct 2017 11:05:53 -0400 X-IronPort-AV: E=Sophos;i="5.43,402,1503331200"; d="scan'208";a="161267488" From: Bart Van Assche To: "mingo@kernel.org" , "peterz@infradead.org" , "byungchul.park@lge.com" CC: "tglx@linutronix.de" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "kernel-team@lge.com" Subject: Re: [PATCH v2 2/3] lockdep: Remove BROKEN flag of LOCKDEP_CROSSRELEASE Thread-Topic: [PATCH v2 2/3] lockdep: Remove BROKEN flag of LOCKDEP_CROSSRELEASE Thread-Index: AQHTSJ7m0UDqA3q6tkapniLX+oGlRqLrRiaA Date: Thu, 19 Oct 2017 15:05:28 +0000 Message-ID: <1508425527.2429.11.camel@wdc.com> References: <1508392531-11284-1-git-send-email-byungchul.park@lge.com> <1508392531-11284-3-git-send-email-byungchul.park@lge.com> In-Reply-To: <1508392531-11284-3-git-send-email-byungchul.park@lge.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: spf=none (sender IP is ) smtp.mailfrom=Bart.VanAssche@wdc.com; x-originating-ip: [63.163.107.100] x-ms-publictraffictype: Email x-microsoft-exchange-diagnostics: 1;CY1PR0401MB1533;20:QiQ2bfkho5peneUAw0tIK7C8IHEtuWtlRFVO0BxPBrZVnLohpfHeVTtbWhrA+tUXBYvfzjYNLG+0u5Zt6GyOCtUisjV+Br8aDWi8+2OpQQuNaJjeCpXqUu8tzGdPDB2BTfqplVrgyr277GSE/4LtvYCofDIvuOnpMvjhAbudbCQ= x-ms-exchange-antispam-srfa-diagnostics: SSOS; x-ms-office365-filtering-correlation-id: c601334e-3e24-4996-89a8-08d51702d5e2 x-ms-office365-filtering-ht: Tenant x-microsoft-antispam: UriScan:;BCL:0;PCL:0;RULEID:(22001)(2017030254152)(48565401081)(2017052603199)(201703131423075)(201703031133081)(201702281549075);SRVR:CY1PR0401MB1533; x-ms-traffictypediagnostic: CY1PR0401MB1533: wdcipoutbound: EOP-TRUE x-exchange-antispam-report-test: UriScan:; x-microsoft-antispam-prvs: x-exchange-antispam-report-cfa-test: BCL:0;PCL:0;RULEID:(100000700101)(100105000095)(100000701101)(100105300095)(100000702101)(100105100095)(6040450)(2401047)(5005006)(8121501046)(93006095)(93001095)(10201501046)(3002001)(100000703101)(100105400095)(6055026)(6041248)(20161123564025)(20161123555025)(20161123562025)(20161123560025)(201703131423075)(201702281528075)(201703061421075)(201703061406153)(20161123558100)(6072148)(201708071742011)(100000704101)(100105200095)(100000705101)(100105500095);SRVR:CY1PR0401MB1533;BCL:0;PCL:0;RULEID:(100000800101)(100110000095)(100000801101)(100110300095)(100000802101)(100110100095)(100000803101)(100110400095)(100000804101)(100110200095)(100000805101)(100110500095);SRVR:CY1PR0401MB1533; x-forefront-prvs: 0465429B7F x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(6009001)(346002)(39860400002)(376002)(377424004)(189002)(24454002)(51444003)(199003)(3280700002)(66066001)(103116003)(105586002)(2900100001)(3660700001)(86362001)(189998001)(36756003)(6436002)(2201001)(101416001)(76176999)(50986999)(54356999)(33646002)(6506006)(106356001)(2906002)(68736007)(229853002)(5660300001)(77096006)(6486002)(2950100002)(53936002)(2501003)(305945005)(7736002)(6116002)(14454004)(8936002)(102836003)(54906003)(6246003)(3846002)(72206003)(25786009)(99286003)(97736004)(4001150100001)(6512007)(8676002)(81156014)(478600001)(110136005)(81166006)(4326008)(316002);DIR:OUT;SFP:1102;SCL:1;SRVR:CY1PR0401MB1533;H:CY1PR0401MB1536.namprd04.prod.outlook.com;FPR:;SPF:None;PTR:InfoNoRecords;MX:1;A:1;LANG:en; spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="utf-8" Content-ID: MIME-Version: 1.0 X-OriginatorOrg: wdc.com X-MS-Exchange-CrossTenant-originalarrivaltime: 19 Oct 2017 15:05:28.7153 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: b61c8803-16f3-4c35-9b17-6f65f441df86 X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY1PR0401MB1533 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by nfs id v9JF64wB023192 On Thu, 2017-10-19 at 14:55 +0900, Byungchul Park wrote: > Now the performance regression was fixed, re-enable > CONFIG_LOCKDEP_CROSSRELEASE and CONFIG_LOCKDEP_COMPLETIONS. > > Signed-off-by: Byungchul Park > --- > lib/Kconfig.debug | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 90ea784..fe8fceb 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -1138,8 +1138,8 @@ config PROVE_LOCKING > select DEBUG_MUTEXES > select DEBUG_RT_MUTEXES if RT_MUTEXES > select DEBUG_LOCK_ALLOC > - select LOCKDEP_CROSSRELEASE if BROKEN > - select LOCKDEP_COMPLETIONS if BROKEN > + select LOCKDEP_CROSSRELEASE > + select LOCKDEP_COMPLETIONS > select TRACE_IRQFLAGS > default n > help I do not agree with this patch. Although the traditional lock validation code can be proven not to produce false positives, that is not the case for the cross-release checks. These checks are prone to produce false positives. Many kernel developers, including myself, are not interested in spending time on analyzing false positive deadlock reports. So I think that it is wrong to enable cross-release checking unconditionally if PROVE_LOCKING has been enabled. What I think that should happen is that either the cross- release checking code is removed from the kernel or that LOCKDEP_CROSSRELEASE becomes a new kernel configuration option. That will give kernel developers who choose to enable PROVE_LOCKING the freedom to decide whether or not to enable LOCKDEP_CROSSRELEASE. Bart.