From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932756AbcHJSH3 (ORCPT ); Wed, 10 Aug 2016 14:07:29 -0400 Received: from mail-dm3nam03on0129.outbound.protection.outlook.com ([104.47.41.129]:26934 "EHLO NAM03-DM3-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932410AbcHJSHV (ORCPT ); Wed, 10 Aug 2016 14:07:21 -0400 X-Greylist: delayed 139220 seconds by postgrey-1.27 at vger.kernel.org; Wed, 10 Aug 2016 14:07:21 EDT Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=waiman.long@hpe.com; Message-ID: <57AB6992.6090101@hpe.com> Date: Wed, 10 Aug 2016 13:51:14 -0400 From: Waiman Long User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.12) Gecko/20130109 Thunderbird/10.0.12 MIME-Version: 1.0 To: Peter Zijlstra CC: Ingo Molnar , , Linus Torvalds , Ding Tianhong , Jason Low , Davidlohr Bueso , "Paul E. McKenney" , Thomas Gleixner , Will Deacon , Tim Chen , Imre Deak Subject: Re: [PATCH v4 3/3] locking/mutex: Ensure forward progress of waiter-spinner References: <1468874366-56955-1-git-send-email-Waiman.Long@hpe.com> <1468874366-56955-4-git-send-email-Waiman.Long@hpe.com> <20160808173716.GZ6862@twins.programming.kicks-ass.net> <57AA1A20.4090904@hpe.com> <20160810092905.GN6879@twins.programming.kicks-ass.net> In-Reply-To: <20160810092905.GN6879@twins.programming.kicks-ass.net> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [72.71.243.200] X-ClientProxiedBy: CY1PR08CA0038.namprd08.prod.outlook.com (10.163.94.176) To DF4PR84MB0314.NAMPRD84.PROD.OUTLOOK.COM (10.162.193.28) X-MS-Office365-Filtering-Correlation-Id: ad9613d8-4184-4ba0-e7d3-08d3c146f405 X-Microsoft-Exchange-Diagnostics: 1;DF4PR84MB0314;2:+qVoHl4z1McTB445ZCyRiKs+gAdQ2wlX1SFsOGh1cZmr38GtXzvY5jXYcuUGaLZLXrqlcMf58GocCif8OHrWgVODVyEpCYauMBYVXIPW257+Nms33ihejldhBS8ns+gAewtiFCuxZVkoOtE8YCM/1lYtYRk63PTEqELkXptXngMSVOYD2YBWwwAZ3bBzde8b;3:j8k6RIlcUW6CWglnIo9cRAdPAD6MnxIUXT4TPSA9ISLuIAXzuNdbXxbG/En6OIeoeig4K4zMIfhXYzyoT1fzESeZtjQjsz80jaWvpDnu8rmgBC5LwITD6Oz5jnX8GyRU;25:AM/3kL7D+laxlb6BJOEXY0Hl/qb3eXSohKEvstARbuXQ7wrk9aISr71TFeCcn3FtzDniZ/ZXumRu8Zn+HJZsSFzYZrprsStexIb/Q8YU9MKllf2qMeT3PPwr0b3W26bruFawWLI4bph2wSQs7EMvmeW3KhEXiq/Jif7wpLbeqFZy/EF0qB0kc2FqNjoam0j8zNtpBAtjo1bjEeCXpNDITAkvXLpCYEmA74ozLP4CRVg2BGmF66wP0/vqmThZ6/qaQmm0BuHwgPfio4QHdzcpNX5h5GM75qpmr2FTwvt63ShXoVKJKccV3bmS96qoZ+p13eU8E8dPAZWExwu7a3Zqm3J4ZsZDZ3TCvU4pLlLexdQpT6BGzWmkZMGWKgicf1rutGU9yXR9/CMiUebD9SdGHdPs+GsEO3saKiX9b3Z8hg8= X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:;SRVR:DF4PR84MB0314; X-Microsoft-Exchange-Diagnostics: 1;DF4PR84MB0314;31:VRkrOhtkQWufoBtDZYkfZqs6juFJ9ScgJFgGf8TjXPa3g3nO3sQqbJj3LhJZXTCR+JTdiu1eMs9h9pa7ub1qUiN/praRaVGaVUObWND4OwsG6x+2LiozM8N7DifvAUmSnOSsSqFuUB37u7T6l/jUbTtc+sEajzlNkHfAB7gYOvhAbFcFGVgkve58gzDPA/q3B70ViNcTRQQkclxGxcJ0d3nQbvwtvVEi1cDqPIHB1p8=;20: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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:(601004)(2401047)(8121501046)(5005006)(10201501046)(3002001)(6055026);SRVR:DF4PR84MB0314;BCL:0;PCL:0;RULEID:;SRVR:DF4PR84MB0314; X-Microsoft-Exchange-Diagnostics: 1;DF4PR84MB0314;4:KYYEFZMB4ewjpdEHgnkLznlNHvIs6ZZs3I52Y3G4EiHqmEytzsAY2LKjw90UR1La3u2GJfcwc9JfcDAIDftU68YxaL0NIEBQL3mROL3BYgsbo7AMpT+m4XpO0ggTzRK+/9/2NDjQTtCD3VeomymztwopoWgs4xN8imh9rJF8MP74mXeFa7gmu7wuCQxGww90ZEriUCTeSBYIS9NWWz3Sgs34EUHANb88/jkiw20TWIgmgeNmsS74QLf2vxxod0DqQt3TdlFa1XaHi2dNkGDVObkMD82sku/CYrM+l8ggM7cFP+6tEcRX+1KYqG5EklkKx7JbRY4XnDeDfnxIr92feZrm8dOyG3uaew6yS08jo48eZ7trSzyDbtK8bbk6Adpta/Zl/Hjl8lzzt9iki3qJ9g== X-Forefront-PRVS: 0030839EEE X-Forefront-Antispam-Report: SFV:NSPM;SFS:(10019020)(4630300001)(6049001)(6009001)(7916002)(24454002)(377454003)(189002)(199003)(86362001)(117156001)(97736004)(4001350100001)(76176999)(87266999)(54356999)(36756003)(93886004)(586003)(7416002)(189998001)(50986999)(68736007)(101416001)(59896002)(81166006)(92566002)(81156014)(80316001)(65816999)(8676002)(105586002)(110136002)(83506001)(47776003)(106356001)(305945005)(66066001)(7846002)(7736002)(3846002)(8666005)(50466002)(64126003)(65806001)(6116002)(65956001)(2950100001)(4326007)(2906002)(33656002)(23756003)(230700001)(77096005)(42186005)(7059030);DIR:OUT;SFP:1102;SCL:1;SRVR:DF4PR84MB0314;H:[192.168.142.184];FPR:;SPF:None;PTR:InfoNoRecords;MX:1;A:1;LANG:en; X-Microsoft-Exchange-Diagnostics: =?iso-8859-1?Q?1;DF4PR84MB0314;23:QOEDe17Rc3RZ+JcsX4HKl+Mgvp8KpLtcTcxxUmw?= =?iso-8859-1?Q?OfSnLQx7BKre2mFERileq+WOudd3PE/ocb3gb7nK8e5ajzAFFa3iNCGBhY?= =?iso-8859-1?Q?Moeo0t819LJp+riX7oWBRHONtQ0+9FsIkV46x6esXmr7ucHkGrgfGNzP+Z?= =?iso-8859-1?Q?VRkeDuuvF6lb0LEudZ2faOTAxeU/tyTRuNQIRcgonlJY6NKwSE45/3OBBt?= =?iso-8859-1?Q?2Rr8q9PejONOOJ6SJQnrxj6SOw2sfdSen8lZruN9dMaH/w7760UrlrLOwZ?= =?iso-8859-1?Q?V2Z/1dFo5J4o2oJV6Tv2YQCMpNwPUuXWeEGUG07mIllVyWlTe+h2afDKU3?= =?iso-8859-1?Q?EVfcfD226rfrDp9tAMp89mxsYg6ssBm856qvNamcADbteNzF7Muk/MEtPJ?= =?iso-8859-1?Q?XcLWyN+y8KaK7ok+VMN0HAbF2AKz39nsySYx31UnB4UgyRLvRmSUM0CBTM?= =?iso-8859-1?Q?WGAI9JlYQGf3yLjD2mM8IYlgCi0OaeoEKXhDH6HMdy58XnnkUu67cZz9ba?= =?iso-8859-1?Q?Ys8KFPdLXDcoJDQqAVOTT2lXj8DxdZ9UtDDJMo9Rlzepeg49Y1FeFtEOlJ?= =?iso-8859-1?Q?KCP8RidlfpdtRT4e/FRmjo5sx5sy6MruuJ2vNgpEa8c9KKif/3LUCzt1qJ?= =?iso-8859-1?Q?2x3MJjCwRp6zRUjY1vBM0i+kxQrekVqUpRrTKPDVYpE+NMjwvPc4zfFwj8?= =?iso-8859-1?Q?7ZmJdLngonYvKwfKBqylY5pRsKG8DYyawqQYnlr64p2+pLJ1y4zNxLUh+P?= =?iso-8859-1?Q?YPuzf05rrKVuhFOLg62nEci7oFkSQAzFXutCC37lfpahd3q+sNxHekJ3vW?= =?iso-8859-1?Q?ya81g19XBTNarVsiS/B9mpxtDh4C/PHvDcc1+lezypUPO2/E+M6bhsO3SN?= =?iso-8859-1?Q?IhWUoIn3EGc3K54Gynxcrsz1fNQYV1o82E4X7mmRov8jgw/VcpYuB7X77m?= =?iso-8859-1?Q?YZQjLRRAB8dMo+LqqUFOo5/QFfforszgBxsx55BZaRuGftvd+ohVCksibg?= =?iso-8859-1?Q?eWHp3q5ucmNjYkrZL7PLXeWdyhY+FCwr2ZX+W4ZNmj4IYsjug1CtZQsxhf?= =?iso-8859-1?Q?5e4LFzYY1B5QBUG7FrN1Cf3GHqsy6GKIuFW753whfag0NkfGORZTHT8z8H?= =?iso-8859-1?Q?Vscg80Q3ifnJvZ9zXgBdM++ge8ti9oGsXbdxsqqKZCjI30xGjUv8PngLhP?= =?iso-8859-1?Q?e/0aS8jhWaijyymCL/Xi+MZHfZ+WcgsDdgGRh/ZUs4y0xUXbkGaJIkhtSm?= =?iso-8859-1?Q?tKlgxUpw/93FeT/RrE3Mh/Da2c37GxA5UtZQ336+WHhb6G/aXeeJ07mrBa?= =?iso-8859-1?Q?cYbIAheoj53lapfQrltvhmRrxwECdWaCQTI5kZZ6GJsLV3GyrbAt+uhKGb?= =?iso-8859-1?Q?2iAJIfQOaVp+HK7NimtoHFm1BHVgU?= X-Microsoft-Exchange-Diagnostics: 1;DF4PR84MB0314;6:0mcFUVI1/EqxImHURpjSdTsSupiYSpSBRIN5YmvUVfkS29XGO3xg4RHpl7N83XPdoy2QhKeFoz4rOVBNS2NgwHUOCN6sKdqc1/dd6UVsOZHTEnS7mAX+AKxmLkAhy26mB8bcElYj2pq7b5/KZoC+SZ6UB7L7UJlSFBv2HJh7P/9oymk0MAWnaAZbbuXn3+GGcXhnf4tTzLGitCrAilGIJ5xuVSnMmSna4OZiW/GGtPWJMFiu2NH6r32CPfSFU+9CKu50b/CqdlvzOJeWpNP5z+tJ6F8rbjX5RxocldZLUChzi4b+Il/t1aog1TR8qlJlnSFsL+B0WDHB0vcKY/6nqA==;5:dn6oYP02aaKy3ktaDRWoeczX4Yo/pXIRjQNO7IzbwssKlC62JnDRZFaQ5LmJTCdz8CzIC6JE3GOdvZdfObb1IT1fQRyWzytOZkp/QKXikvn/n537voqW13BoyKvTm+51icUy6350eQYDSAtMjdTnnA==;24:AA95CN6Mb6V4bEDZQDwMbCX+qqnCiMTQebXU0VZFrDfQOcJJ6CuWnIqCWwMG0i/rNa1mGp6iuYjcCJrQh45qb7CH8Qx0skKM5D+ah0n0DLg=;7:kW3+yIIsY51EA9Bbn2mSVsr3ax4bDvIwLn45XGnRKvdFnr2N552DeyX4ej9OGOnSwTPxCPfMRreBuMKUfj/Xf4ArcGLRTZcmNNhHBsZT6mQ/r5SX0iGJMzQ+LLpDEKsZeVNi9XPTzAOF7Q2O0f1C7BxKPH3SaOSIoQFBAta8oUIIOQTsQnYRvUyyhD+mU/OVWsU7qo3BjotZcNRWE1fdhqwqDgH5bhPcQvWnhI7q/AJiRRglTLEn7vevpu4gPVjM SpamDiagnosticOutput: 1:99 SpamDiagnosticMetadata: NSPM X-OriginatorOrg: hpe.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Aug 2016 17:51:26.0717 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-Transport-CrossTenantHeadersStamped: DF4PR84MB0314 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/10/2016 05:29 AM, Peter Zijlstra wrote: > On Tue, Aug 09, 2016 at 02:00:00PM -0400, Waiman Long wrote: >>> Alternative might be to use the LSB of mutex::owner, but that's going to >>> be somewhat icky too. >> I was thinking about doing that. However, the owner field is used in quite a >> number of places. It may be a bit risky to change all of them. > Agreed. > It will be easier to do that for rwsem as the owner field isn't used for the debug code, unlike the mutex. Cheers, Longman