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=-0.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 EC05EC432C0 for ; Thu, 21 Nov 2019 17:43:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C6A26206CC for ; Thu, 21 Nov 2019 17:43:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726840AbfKURn5 convert rfc822-to-8bit (ORCPT ); Thu, 21 Nov 2019 12:43:57 -0500 Received: from eu-smtp-delivery-151.mimecast.com ([207.82.80.151]:27756 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726279AbfKURn5 (ORCPT ); Thu, 21 Nov 2019 12:43:57 -0500 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mtapsc-6-dpIAySJ5Mz6x9EvXe7vC1g-1; Thu, 21 Nov 2019 17:43:52 +0000 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Thu, 21 Nov 2019 17:43:51 +0000 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Thu, 21 Nov 2019 17:43:51 +0000 From: David Laight To: 'Ingo Molnar' , Peter Zijlstra CC: Fenghua Yu , Thomas Gleixner , Ingo Molnar , Borislav Petkov , H Peter Anvin , Tony Luck , Ashok Raj , Ravi V Shankar , linux-kernel , x86 Subject: RE: [PATCH v10 6/6] x86/split_lock: Enable split lock detection by kernel parameter Thread-Topic: [PATCH v10 6/6] x86/split_lock: Enable split lock detection by kernel parameter Thread-Index: AQHVoI7WvnywFDJ0u0KDgd00OvHm6qeV5GjQ Date: Thu, 21 Nov 2019 17:43:51 +0000 Message-ID: <3481175cbe14457a947f934343946d52@AcuMS.aculab.com> References: <1574297603-198156-1-git-send-email-fenghua.yu@intel.com> <1574297603-198156-7-git-send-email-fenghua.yu@intel.com> <20191121060444.GA55272@gmail.com> <20191121130153.GS4097@hirez.programming.kicks-ass.net> <20191121171214.GD12042@gmail.com> In-Reply-To: <20191121171214.GD12042@gmail.com> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-MC-Unique: dpIAySJ5Mz6x9EvXe7vC1g-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ingo Molnar > Sent: 21 November 2019 17:12 > * Peter Zijlstra wrote: ... > > This feature MUST be default enabled, otherwise everything will > > be/remain broken and we'll end up in the situation where you can't use > > it even if you wanted to. > > Agreed. Before it can be enabled by default someone needs to go through the kernel and fix all the code that abuses the 'bit' functions by using them on int[] instead of long[]. I've only seen one fix go through for one use case of one piece of code that repeatedly uses potentially misaligned int[] arrays for bitmasks. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)