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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 3B8A0C10F03 for ; Thu, 25 Apr 2019 11:42:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 01774208E4 for ; Thu, 25 Apr 2019 11:42:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ZaZUiIhp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730977AbfDYLl5 (ORCPT ); Thu, 25 Apr 2019 07:41:57 -0400 Received: from merlin.infradead.org ([205.233.59.134]:50334 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727500AbfDYLl4 (ORCPT ); Thu, 25 Apr 2019 07:41:56 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=erRFMyCccnjddFJ0MfCAtqH0NA7Ar//n/AsAHoGwyBE=; b=ZaZUiIhpMaVIOvPrOiRNynxVd GkCQP672MFIGqaVKTCMuW8Hzk4/yDSjCKl8ByVA38C7PVMEZQIWXtbsxszXH1OWcaigQIZGUh26lt go9pAx3Y0nWnxPXEWckPy5e2w5IiNeCwKTomCLodq8PtKlkxkUV7QSfirWdCobe1U6rYHMORjm6lU cvuU09xwmWIRlQtubimTJmtDdjsNu9PSMckpjniyQVtvQCMxUpm03KK4Re3iFtIfUcb9pUXGyeymH WsEBh/ZCN1htQYRK1h5rULCpvPeLDPQGnt4gg8TsLhOTk+rYc/qWYUjlnJFv8ZEz4wtJ9N+h9bNgn YzKTHEMgw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hJcl2-0003PT-5l; Thu, 25 Apr 2019 11:41:40 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id ADACA20D0A201; Thu, 25 Apr 2019 13:41:37 +0200 (CEST) Date: Thu, 25 Apr 2019 13:41:37 +0200 From: Peter Zijlstra To: David Laight Cc: 'Thomas Gleixner' , 'Fenghua Yu' , Ingo Molnar , Borislav Petkov , H Peter Anvin , Paolo Bonzini , Dave Hansen , Ashok Raj , Ravi V Shankar , Xiaoyao Li , Christopherson Sean J , Kalle Valo , Michael Chan , linux-kernel , x86 , "kvm@vger.kernel.org" , "netdev@vger.kernel.org" , "linux-wireless@vger.kernel.org" Subject: Re: [PATCH v8 13/15] x86/split_lock: Enable split lock detection by default Message-ID: <20190425114137.GO4038@hirez.programming.kicks-ass.net> References: <1556134382-58814-1-git-send-email-fenghua.yu@intel.com> <1556134382-58814-14-git-send-email-fenghua.yu@intel.com> <762682ba43a0468897ff5ddbf6633d58@AcuMS.aculab.com> <551673e41ac649689243cbe060364b0d@AcuMS.aculab.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <551673e41ac649689243cbe060364b0d@AcuMS.aculab.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Thu, Apr 25, 2019 at 11:13:23AM +0000, David Laight wrote: > I'm not at all sure that 'compare and exchange' operations > are atomic on all cpus if the data is misaligned and crosses > a page boundary and either (or both) pages need faulting in > (or hit a TLB miss). Most sane architectures already trap if you attempt that.