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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12570C4332F for ; Tue, 20 Dec 2022 14:32:02 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9F3238E0005; Tue, 20 Dec 2022 09:32:01 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 97C328E0001; Tue, 20 Dec 2022 09:32:01 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7CEFA8E0005; Tue, 20 Dec 2022 09:32:01 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 691C88E0001 for ; Tue, 20 Dec 2022 09:32:01 -0500 (EST) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id CD5A880C50 for ; Tue, 20 Dec 2022 14:31:52 +0000 (UTC) X-FDA: 80262923664.19.D0ABE55 Received: from mail-qt1-f174.google.com (mail-qt1-f174.google.com [209.85.160.174]) by imf11.hostedemail.com (Postfix) with ESMTP id 09CC34000A for ; Tue, 20 Dec 2022 14:31:49 +0000 (UTC) Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b=aW5RhtAs; dmarc=none; spf=pass (imf11.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.160.174 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1671546710; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=T/NCsYKC04yFcK1fgm0juUVbSixz96HJYgI6+8cFKck=; b=CNZvlGYh1ij+7qJRBeR5PJd0dbzb5Tkj7QiPSws6ysUi8TC5M7oGPmlReQHs36ybjLka+T VsJ3ebtvWQ5rkmfvI82U6/dasojK8HCCzUFs+KA8nPMhLc+t+uXLdYJle3Cu7Xd5JZWPjJ 4WPnlDeadw/P+Ad3rIWCeV9x/DAgvwI= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b=aW5RhtAs; dmarc=none; spf=pass (imf11.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.160.174 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1671546710; a=rsa-sha256; cv=none; b=5rYN+1j/DEyFXvIpt2G4ROKVD88quxiJpDkGgjckt068AdgyTu8an3suELI3+8hzBEx+vE FJpDzCCK/pWZ11iPSepOCHEMLlh+/KwMtmWyJH5RhjrsZiQ6OzVBVmhU6XV0dxrIl8UPx0 o0HqLJrqqvnQLed+MROAwheUkfCmEk0= Received: by mail-qt1-f174.google.com with SMTP id c7so11011102qtw.8 for ; Tue, 20 Dec 2022 06:31:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=T/NCsYKC04yFcK1fgm0juUVbSixz96HJYgI6+8cFKck=; b=aW5RhtAsBkNvIR682pacJYjMBchjsl6CBpgm1GNt+MoU0xR7oZIbXklJVEhSA5imlQ 5u50ol+9QlNXecXRFfrW9BlWpiEgwr54V46RQJ7vPMFVZN8nUM7UL5cjfEyDNsEd6TlT I+s90R9sBzg5F4fXqzDg5UVxzzA1ZnYyjdfck= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=T/NCsYKC04yFcK1fgm0juUVbSixz96HJYgI6+8cFKck=; b=gznjMzRiQ2QkUG6JHQOEMq1QfP9nx4RqKvyMh9sI0wS8VSq9vESWgRi9z0DjRNCI2I JNRVxv9/ebCvaOPVy0WxjUAm/8XApi0VblvfQ9iyen8tfenlmiHpll+6jkbEGoWb4Gvp MgInGHuIKYDdu7J1JY873cAtlJdZ/H+6T7zFdn5E9dLaqNmrQoSh0YuRX7uhtaMYES+q dm9brP+TstXdpQZe1Ib4VW663ksgnKMW+6ktZjc1vtY7YvapFXYUdncUSCLHruCMfpn8 Co/F1Bcr7+qaYqT9hisd5U8kcXEVfXZMzoP72jWfA+0gXwTWKr8/Pw17+UYDS0CdrCqs kD/A== X-Gm-Message-State: ANoB5pnuSODUCO9RSIKSKb093F3qrl/exPz9gJ4wgAkmxdD8bEJSjJe5 lwHdOLM5Pj07T9d8M/0BZ66JR+vEeph99dxl X-Google-Smtp-Source: AA0mqf72rvYwB5siPKBKUZmfv+kcOXjXRCLpdygi8D4ZXPEKtdqITU/Ts/y6v3kkmrGHYuM851Z3Rg== X-Received: by 2002:a05:622a:148:b0:3a8:1ac5:47bd with SMTP id v8-20020a05622a014800b003a81ac547bdmr58192314qtw.32.1671546708850; Tue, 20 Dec 2022 06:31:48 -0800 (PST) Received: from mail-qk1-f171.google.com (mail-qk1-f171.google.com. [209.85.222.171]) by smtp.gmail.com with ESMTPSA id t18-20020a05620a451200b006b5cc25535fsm5148392qkp.99.2022.12.20.06.31.46 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 20 Dec 2022 06:31:47 -0800 (PST) Received: by mail-qk1-f171.google.com with SMTP id o14so2712754qkk.5 for ; Tue, 20 Dec 2022 06:31:46 -0800 (PST) X-Received: by 2002:ac8:4988:0:b0:3a7:ef7b:6aa5 with SMTP id f8-20020ac84988000000b003a7ef7b6aa5mr8424356qtq.436.1671546695878; Tue, 20 Dec 2022 06:31:35 -0800 (PST) MIME-Version: 1.0 References: <20221219153525.632521981@infradead.org> <20221219154119.154045458@infradead.org> In-Reply-To: From: Linus Torvalds Date: Tue, 20 Dec 2022 08:31:19 -0600 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [RFC][PATCH 05/12] arch: Introduce arch_{,try_}_cmpxchg128{,_local}() To: Peter Zijlstra Cc: Boqun Feng , corbet@lwn.net, will@kernel.org, mark.rutland@arm.com, catalin.marinas@arm.com, dennis@kernel.org, tj@kernel.org, cl@linux.com, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, Herbert Xu , davem@davemloft.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, joro@8bytes.org, suravee.suthikulpanit@amd.com, robin.murphy@arm.com, dwmw2@infradead.org, baolu.lu@linux.intel.com, Arnd Bergmann , penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, Andrew Morton , vbabka@suse.cz, roman.gushchin@linux.dev, 42.hyeyoo@gmail.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org, linux-crypto@vger.kernel.org, iommu@lists.linux.dev, linux-arch@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 09CC34000A X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: ke8dui8pxg5tqujbu3s8froshdx5cx63 X-HE-Tag: 1671546709-571000 X-HE-Meta: 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 ryDkLLaT Edy+MgYFZketkSHPOwsNQAWmccGMPIBVzsxHR3vVQOnCPrO0EIw7nYPYyxj5Mf3oGDBio8m4Oio48+FtxW4ZmYw/zxMl7XbAjMyfNvenYvT0kmLuKu/eE1LaEG2JkOtOmLa/LUQ8tYLTxDmdug7BietCmqVm00cnE7KA2b4+P/DlzJKHVqptBc+eRqhbSe30NHdtH52xliymQLMW8bruGgFJ6gsRSJenXGEInC+sbyFDFdqQTBbek+Bf4PJ7lskCa9ANl/jhI+L5Q7t8+VzD5jaRClGL08kvonh1scDkpN1os5Q38CXycj7PrTqKi4577RiMJPlwL6BQT40EfuBGCH5sm/shHltriFXanF8XI8RH4XqPtqmVOU15HbCsukg2f2gLIh2WfawocdBTB3tTyLU1aPgq81j0ETm9c X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Dec 20, 2022 at 5:09 AM Peter Zijlstra wrote: > > On Mon, Dec 19, 2022 at 12:07:25PM -0800, Boqun Feng wrote: > > > > I wonder whether we should use "(*(u128 *)ptr)" instead of "(*(unsigned > > long *) ptr)"? Because compilers may think only 64bit value pointed by > > "ptr" gets modified, and they are allowed to do "useful" optimization. > > In this I've copied the existing cmpxchg_double() code; I'll have to let > the arch folks speak here, I've no clue. It does sound like the right thing to do. I doubt it ends up making a difference in practice, but yes, the asm doesn't have a memory clobber, so the input/output types should be the right ones for the compiler to not possibly do something odd and cache the part that it doesn't see as being accessed. Linus