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 7E4FBCDD1D2 for ; Fri, 27 Sep 2024 19:12:39 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CF4C06B0132; Fri, 27 Sep 2024 15:12:38 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C7CAB6B0133; Fri, 27 Sep 2024 15:12:38 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ACF6F6B0134; Fri, 27 Sep 2024 15:12:38 -0400 (EDT) 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 8E3276B0132 for ; Fri, 27 Sep 2024 15:12:38 -0400 (EDT) Received: from smtpin17.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 0BB10ABDC8 for ; Fri, 27 Sep 2024 19:12:38 +0000 (UTC) X-FDA: 82611464796.17.69ACE15 Received: from frasgout12.his.huawei.com (frasgout12.his.huawei.com [14.137.139.154]) by imf09.hostedemail.com (Postfix) with ESMTP id 9F533140010 for ; Fri, 27 Sep 2024 19:12:32 +0000 (UTC) Authentication-Results: imf09.hostedemail.com; dkim=none; spf=pass (imf09.hostedemail.com: domain of jonas.oberhauser@huaweicloud.com designates 14.137.139.154 as permitted sender) smtp.mailfrom=jonas.oberhauser@huaweicloud.com; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1727464293; a=rsa-sha256; cv=none; b=je519dnSIlEM+r/Fh2+apr4iAS8LzXYkcfdytnoyQiBhdYkX/B/ec3JwS3Fy9S4yGoKKkr HOv8jaFDB2eapeBoMIai8iSz659dV3F8smkoWvr16wD5E12orK+O/tHSRUDxLH9Ml3ok6v qahSQFZlfAGL74+iyf2JPFS+2fBOE+0= ARC-Authentication-Results: i=1; imf09.hostedemail.com; dkim=none; spf=pass (imf09.hostedemail.com: domain of jonas.oberhauser@huaweicloud.com designates 14.137.139.154 as permitted sender) smtp.mailfrom=jonas.oberhauser@huaweicloud.com; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1727464293; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=gtBWCSv7+g2WoUaale2tO8KEkydOHEDePE2wOF2fWtA=; b=UjKzBDQ9ZRUnu2aD1tnHz6Cyzd2YeRNpuioLo6f4QhQMU2uhBE2k3lZrRqvf7IQGBgh0Ui z2pKCWYcjnRKGIzrfILiZFzTFEfWj8Y4ZTybOge73GPK9bmqnHpW160yKTV6XgpIzLWteQ j6d/B6hYKRgsn5U+I6GgLOB2qAozkAk= Received: from mail.maildlp.com (unknown [172.18.186.51]) by frasgout12.his.huawei.com (SkyGuard) with ESMTP id 4XFfZc01Nfz9v7Jj for ; Sat, 28 Sep 2024 02:46:48 +0800 (CST) Received: from mail02.huawei.com (unknown [7.182.16.27]) by mail.maildlp.com (Postfix) with ESMTP id B6DFB14010C for ; Sat, 28 Sep 2024 03:12:27 +0800 (CST) Received: from [10.81.203.162] (unknown [10.81.203.162]) by APP2 (Coremail) with SMTP id GxC2BwAniMiMA_dm8ODFAQ--.41972S2; Fri, 27 Sep 2024 20:12:27 +0100 (CET) Message-ID: <1b04e35c-8994-48d9-907a-966bb4dfabaf@huaweicloud.com> Date: Fri, 27 Sep 2024 21:12:09 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 1/4] hazptr: Add initial implementation of hazard pointers To: Linus Torvalds , Mathieu Desnoyers Cc: Boqun Feng , linux-kernel@vger.kernel.org, rcu@vger.kernel.org, linux-mm@kvack.org, lkmm@lists.linux.dev, "Paul E. McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , "Uladzislau Rezki (Sony)" , rostedt , Lai Jiangshan , Zqiang , Peter Zijlstra , Ingo Molnar , Will Deacon , Waiman Long , Mark Rutland , Thomas Gleixner , Kent Overstreet , Vlastimil Babka , maged.michael@gmail.com, Neeraj Upadhyay , Greg Kroah-Hartman References: <4167e6f5-4ff9-4aaa-915e-c1e692ac785a@efficios.com> <48992c9f-6c61-4716-977c-66e946adb399@efficios.com> <2b2aea37-06fe-40cb-8458-9408406ebda6@efficios.com> <55633835-242c-4d7f-875b-24b16f17939c@huaweicloud.com> <54487a36-f74c-46c3-aed7-fc86eaaa9ca2@huaweicloud.com> <0b262fe5-2fc5-478d-bf66-f208723238d5@efficios.com> <7e1c8a5e-c110-414c-8fb2-022eacc2bd4a@efficios.com> <34ec590c-b109-44a0-8bfe-8aafc6e7ad64@efficios.com> From: Jonas Oberhauser In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CM-TRANSID:GxC2BwAniMiMA_dm8ODFAQ--.41972S2 X-Coremail-Antispam: 1UD129KBjDUn29KB7ZKAUJUUUUU529EdanIXcx71UUUUU7v73 VFW2AGmfu7bjvjm3AaLaJ3UjIYCTnIWjp_UUUYs7kC6x804xWl14x267AKxVWrJVCq3wAF c2x0x2IEx4CE42xK8VAvwI8IcIk0rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII 0Yj41l84x0c7CEw4AK67xGY2AK021l84ACjcxK6xIIjxv20xvE14v26r1j6r1xM28EF7xv wVC0I7IYx2IY6xkF7I0E14v26r4j6F4UM28EF7xvwVC2z280aVAFwI0_Gr0_Cr1l84ACjc xK6I8E87Iv6xkF7I0E14v26r4j6r4UJwAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40E FcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr 0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcVAKI48JM4IIrI8v6xkF7I0E8cxan2IY 04v7MxAIw28IcxkI7VAKI48JMxAqzxv26xkF7I0En4kS14v26r4a6rW5MxC20s026xCaFV Cjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWl x4CE17CEb7AF67AKxVW8ZVWrXwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r 1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwCI42IY6xAIw20EY4v20xvaj40_Jr0_ JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcS sGvfC2KfnxnUUI43ZEXa7IU1c4S7UUUUU== X-CM-SenderInfo: 5mrqt2oorev25kdx2v3u6k3tpzhluzxrxghudrp/ X-Stat-Signature: 41j6qtbouiaxpe7a6s1ehu4tb93xxum6 X-Rspamd-Queue-Id: 9F533140010 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1727464352-686902 X-HE-Meta: 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 uOrYxQRq bH/ZvfCS9bmK7ggodFR3QQxfi7euK56zUHQ5i8OY3BdndeAO+N8cS7XC4zRji5RdwUR/TIDs7nzztew1w2w4y+ya5gHugLQwHN+QNkhUSpiLEHewfsFY2w6YRrKKWFCE5y0qXKcYYulTiA/RGFm4egGZmjiSTAhXDh69dIE5CUv2vcIGmzBXV4NCl6VZdeh07TlUJm7z8gzmHzlncj58s/IMq22fKF4etNesL8lpo9KMIJQG6FRN9EUAXXqZNALNQTQnXIhs6osWGaFTtgEaUl2bdzw== 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: List-Subscribe: List-Unsubscribe: Am 9/27/2024 um 8:13 PM schrieb Linus Torvalds: > Because even hiding the value one from the compiler will mean that it > can't use the comparison to decide that the originals are equal, even > if one of them is unhidden. > > No? > > Linus I think it depends on which one you hide. If you do z = b; hide(z); if (a==z) { *b; } then it will be fine, because it knows a==z but nothing about the relation of b with a or z. But for z = a; hide(z); if (z==b) { *b; } then it would still know that b == z, and could replace *b with *z (which really is *a). Best wishes, jonas