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=-2.5 required=3.0 tests=MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 655E5C43603 for ; Tue, 17 Dec 2019 14:46:56 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 313CE2072D for ; Tue, 17 Dec 2019 14:46:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 313CE2072D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D44F58E007C; Tue, 17 Dec 2019 09:46:55 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id D1A4F8E0079; Tue, 17 Dec 2019 09:46:55 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C2F8E8E007C; Tue, 17 Dec 2019 09:46:55 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0165.hostedemail.com [216.40.44.165]) by kanga.kvack.org (Postfix) with ESMTP id AEC828E0079 for ; Tue, 17 Dec 2019 09:46:55 -0500 (EST) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 65A1F181AC212 for ; Tue, 17 Dec 2019 14:46:55 +0000 (UTC) X-FDA: 76274910390.20.burn04_22cc90f6493c X-HE-Tag: burn04_22cc90f6493c X-Filterd-Recvd-Size: 3354 Received: from mail-wm1-f66.google.com (mail-wm1-f66.google.com [209.85.128.66]) by imf33.hostedemail.com (Postfix) with ESMTP for ; Tue, 17 Dec 2019 14:46:54 +0000 (UTC) Received: by mail-wm1-f66.google.com with SMTP id u2so3467924wmc.3 for ; Tue, 17 Dec 2019 06:46:54 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=tO9xCSowUipoQ7W1AR4AKa8ZqnZXGPs6Es0GLJPzMG4=; b=E0JT3LFcHFu5OUdPE9LF/0qU0G8qDwhBV+KOvqI2+4pyYESD5bdFYccZqFolLKpd2Q sYUBw/aH9S6fo61koqRusr8Aiue2Z3j4xh9+iYqyvD6X6qTCpiWdflNf2cnJuTJ4PbBm 7Cy5SS6ZLPPWXF0adAi5DbcOzr7tR4++ZzM1Z+C6ksZEt0tDZkp5mmyZESN0dbzQyJuW 6I1hkg0abMSVrwsF2oLCZyRJjxEltQmVfW92taRYWipV6ruXarnS8HYGogqJFyVMuEUq ObIz9plwWX6lHPqHvYu7ytfNVxRMkd87JzSdVXtwBRC/bF9inu5dKHOHhzs5TzCWEa4p LGAw== X-Gm-Message-State: APjAAAUvdmIdpqw95hvKfW97csRWC8j7WoqyHTfBqggDdvAF1agCIxtF VRr4Wi+pWHliA87GJEaw8tc= X-Google-Smtp-Source: APXvYqyQRDROOdlH8DpI5kAyQN88ZStAn4sknFkwi74VDSblzzh4EemeMlpYs4PM61Jl1NA5Lndw7g== X-Received: by 2002:a1c:c919:: with SMTP id f25mr5812629wmb.49.1576594013826; Tue, 17 Dec 2019 06:46:53 -0800 (PST) Received: from localhost (prg-ext-pat.suse.com. [213.151.95.130]) by smtp.gmail.com with ESMTPSA id 5sm26063280wrh.5.2019.12.17.06.46.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Dec 2019 06:46:52 -0800 (PST) Date: Tue, 17 Dec 2019 15:46:52 +0100 From: Michal Hocko To: Qian Cai Cc: Chris Down , Kuninori Morimoto , Johannes Weiner , Vladimir Davydov , Andrew Morton , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: memcontrol.c: move mem_cgroup_id_get_many under CONFIG_MMU Message-ID: <20191217144652.GA7272@dhcp22.suse.cz> References: <20191217135440.GB58496@chrisdown.name> <392D7C59-5538-4A9B-8974-DB0B64880C2C@lca.pw> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <392D7C59-5538-4A9B-8974-DB0B64880C2C@lca.pw> User-Agent: Mutt/1.12.2 (2019-09-21) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue 17-12-19 09:16:36, Qian Cai wrote: > > > > On Dec 17, 2019, at 8:54 AM, Chris Down wrote: > > > > Let's just add __maybe_unused, since it seems like what we want in this scenario -- it avoids new users having to enter preprocessor madness, while also not polluting the build output. > > __maybe_unused should only be used in the last resort as it mark the compiler to catch the real issues in the future. In this case, it might be better just ignore it as only non-realistic compiling test would use !CONFIG_MMU in this case. yes, I would just ignore this warning. Btw. it seems that this is enabled by default for -Wall. Is this useful for kernel builds at all? Does it realistically help discovering real issues? If not then can we simply blacklist it? -- Michal Hocko SUSE Labs