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=-0.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 C8E38C3F2D1 for ; Thu, 5 Mar 2020 18:34:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A5FA222522 for ; Thu, 5 Mar 2020 18:34:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chrisdown.name header.i=@chrisdown.name header.b="Az2s3X85" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726162AbgCESe3 (ORCPT ); Thu, 5 Mar 2020 13:34:29 -0500 Received: from mail-wm1-f66.google.com ([209.85.128.66]:40789 "EHLO mail-wm1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725991AbgCESe3 (ORCPT ); Thu, 5 Mar 2020 13:34:29 -0500 Received: by mail-wm1-f66.google.com with SMTP id e26so6820669wme.5 for ; Thu, 05 Mar 2020 10:34:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chrisdown.name; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=wJ+dZCI2bt1Xd92Q8gcINy/Mjz00mboTvZOgg2MiZ/Q=; b=Az2s3X855Yee9bmXQu46ijVabcCPfzqRWC0fXIWABql9qvdRJREScafWu3/RuhgSZu j4zu1EG9DYlfH1ymfLDTZX07SiFFS4XIvrkPVnNZt41vphnMSbVDpEJJ5ssq1hWz3/L/ xc3wSL5sORqcP4T1T/bEHP3MxEhe85fLbf6ZQ= 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; bh=wJ+dZCI2bt1Xd92Q8gcINy/Mjz00mboTvZOgg2MiZ/Q=; b=XPh7cGJklqG2qYDhdyLMt+YaeZZNT1dxniDQH3o0toLB/noN7w3mJgKdn84yBVwekQ icXv+gdCDT9rSexyZLICC5fDz/YtYLiZKEbomvkt8MUyUEHCnu6A7i7GMCRstBTT6klq fPa2pB2dxXzZd9Vcw87yhCN8S9WBXIkmcsCdGp14wcyHzgITA64OPhwVTyQsE0t7hVKi N+/OlbPQ4P/2li72xtz6apjwkyWNevyLYrAq2YzdhlomtWcHiSIGzQWWO6wOroa/k1Ms r7GVbU2PyqbYlBxJwcWEpyXQMFOMMi5ghGOQCZHctyzsC6erFRJIjwdFUFHfiIF+IWcp lYSQ== X-Gm-Message-State: ANhLgQ2pMuJAYCmPtDb5TlfF7k3g4cGLY99QInIDCqduTtuns23uZOSs DdxHqJ0BNYWhJylRPmX8afAmAw== X-Google-Smtp-Source: ADFU+vvQkILMu/20lzgmWDM1ZZQvdG4mimL+9eMS9uDilaKhzhTYYE9iHYxOxeEPWCHv0qyCCN2hFg== X-Received: by 2002:a1c:7c08:: with SMTP id x8mr102447wmc.71.1583433267434; Thu, 05 Mar 2020 10:34:27 -0800 (PST) Received: from localhost ([2620:10d:c092:180::1:6808]) by smtp.gmail.com with ESMTPSA id l4sm47313781wrv.22.2020.03.05.10.34.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Mar 2020 10:34:26 -0800 (PST) Date: Thu, 5 Mar 2020 18:34:26 +0000 From: Chris Down To: Johannes Weiner Cc: Vincenzo Frascino , Michal Hocko , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vladimir Davydov , Andrew Morton Subject: Re: [PATCH] mm: Make mem_cgroup_id_get_many dependent on MMU and MEMCG_SWAP Message-ID: <20200305183426.GA752201@chrisdown.name> References: <20200304142348.48167-1-vincenzo.frascino@arm.com> <20200304165336.GO16139@dhcp22.suse.cz> <8c489836-b824-184e-7cfe-25e55ab73000@arm.com> <20200305160929.GA1166@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20200305160929.GA1166@cmpxchg.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Johannes Weiner writes: >I would ack a patch that adds __maybe_unused. > >This is a tiny function. If we keep it around a few releases after >removing the last user, it costs us absolutely nothing. Eventually >somebody will notice and send a patch to remove it. No big deal. > >There is, however, real cost in keeping bogus warnings around and >telling people to ignore them. It's actively lowering the >signal-to-noise ratio and normalizing warnings to developers. That's >the kind of thing that will actually hide problems in the kernel. > >We know that the function can be unused in certain scenarios. It's >silly to let the compiler continue to warn about it. That's exactly >what __maybe_unused is for, so let's use it here. Yeah, this is exactly what I was trying to express in the first one[0]. The fact that this patch came around a second time, as expected, just solidifies my concern around the waste to human time. I would also ack a patch that adds __maybe_unused. 0: https://lore.kernel.org/linux-mm/20191217143720.GB131030@chrisdown.name/