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 6EA1FC3F2D2 for ; Thu, 5 Mar 2020 18:34:30 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2F9C7208C3 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" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2F9C7208C3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chrisdown.name Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id BA69B6B0005; Thu, 5 Mar 2020 13:34:29 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B7CD26B0006; Thu, 5 Mar 2020 13:34:29 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A92976B0007; Thu, 5 Mar 2020 13:34:29 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0162.hostedemail.com [216.40.44.162]) by kanga.kvack.org (Postfix) with ESMTP id 900F56B0005 for ; Thu, 5 Mar 2020 13:34:29 -0500 (EST) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 63AB3180AD801 for ; Thu, 5 Mar 2020 18:34:29 +0000 (UTC) X-FDA: 76562159058.28.ear40_272525291564c X-HE-Tag: ear40_272525291564c X-Filterd-Recvd-Size: 4088 Received: from mail-wm1-f68.google.com (mail-wm1-f68.google.com [209.85.128.68]) by imf24.hostedemail.com (Postfix) with ESMTP for ; Thu, 5 Mar 2020 18:34:28 +0000 (UTC) Received: by mail-wm1-f68.google.com with SMTP id a132so7506243wme.1 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=AdebRhCrm+v6I9rqexKhu72+BNCUOz4Kk87CD0G9eCD4nZeN6/iayLXAOg3WTz3uyA 97m9OerkkIq9hjPCDE+MHZfscM9Vgiw1Zc6blfJEqn7umuntzRQRJkaL7dnntrOXRhJy 5BWdfwNYO7nP2FovF4bdAq6GDBGhTfpLFwwuRrU5kajSoREnFUGyKDEIX9znfSbfAGN/ nqu+BnqR5mhiaryBEO8549TPz0blGg64Pnvm1lVodVPE31R9gipU9Iu6qqWFzDwAYBej tbVQDK7LjRsoAHvs1J3XWLRLq23RcmKA4lxgA5ZitJP82AYcCUFotI8W0ag6mckB7D9f s+lA== X-Gm-Message-State: ANhLgQ1i6M96Ha0khpEYmePES2sEZwKUsfCgS4PWSxodFTuvqUaG0iyj AcAzQ7+qkzFXjRgWEu+1J1kMOA== 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> 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: 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/