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 9A75AC2D0CD for ; Tue, 17 Dec 2019 15:09:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6FC7E24676 for ; Tue, 17 Dec 2019 15:09:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chrisdown.name header.i=@chrisdown.name header.b="crKI2Mrd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728045AbfLQPJY (ORCPT ); Tue, 17 Dec 2019 10:09:24 -0500 Received: from mail-wr1-f68.google.com ([209.85.221.68]:40956 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727039AbfLQPJY (ORCPT ); Tue, 17 Dec 2019 10:09:24 -0500 Received: by mail-wr1-f68.google.com with SMTP id c14so11688836wrn.7 for ; Tue, 17 Dec 2019 07:09:22 -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=uRifrYHkApcXnKzKR9sZGrhWwRmDmhE0ikbPGadvDHM=; b=crKI2MrdTHir1/QxP/Gc2TF/K5LQOSpYr8URTRvZSMKKZd2IgIojFD0O83S/Bq7wBT yjLxMTafYMdzf3fF/MvlxezrtHOD813wOAA/PfVag2ndv+LWndeMEvvqrBl174t8ahcL v1msU5U/qfNvNJUvqwR/V3PDAfi2JdKH0xG5U= 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=uRifrYHkApcXnKzKR9sZGrhWwRmDmhE0ikbPGadvDHM=; b=iqFLoTB/rJvsWxccRVcW90y2A48hB6pM/WLcLwr8lBSmU/ioBUz9T5eeQIHXHlHjQq GJr4e+4ii73YdAKHmFj/jgBMoKiSq2gUMUlAZnQO01P8DfUZQYWX/FNYyC3hEJx1y+GR 6BbW4tPhdFoYKlUyWLo7lpelcSjB8xv+vuYwB3rkVRWqlRm3hc8Q2uiHboYS4FV7AeJ3 THYkdXp8c7fdunY0a7pV0gXIj9HCjHj8ihD21OrQpPVYRmlvLk5pQxeKg7VRS6X0DdvR GJ+reybFFG9PQyCdusQOPv4lURLYiw/Hn/H+YxVPxeJRFzc27mLi0kMHBZQbSx14/mb9 kGbA== X-Gm-Message-State: APjAAAWj2Q76J+QnRIGAYImHCnAIhGyywjofbM3+Ep0N1DQ+CI5Ne38t KfKmCncUB0YosIfuN7c+8f7AEw== X-Google-Smtp-Source: APXvYqzeUsLeKJ7XhryK7P6j9t84VV3/9Mp+BIfZchRwfo5wRv+dxszHt3anMOTe1fiYJf76De6TAA== X-Received: by 2002:adf:fac1:: with SMTP id a1mr36184936wrs.376.1576595362242; Tue, 17 Dec 2019 07:09:22 -0800 (PST) Received: from localhost ([2620:10d:c092:180::1:f184]) by smtp.gmail.com with ESMTPSA id u18sm25429092wrt.26.2019.12.17.07.09.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Dec 2019 07:09:21 -0800 (PST) Date: Tue, 17 Dec 2019 15:09:21 +0000 From: Chris Down To: Michal Hocko Cc: Qian Cai , 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: <20191217150921.GA136178@chrisdown.name> References: <20191217135440.GB58496@chrisdown.name> <392D7C59-5538-4A9B-8974-DB0B64880C2C@lca.pw> <20191217144652.GA7272@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20191217144652.GA7272@dhcp22.suse.cz> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Michal Hocko writes: >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? There's no way we're the first people to encounter these problems, so what did we do in the past when situations like this (adding a generic API which is not yet used by non-configurable code) came up, and in retrospect did they work well? As far as I know -Wunused-function also guards against other errors, like when a function is prototyped but not actually defined, which might be more useful to know about. (Side note: I'm moderately baffled that a tightly scoped __maybe_unused is considered sinister but somehow disabling -Wunused-function is on the table :-))