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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 C2E22C33CB7 for ; Mon, 20 Jan 2020 07:48:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9292722522 for ; Mon, 20 Jan 2020 07:48:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579506501; bh=ESoMrB1ai8ZXH9TTW1Cn8bEnDCj+zYfN92K/g1TsCp0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=O22kl+UFLKDEzxEQu6/fNPFkSjk/yzietzjKiU/k87SYHW/a9TiXOyCxIOElA4osy RsbkUD1lydhiF7dSUlY99mk/YAU/HHOtpUJRy1N4/6pMdz1kTeg2b74I+NE0SUnfwX A3rG8IrPt2d16fQ1y5x1Y9fiDtBeRNtXyY9/hvdk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727243AbgATHsU (ORCPT ); Mon, 20 Jan 2020 02:48:20 -0500 Received: from mail-wr1-f65.google.com ([209.85.221.65]:46456 "EHLO mail-wr1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726148AbgATHsU (ORCPT ); Mon, 20 Jan 2020 02:48:20 -0500 Received: by mail-wr1-f65.google.com with SMTP id z7so28328562wrl.13 for ; Sun, 19 Jan 2020 23:48:19 -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=zqYxlN8e9d1Xz81Z1GDVgte6q0CcV1j9cxyhLBRYIzc=; b=p9HJ4veXNlarLtqol+jWVef50Ud8fmZLsaTdr6oy7YjUfCJ4slTr2I95kv42hZ0G2B OLpBphP+Po4QuGnSrO9zHIUJrGrr10wJqjLKK3BEVpndpM34JORhtxvNDNaM6ayslwwW HLZza1W04k7HGK1rPrMvMr9DI0EOSzD399z/XOWxB/I/KTlAkVUv8Jui8ly0JoRfyNII yYi9d7l+C44a1A8/8v0Ibosrb4fAkifY+Xa6FTJntoc31l7YcbI9rsZj46d5cyKj5dKu W+AvtAwVE6BGtw/Atbkfl9x+NtsF12CXazE3KbPc5YQqH6ntItZO2XGoPNm2uD7d3Ogn CWhA== X-Gm-Message-State: APjAAAXEphApqkzNxw2kSVKzsNnOJSrLq4UCZd367Y/Z8WC/LNDtB9rr 1Ry196x2hDzR10Q0gnFINoGNU93M X-Google-Smtp-Source: APXvYqz1nmDNYIQNXhicabxXmw6QCSsn8nPgAPz6zQN+UoT7JCsFPNK6ech+vI4kj8faRntichl/eA== X-Received: by 2002:adf:fe8c:: with SMTP id l12mr16459256wrr.215.1579506498444; Sun, 19 Jan 2020 23:48:18 -0800 (PST) Received: from localhost (ip-37-188-138-155.eurotel.cz. [37.188.138.155]) by smtp.gmail.com with ESMTPSA id u16sm3099104wmj.41.2020.01.19.23.48.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 19 Jan 2020 23:48:17 -0800 (PST) Date: Mon, 20 Jan 2020 08:48:16 +0100 From: Michal Hocko To: Dan Williams Cc: David Hildenbrand , Linux Kernel Mailing List , Linux MM , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Greg Kroah-Hartman , "Rafael J. Wysocki" , Andrew Morton , Leonardo Bras , Nathan Lynch , Allison Randal , Nathan Fontenot , Thomas Gleixner , Stephen Rothwell , Anshuman Khandual , lantianyu1986@gmail.com, linuxppc-dev Subject: Re: [PATCH RFC v1] mm: is_mem_section_removable() overhaul Message-ID: <20200120074816.GG18451@dhcp22.suse.cz> References: <20200117105759.27905-1-david@redhat.com> <20200117113353.GT19428@dhcp22.suse.cz> <20200117145233.GB19428@dhcp22.suse.cz> <65606e2e-1cf7-de3b-10b1-33653cb41a52@redhat.com> <20200117152947.GK19428@dhcp22.suse.cz> <25a94f61-46a1-59a6-6b54-8cc6b35790d2@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 17-01-20 08:57:51, Dan Williams wrote: [...] > Unless the user is willing to hold the device_hotplug_lock over the > evaluation then the result is unreliable. Do we want to hold the device_hotplug_lock from this user readable file in the first place? My book says that this just waits to become a problem. Really, the interface is flawed and should have never been merged in the first place. We cannot simply remove it altogether I am afraid so let's at least remove the bogus code and pretend that the world is a better place where everything is removable except the reality sucks... -- Michal Hocko SUSE Labs