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=-5.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 DEFD8C43387 for ; Thu, 3 Jan 2019 18:47:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B10A92184B for ; Thu, 3 Jan 2019 18:47:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546541233; bh=g2HH9JarLGmtyTiZKCPjZu7qVyP+a9isFYubhO4rW0I=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=0uZOlCFzfjK0O4ROVUw9zXQIL0xq3GUJ4Eaf/HRhxAVvx9vRQGUq0o+/wiE6HoQvY ULBGwjdcW9dukQhtCNwUeTf2tWf1i2gqSnXLE0L9AGGc7ecAE+mzb5QNsFaH6RBfIx /rEwPMKBEPjzuNh171dQuOmF//jzc2ep0NYP0eRM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726494AbfACSrM (ORCPT ); Thu, 3 Jan 2019 13:47:12 -0500 Received: from mail-yw1-f68.google.com ([209.85.161.68]:38462 "EHLO mail-yw1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726163AbfACSrM (ORCPT ); Thu, 3 Jan 2019 13:47:12 -0500 Received: by mail-yw1-f68.google.com with SMTP id d190so12467258ywb.5; Thu, 03 Jan 2019 10:47:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=c4bOgmdZh/nJPyrF+8x/aLXpuypken7zoGySe9tnJ9I=; b=BbF+StVcAsbKYa+YESUcgLIXbzs+ceCqm+J3Pyi9Rw9nhq40x+scqvRmm5u4ZFP1A2 iCXCQZ2qkpz9BVM/5DXLS08lhGlVMnOpJHl/YxDE8aR9IAh4qxsoaGVeWbS3SDI0Yygg GQtrMYby6BZlCM0Ql7Lf/uwr2vaIDXerVzTjJsOagXsqCMnqGqL1pE6z6WHMAq+69Ueh GONVQ5bPh3+F5eWCyaX/P+sEA2wb29Abvid0MvhmWMKzjFs1I4ySQVSbheZ0KpJ31qVU tPEWIWypQ+ZjGi62cFprpsww5zBVZGCwsBENlgMubuNWYph/x1DDwaGq0P13ZCd6fGib dzOA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=c4bOgmdZh/nJPyrF+8x/aLXpuypken7zoGySe9tnJ9I=; b=hSUuTM7GvCJWAihPuZpRO79Z3oITKEDMg8Sn1aclvg9ReYre46K8K1IJ+fHz6UpSvf 2WY0IEyRv/eRNMZSKNny08AR2XR2p5FhyT/ViDrQo5t3d9bew+Va/zGsKiOSC7my9XXc /Mm/xMBkdWElNTfMfHsoZBUqU9PjeQAJDaPACRW1ySg/u3r06jCCOtTwsVp0vBINMRrf kVM8BNw2IW1RXnr1BN2HmNNClrfEycqTQczgAnnP+3NoesKORYkcJTsFKJ2qG0scKCGf NHo2cD+3P/d8HIh7xNtRBABNY/e4NHjwzmZi0KFronB+x1YpVYktLDx6+TETHM3u/yVG 8Wyw== X-Gm-Message-State: AA+aEWZe1Cw41JI6hA/VnQMTENmNuWXJsTxIm/I9nH7juTrDFQvQNerS j/U7p9rx01lLk6Lo9DzCjtw= X-Google-Smtp-Source: AFSGD/XhmAMrMT2qThEcz39tCOTv4k+G229egTs4UbvqWK5EfmjvUHIfyley5dtHnW7qT3bNMGE8Xg== X-Received: by 2002:a81:ad49:: with SMTP id l9mr48990106ywk.260.1546541229988; Thu, 03 Jan 2019 10:47:09 -0800 (PST) Received: from localhost ([2620:10d:c091:200::7:f935]) by smtp.gmail.com with ESMTPSA id o124sm15374839ywe.75.2019.01.03.10.47.08 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 03 Jan 2019 10:47:08 -0800 (PST) Date: Thu, 3 Jan 2019 10:47:06 -0800 From: Tejun Heo To: Mike Rapoport Cc: Baoquan He , Pingfan Liu , linux-acpi@vger.kernel.org, linux-mm@kvack.org, kexec@lists.infradead.org, Tang Chen , "Rafael J. Wysocki" , Len Brown , Andrew Morton , Mike Rapoport , Michal Hocko , Jonathan Corbet , Yaowei Bai , Pavel Tatashin , Nicholas Piggin , Naoya Horiguchi , Daniel Vacek , Mathieu Malaterre , Stefan Agner , Dave Young , yinghai@kernel.org, vgoyal@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCHv3 1/2] mm/memblock: extend the limit inferior of bottom-up after parsing hotplug attr Message-ID: <20190103184706.GU2509588@devbig004.ftw2.facebook.com> References: <1545966002-3075-1-git-send-email-kernelfans@gmail.com> <1545966002-3075-2-git-send-email-kernelfans@gmail.com> <20181231084018.GA28478@rapoport-lnx> <20190102092749.GA22664@rapoport-lnx> <20190102101804.GD1990@MiWiFi-R3L-srv> <20190102170537.GA3591@rapoport-lnx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190102170537.GA3591@rapoport-lnx> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Wed, Jan 02, 2019 at 07:05:38PM +0200, Mike Rapoport wrote: > I agree that currently the bottom-up allocation after the kernel text has > issues with KASLR. But this issues are not necessarily related to the > memory hotplug. Even with a single memory node, a bottom-up allocation will > fail if KASLR would put the kernel near the end of node0. > > What I am trying to understand is whether there is a fundamental reason to > prevent allocations from [0, kernel_start)? > > Maybe Tejun can recall why he suggested to start bottom-up allocations from > kernel_end. That's from 79442ed189ac ("mm/memblock.c: introduce bottom-up allocation mode"). I wasn't involved in that patch, so no idea why the restrictions were added, but FWIW it doesn't seem necessary to me. Thanks. -- tejun