From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt1-f200.google.com (mail-qt1-f200.google.com [209.85.160.200]) by kanga.kvack.org (Postfix) with ESMTP id 657878E00AE for ; Fri, 4 Jan 2019 10:09:45 -0500 (EST) Received: by mail-qt1-f200.google.com with SMTP id w15so45164710qtk.19 for ; Fri, 04 Jan 2019 07:09:45 -0800 (PST) Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com. [148.163.158.5]) by mx.google.com with ESMTPS id k6si695833qvi.152.2019.01.04.07.09.44 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 04 Jan 2019 07:09:44 -0800 (PST) Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id x04F9CvO110362 for ; Fri, 4 Jan 2019 10:09:44 -0500 Received: from e06smtp05.uk.ibm.com (e06smtp05.uk.ibm.com [195.75.94.101]) by mx0b-001b2d01.pphosted.com with ESMTP id 2pt7x6dqgn-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 04 Jan 2019 10:09:43 -0500 Received: from localhost by e06smtp05.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 4 Jan 2019 15:09:41 -0000 Date: Fri, 4 Jan 2019 17:09:29 +0200 From: Mike Rapoport Subject: Re: [PATCHv3 1/2] mm/memblock: extend the limit inferior of bottom-up after parsing hotplug attr 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> <20190103184706.GU2509588@devbig004.ftw2.facebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190103184706.GU2509588@devbig004.ftw2.facebook.com> Message-Id: <20190104150929.GA32252@rapoport-lnx> Sender: owner-linux-mm@kvack.org List-ID: To: Tejun Heo 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 On Thu, Jan 03, 2019 at 10:47:06AM -0800, Tejun Heo wrote: > 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. I should have added the reference [1] at the first place :) Thanks! [1] https://lore.kernel.org/lkml/20130904192215.GG26609@mtj.dyndns.org/ > Thanks. > > -- > tejun > -- Sincerely yours, Mike.