From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it1-f198.google.com (mail-it1-f198.google.com [209.85.166.198]) by kanga.kvack.org (Postfix) with ESMTP id 2790B8E0001 for ; Mon, 7 Jan 2019 03:38:07 -0500 (EST) Received: by mail-it1-f198.google.com with SMTP id 135so25332itk.5 for ; Mon, 07 Jan 2019 00:38:07 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id l125sor32115426iof.41.2019.01.07.00.38.05 for (Google Transport Security); Mon, 07 Jan 2019 00:38:06 -0800 (PST) MIME-Version: 1.0 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> In-Reply-To: <20190103184706.GU2509588@devbig004.ftw2.facebook.com> From: Pingfan Liu Date: Mon, 7 Jan 2019 16:37:54 +0800 Message-ID: Subject: Re: [PATCHv3 1/2] mm/memblock: extend the limit inferior of bottom-up after parsing hotplug attr Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Tejun Heo Cc: Mike Rapoport , Baoquan He , linux-acpi@vger.kernel.org, linux-mm@kvack.org, kexec@lists.infradead.org, "Rafael J. Wysocki" , Len Brown , Andrew Morton , Mike Rapoport , Michal Hocko , Jonathan Corbet , Yaowei Bai , Nicholas Piggin , Naoya Horiguchi , Daniel Vacek , Mathieu Malaterre , Stefan Agner , Dave Young , yinghai@kernel.org, vgoyal@redhat.com, linux-kernel@vger.kernel.org I send out a series [RFC PATCH 0/4] x86_64/mm: remove bottom-up allocation style by pushing forward the parsing of mem hotplug info ( https://lore.kernel.org/lkml/1546849485-27933-1-git-send-email-kernelfans@gmail.com/T/#t). Please give comment if you are interested. Thanks, Pingfan On Fri, Jan 4, 2019 at 2:47 AM 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. > > Thanks. > > -- > tejun 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,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS 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 8FF8EC43387 for ; Mon, 7 Jan 2019 08:38:08 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 29D71206B7 for ; Mon, 7 Jan 2019 08:38:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="EswmIADM" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 29D71206B7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 701158E000C; Mon, 7 Jan 2019 03:38:07 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 687BF8E0001; Mon, 7 Jan 2019 03:38:07 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 54FE58E000C; Mon, 7 Jan 2019 03:38:07 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from mail-it1-f198.google.com (mail-it1-f198.google.com [209.85.166.198]) by kanga.kvack.org (Postfix) with ESMTP id 2790B8E0001 for ; Mon, 7 Jan 2019 03:38:07 -0500 (EST) Received: by mail-it1-f198.google.com with SMTP id 135so25332itk.5 for ; Mon, 07 Jan 2019 00:38:07 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:mime-version:references :in-reply-to:from:date:message-id:subject:to:cc; bh=CVx1N3/1yZKes91LPFLzCoAaNamYHEmbi9lrJ9mdkOM=; b=SUaEiTmvBZcHOUILEgOkWTOql2h7dPDToPCil7DU3YgcUh/d4XQmUOMtoedLsGZf2x DFevCrOAzWEmDeS5QdoddWhtjdugkxIZx7g49cPcnm34O/mwngtQBCGcGct5M7X9IZRk ZGTXRbadEsEtje1xmtGRFBiWi2iuyFScvaG7jn9SfUztRhPPevtcHBb8x5AgM0m0y15n yBY9o6e6SCnfRgniULad/SSlX/e46oaLUbf9Z6B0soXKePGRKdv7QkdUssZDOiZq8FIi fKxYO6jgWXD/+hH+5Iy8Tp9Bk2bVrEC5UzpeAYsLZIwkRFhcOz+3IcCYjAxu9wJJRmaz AX4Q== X-Gm-Message-State: AJcUukdeeuEWQRU7E8F3P2k4ZHclAdG+43iFiMKtoxVc481RuCiUgWvn dA9v3RJAkkAIKehtw+6HShBHqKJVFGcQ1jyoIp7ldVMSyJwdgmu9aa0yMyf+uyzpdTg+Pdpxf3H wkubWzgxVcULNM7+CNaANPvMZj8ogOGdgADpPCUpBksegnMSvrq/ngxUmon0UqyMXPg+HGJ93Z3 6hoDJc1/uQSMEuvlwWCUDbmg+uOp+ytnLHJszffILRrtqyls2Jfwbdkk6C27VYdl9s5M+U/x67W CODMl4uXFbVNVydZ9n/4knBtFnl7XVnqufRHu5dqro4Dy/niuwOhigwKfloN5wf4ZMF6EHjDfeL 7ychKxqkUk/fE3Op5oy+ABgPGz3fjmuyIJ0GCVRbXc9JRZsedT5e3IF7ztPhixmFAiWLv4fFRyX M X-Received: by 2002:a24:65c8:: with SMTP id u191mr6900633itb.7.1546850286769; Mon, 07 Jan 2019 00:38:06 -0800 (PST) X-Received: by 2002:a24:65c8:: with SMTP id u191mr6900613itb.7.1546850286038; Mon, 07 Jan 2019 00:38:06 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1546850286; cv=none; d=google.com; s=arc-20160816; b=BoE0GM3uJf6ERLFYwDtMUDziDQYO8juTzRQzyWakBPq+cill8+1gHfN+GWEq2dwVGT 6SvwwzRrjURPglI1Lx/993tLn6ubiSI1ZdTp9C0/nnI54avNWSi/V93GkiSu1H4L231d WOrPmxX8y4h/2COUZSGh4m8Ws0zs1QQhr1mQ2VIiywQtlFALidZLovoI0nmdML3tj5aY 1P8WRljgkTrc23fmEJsncSddeJfBJoDS9ZZRJQ06jEoBObKp4kvt5r+dE/RWw5zMM3kH xGMu/5u0nIk4WgVnrMHl7r2bz6k0fmFP+MUBEetf/+3uym0MRPvy9oT8PDXW5Q3qc/uM iTOw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:dkim-signature; bh=CVx1N3/1yZKes91LPFLzCoAaNamYHEmbi9lrJ9mdkOM=; b=bAT+TE2LJyXV/6IKXQFYNzkWbajYC0QL7F2yHLNrlNyxnT344hlegwj8jeMkRzawFR mTxPSbbv4s+80IsVKid0PmkhV2xpkUOZxYaIF0Iezbq7py0VFm7gsFHRa8+zqOGjlxgn Mh0Kh5DtGOIchc5hAJcPjTkpBpxjmt1CcTUxau8Uh+iQ3fEghxyuaqcStugGdH38RCk3 GGnwD+xdfJiWs8F1sjDNnzEvtAlRX4iKLKspjJCeBP6OTJGYoC+QdPEbzhmqrpiLHk1x HZAyi5mU14tZG7pjS0KCSfXdPIRpOtVW84MxAlVxzjjeo7DbRCQfKmc/S2GRPo/1Uh5W 5Kyw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=EswmIADM; spf=pass (google.com: domain of kernelfans@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=kernelfans@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id l125sor32115426iof.41.2019.01.07.00.38.05 for (Google Transport Security); Mon, 07 Jan 2019 00:38:06 -0800 (PST) Received-SPF: pass (google.com: domain of kernelfans@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=EswmIADM; spf=pass (google.com: domain of kernelfans@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=kernelfans@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=CVx1N3/1yZKes91LPFLzCoAaNamYHEmbi9lrJ9mdkOM=; b=EswmIADMoit8HAC/ONWLIUOs82xUyZZ7KMpmO9np6klXABsQU1QTRU18JTuiNxSRAO JqCEQgIK+qEXqqFcT232liEa7b5BoboTP1JaHua26Oxa3PU6ycJYqOje/YOsiHvTN8hu h72X/T2z8V4h4XkHJOprue2txZdkbRWgcW91+MtWEN19h2y984vSFt7LlQpQ8mSXiAZ0 yFG3AunNP1aSP7HEefVBgpijQe27ZzmdODIBmHYBeyWeG5+vk3VBUqgd44hSWiEWf900 HTYM6PegdJmyslG9PeWQE8bjwKTPXGS5giqesuBuGi+5zHfrIQ+1VE8C/UWcQXqXW2Za WaiA== X-Google-Smtp-Source: ALg8bN565vD9gCVSgZ0kouTj2emPGiwItjw1PmyzR2yMpnUaBIORex/wGD7CZ9/km0XWTaveGh3JDkr1kJL25ChZtV0= X-Received: by 2002:a6b:3f06:: with SMTP id m6mr39444084ioa.117.1546850285729; Mon, 07 Jan 2019 00:38:05 -0800 (PST) MIME-Version: 1.0 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> In-Reply-To: <20190103184706.GU2509588@devbig004.ftw2.facebook.com> From: Pingfan Liu Date: Mon, 7 Jan 2019 16:37:54 +0800 Message-ID: Subject: Re: [PATCHv3 1/2] mm/memblock: extend the limit inferior of bottom-up after parsing hotplug attr To: Tejun Heo Cc: Mike Rapoport , Baoquan He , linux-acpi@vger.kernel.org, linux-mm@kvack.org, kexec@lists.infradead.org, "Rafael J. Wysocki" , Len Brown , Andrew Morton , Mike Rapoport , Michal Hocko , Jonathan Corbet , Yaowei Bai , Nicholas Piggin , Naoya Horiguchi , Daniel Vacek , Mathieu Malaterre , Stefan Agner , Dave Young , yinghai@kernel.org, vgoyal@redhat.com, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" 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: Message-ID: <20190107083754.xCTXqk_T4YyKmXaUNGeM1JmfU5J7ptgTswVvgC9Lp50@z> I send out a series [RFC PATCH 0/4] x86_64/mm: remove bottom-up allocation style by pushing forward the parsing of mem hotplug info ( https://lore.kernel.org/lkml/1546849485-27933-1-git-send-email-kernelfans@gmail.com/T/#t). Please give comment if you are interested. Thanks, Pingfan On Fri, Jan 4, 2019 at 2:47 AM 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. > > Thanks. > > -- > tejun