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=-10.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 854FFC56201 for ; Wed, 11 Nov 2020 09:11:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E2495206F1 for ; Wed, 11 Nov 2020 09:11:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="INDM4VtQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726865AbgKKJL0 (ORCPT ); Wed, 11 Nov 2020 04:11:26 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:51618 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726575AbgKKJLP (ORCPT ); Wed, 11 Nov 2020 04:11:15 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1605085874; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=FlZinN9OnNylR1xrMcRKZCPumUU6I2AoyvcUIe4LUBE=; b=INDM4VtQmTfOGmq7ZVNe3uChCPE4tDD1BNuO77rwK0jHf3/AbbftZgL76jXT+tCr06KFGi K0pRIuX3qMa90uVaTCHBYlhFk2G+WkTdr1SLsRe5xmkG4ZDtqG01uXcnnhRjRh0NDfjEzi CXjuLAOQeX83gt2ztzm/0oVrB/UEi7g= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-394-xjpSYL_VPgureiI2gCU0VA-1; Wed, 11 Nov 2020 04:11:09 -0500 X-MC-Unique: xjpSYL_VPgureiI2gCU0VA-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C766D5F9DB; Wed, 11 Nov 2020 09:11:07 +0000 (UTC) Received: from [10.36.114.151] (ovpn-114-151.ams2.redhat.com [10.36.114.151]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2078D1A925; Wed, 11 Nov 2020 09:11:04 +0000 (UTC) Subject: Re: [PATCH] arm64: mm: account for hotplug memory when randomizing the linear region To: Anshuman Khandual , Catalin Marinas , linux-arm-kernel@lists.infradead.org, Ard Biesheuvel Cc: Will Deacon , linux-kernel@vger.kernel.org, Mark Rutland , Steve Capper , Mark Brown , Marc Zyngier , gshan@redhat.com, Robin Murphy , Steven Price References: <20201014081857.3288-1-ardb@kernel.org> <160503561804.1015659.16599672230432576934.b4-ty@arm.com> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <39a6c4a9-bdad-c565-03a0-b60b9811d234@redhat.com> Date: Wed, 11 Nov 2020 10:11:03 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11.11.20 04:48, Anshuman Khandual wrote: > > > On 11/11/20 12:44 AM, Catalin Marinas wrote: >> On Wed, 14 Oct 2020 10:18:57 +0200, Ard Biesheuvel wrote: >>> As a hardening measure, we currently randomize the placement of >>> physical memory inside the linear region when KASLR is in effect. >>> Since the random offset at which to place the available physical >>> memory inside the linear region is chosen early at boot, it is >>> based on the memblock description of memory, which does not cover >>> hotplug memory. The consequence of this is that the randomization >>> offset may be chosen such that any hotplugged memory located above >>> memblock_end_of_DRAM() that appears later is pushed off the end of >>> the linear region, where it cannot be accessed. >>> >>> [...] >> >> Applied to arm64 (for-next/mem-hotplug), thanks! >> >> [1/1] arm64: mm: account for hotplug memory when randomizing the linear region >> https://git.kernel.org/arm64/c/97d6786e0669 >> > > Hello Catalin, > > Got delayed and never made here in time, sorry about that. Nonetheless, > I have got something working with respect to the generic mechanism that > David Hildenbrand had asked for earlier. > > https://patchwork.kernel.org/project/linux-arm-kernel/patch/1600332402-30123-1-git-send-email-anshuman.khandual@arm.com/ > > I am wondering if we could instead consider merging the above patch with > a small change that Ard had pointed out earlier [1], I will send out a > revision if required. > > I am asking this because the patch in question is a memory hotplug fix > and should be back ported to other stable releases. Implementing that > via the new proposed generic framework might make it difficult for a > possible arm64 specific backport. We could then add the new generic > framework and move this fix to an arch callback. Let me know if this > would be an feasible option. Thank you. Sure, if it's a fix that is intended to be backported as well, then let's move forward with the simple fix and do a proper cleanup on top later. Thanks! -- Thanks, David / dhildenb