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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 735F3C43331 for ; Fri, 27 Mar 2020 02:11:46 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 32F9920787 for ; Fri, 27 Mar 2020 02:11:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="DLen94jU" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 32F9920787 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D439D6B0075; Thu, 26 Mar 2020 22:11:45 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CF3936B0078; Thu, 26 Mar 2020 22:11:45 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C303F6B007B; Thu, 26 Mar 2020 22:11:45 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id A96CE6B0075 for ; Thu, 26 Mar 2020 22:11:45 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 8803A584D for ; Fri, 27 Mar 2020 02:11:45 +0000 (UTC) X-FDA: 76639516170.02.berry56_f52e32d5511c X-HE-Tag: berry56_f52e32d5511c X-Filterd-Recvd-Size: 5175 Received: from us-smtp-delivery-74.mimecast.com (us-smtp-delivery-74.mimecast.com [63.128.21.74]) by imf10.hostedemail.com (Postfix) with ESMTP for ; Fri, 27 Mar 2020 02:11:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585275104; 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=sbvFtCf85KjSulH0Bc2qbNSx5w8nx9pPYQwDbWgAZV8=; b=DLen94jUFGe/vuCI1+ez9DMw2F3xm8meCxswTrTjhCmmtShpYM+WhFdGaAFfcgnKJ0ljmb soei5Orkd43kfAD8guakJovqSsjvgTa4jWvrLLkFHYX4FZw0okfv+1Vxp/snaPFmnYHMDv poIAAwKju85P8uiRAUdbGAEUTvsJslo= 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-142-NBt8rRX-MWGT0URuP-JueQ-1; Thu, 26 Mar 2020 22:11:40 -0400 X-MC-Unique: NBt8rRX-MWGT0URuP-JueQ-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 36244107ACC7; Fri, 27 Mar 2020 02:11:39 +0000 (UTC) Received: from localhost (ovpn-12-80.pek2.redhat.com [10.72.12.80]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6B1E619C70; Fri, 27 Mar 2020 02:11:38 +0000 (UTC) Date: Fri, 27 Mar 2020 10:11:35 +0800 From: Baoquan He To: James Morse Cc: kexec@lists.infradead.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, Eric Biederman , Andrew Morton , Catalin Marinas , Will Deacon , Anshuman Khandual , Bhupesh Sharma Subject: Re: [PATCH 0/3] kexec/memory_hotplug: Prevent removal and accidental use Message-ID: <20200327021135.GN3039@MiWiFi-R3L-srv> References: <20200326180730.4754-1-james.morse@arm.com> MIME-Version: 1.0 In-Reply-To: <20200326180730.4754-1-james.morse@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline 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: On 03/26/20 at 06:07pm, James Morse wrote: > Hello! >=20 > arm64 recently queued support for memory hotremove, which led to some > new corner cases for kexec. >=20 > If the kexec segments are loaded for a removable region, that region may > be removed before kexec actually occurs. This causes the first kernel to > lockup when applying the relocations. (I've triggered this on x86 too). Do you mean you use 'kexec -l /boot/vmlinuz-xxxx --initrd ...' to load a kernel, next you hot remove some memory regions, then you execute 'kexec -e' to trigger kexec reboot? I may not get the point clearly, but we usually do the loading and triggering of kexec-ed kernel at the same time.=20 >=20 > The first patch adds a memory notifier for kexec so that it can refuse > to allow in-use regions to be taken offline. >=20 >=20 > This doesn't solve the problem for arm64, where the new kernel must > initially rely on the data structures from the first boot to describe > memory. These don't describe hotpluggable memory. > If kexec places the kernel in one of these regions, it must also provide > a DT that describes the region in which the kernel was mapped as memory. > (and somehow ensure its always present in the future...) >=20 > To prevent this from happening accidentally with unaware user-space, > patches two and three allow arm64 to give these regions a different > name. >=20 > This is a change in behaviour for arm64 as memory hotadd and hotremove > were added separately. >=20 >=20 > I haven't tried kdump. > Unaware kdump from user-space probably won't describe the hotplug > regions if the name is different, which saves us from problems if > the memory is no longer present at kdump time, but means the vmcore > is incomplete. Currently, we will monitor udev events of mem hot add/remove, then reload kdump kernel. That reloading is only update the elfcorehdr, because crashkernel has to be reserved during 1st kernel bootup. I don't think this will have problem. >=20 >=20 > These patches are based on arm64's for-next/core branch, but can all > be merged independently. >=20 > Thanks, >=20 > James Morse (3): > kexec: Prevent removal of memory in use by a loaded kexec image > mm/memory_hotplug: Allow arch override of non boot memory resource > names > arm64: memory: Give hotplug memory a different resource name >=20 > arch/arm64/include/asm/memory.h | 11 +++++++ > kernel/kexec_core.c | 56 +++++++++++++++++++++++++++++++++ > mm/memory_hotplug.c | 6 +++- > 3 files changed, 72 insertions(+), 1 deletion(-) >=20 > --=20 > 2.25.1 >=20 >=20