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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, 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 3D782C43387 for ; Wed, 2 Jan 2019 09:28:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0B25521019 for ; Wed, 2 Jan 2019 09:28:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729189AbfABJ2m (ORCPT ); Wed, 2 Jan 2019 04:28:42 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:37766 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728873AbfABJ2l (ORCPT ); Wed, 2 Jan 2019 04:28:41 -0500 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id x029NU72087467 for ; Wed, 2 Jan 2019 04:28:40 -0500 Received: from e06smtp05.uk.ibm.com (e06smtp05.uk.ibm.com [195.75.94.101]) by mx0a-001b2d01.pphosted.com with ESMTP id 2prt58saxc-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Wed, 02 Jan 2019 04:28:40 -0500 Received: from localhost by e06smtp05.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 2 Jan 2019 09:28:21 -0000 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x029SKc458654784 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 2 Jan 2019 09:28:21 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id DFAAEAE058; Wed, 2 Jan 2019 09:28:20 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4B910AE051; Wed, 2 Jan 2019 09:28:19 +0000 (GMT) Received: from rapoport-lnx (unknown [9.148.8.244]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Wed, 2 Jan 2019 09:28:19 +0000 (GMT) Date: Wed, 2 Jan 2019 11:28:17 +0200 From: Mike Rapoport To: Pingfan Liu Cc: 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 , Baoquan He , yinghai@kernel.org, vgoyal@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCHv3 2/2] x86/kdump: bugfix, make the behavior of crashkernel=X consistent with kaslr References: <1545966002-3075-1-git-send-email-kernelfans@gmail.com> <1545966002-3075-3-git-send-email-kernelfans@gmail.com> <20181231084608.GB28478@rapoport-lnx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-TM-AS-GCONF: 00 x-cbid: 19010209-0020-0000-0000-000002FF732C X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19010209-0021-0000-0000-0000214F7718 Message-Id: <20190102092817.GB22664@rapoport-lnx> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-01-02_03:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1901020086 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 02, 2019 at 02:47:54PM +0800, Pingfan Liu wrote: > On Mon, Dec 31, 2018 at 4:46 PM Mike Rapoport wrote: > > > > On Fri, Dec 28, 2018 at 11:00:02AM +0800, Pingfan Liu wrote: > > > Customer reported a bug on a high end server with many pcie devices, where > > > kernel bootup with crashkernel=384M, and kaslr is enabled. Even > > > though we still see much memory under 896 MB, the finding still failed > > > intermittently. Because currently we can only find region under 896 MB, > > > if w/0 ',high' specified. Then KASLR breaks 896 MB into several parts > > > randomly, and crashkernel reservation need be aligned to 128 MB, that's > > > why failure is found. It raises confusion to the end user that sometimes > > > crashkernel=X works while sometimes fails. > > > If want to make it succeed, customer can change kernel option to > > > "crashkernel=384M, high". Just this give "crashkernel=xx@yy" a very > > > limited space to behave even though its grammer looks more generic. > > > And we can't answer questions raised from customer that confidently: > > > 1) why it doesn't succeed to reserve 896 MB; > > > 2) what's wrong with memory region under 4G; > > > 3) why I have to add ',high', I only require 384 MB, not 3840 MB. > > > > > > This patch simplifies the method suggested in the mail [1]. It just goes > > > bottom-up to find a candidate region for crashkernel. The bottom-up may be > > > better compatible with the old reservation style, i.e. still want to get > > > memory region from 896 MB firstly, then [896 MB, 4G], finally above 4G. > > > > > > There is one trivial thing about the compatibility with old kexec-tools: > > > if the reserved region is above 896M, then old tool will fail to load > > > bzImage. But without this patch, the old tool also fail since there is no > > > memory below 896M can be reserved for crashkernel. > > > > > > [1]: http://lists.infradead.org/pipermail/kexec/2017-October/019571.html > > > Signed-off-by: Pingfan Liu > > > Cc: Tang Chen > > > Cc: "Rafael J. Wysocki" > > > Cc: Len Brown > > > Cc: Andrew Morton > > > Cc: Mike Rapoport > > > Cc: Michal Hocko > > > Cc: Jonathan Corbet > > > Cc: Yaowei Bai > > > Cc: Pavel Tatashin > > > Cc: Nicholas Piggin > > > Cc: Naoya Horiguchi > > > Cc: Daniel Vacek > > > Cc: Mathieu Malaterre > > > Cc: Stefan Agner > > > Cc: Dave Young > > > Cc: Baoquan He > > > Cc: yinghai@kernel.org, > > > Cc: vgoyal@redhat.com > > > Cc: linux-kernel@vger.kernel.org > > > --- > > > arch/x86/kernel/setup.c | 9 ++++++--- > > > 1 file changed, 6 insertions(+), 3 deletions(-) > > > > > > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c > > > index d494b9b..165f9c3 100644 > > > --- a/arch/x86/kernel/setup.c > > > +++ b/arch/x86/kernel/setup.c > > > @@ -541,15 +541,18 @@ static void __init reserve_crashkernel(void) > > > > > > /* 0 means: find the address automatically */ > > > if (crash_base <= 0) { > > > + bool bottom_up = memblock_bottom_up(); > > > + > > > + memblock_set_bottom_up(true); > > > > > > /* > > > * Set CRASH_ADDR_LOW_MAX upper bound for crash memory, > > > * as old kexec-tools loads bzImage below that, unless > > > * "crashkernel=size[KMG],high" is specified. > > > */ > > > crash_base = memblock_find_in_range(CRASH_ALIGN, > > > - high ? CRASH_ADDR_HIGH_MAX > > > - : CRASH_ADDR_LOW_MAX, > > > - crash_size, CRASH_ALIGN); > > > + (max_pfn * PAGE_SIZE), crash_size, CRASH_ALIGN); > > > + memblock_set_bottom_up(bottom_up); > > > > Using bottom-up does not guarantee that the allocation won't fall into a > > removable memory, it only makes it highly probable. > > > > I think that the 'max_pfn * PAGE_SIZE' limit should be replaced with the > > end of the non-removable memory node. > > > Since passing MEMBLOCK_NONE, memblock_find_in_range() ->...-> > __next_mem_range(), there is a logic to guarantee hotmovable memory > will not be stamped over. > if (movable_node_is_enabled() && memblock_is_hotpluggable(m)) > continue; Thanks for the clarification, I've missed that. > Thanks, > Pingfan > > > > + > > > if (!crash_base) { > > > pr_info("crashkernel reservation failed - No suitable area found.\n"); > > > return; > > > -- > > > 2.7.4 > > > > > > > -- > > Sincerely yours, > > Mike. > > > -- Sincerely yours, Mike.