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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 F30E7C04AB4 for ; Tue, 21 May 2019 15:53:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C9A4F2173E for ; Tue, 21 May 2019 15:53:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728742AbfEUPxY (ORCPT ); Tue, 21 May 2019 11:53:24 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:42206 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728114AbfEUPxX (ORCPT ); Tue, 21 May 2019 11:53:23 -0400 Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x4LFqVqB022181 for ; Tue, 21 May 2019 11:53:22 -0400 Received: from e06smtp05.uk.ibm.com (e06smtp05.uk.ibm.com [195.75.94.101]) by mx0a-001b2d01.pphosted.com with ESMTP id 2smjn3d4rm-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 21 May 2019 11:53:22 -0400 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) Tue, 21 May 2019 16:53:14 +0100 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x4LFrDfK42074180 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 21 May 2019 15:53:14 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D560811C058; Tue, 21 May 2019 15:53:13 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3132311C05B; Tue, 21 May 2019 15:53:12 +0000 (GMT) Received: from rapoport-lnx (unknown [9.148.204.239]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Tue, 21 May 2019 15:53:12 +0000 (GMT) Date: Tue, 21 May 2019 18:53:10 +0300 From: Mike Rapoport To: Geert Uytterhoeven Cc: Serge Semin , Ralf Baechle , Paul Burton , James Hogan , Matt Redfearn , Andrew Morton , Michal Hocko , Greg Kroah-Hartman , Thomas Bogendoerfer , Huacai Chen , Stefan Agner , Stephen Rothwell , Alexandre Belloni , Juergen Gross , linux-mips@vger.kernel.org, Linux Kernel Mailing List , Atsushi Nemoto Subject: Re: [PATCH 04/12] mips: Reserve memory for the kernel image resources References: <20190423224748.3765-1-fancer.lancer@gmail.com> <20190423224748.3765-5-fancer.lancer@gmail.com> 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: 19052115-0020-0000-0000-0000033F04C8 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19052115-0021-0000-0000-00002191E561 Message-Id: <20190521155309.GB24470@rapoport-lnx> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-05-21_03:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=2 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-1905210099 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Geert, On Tue, May 21, 2019 at 04:56:39PM +0200, Geert Uytterhoeven wrote: > Hi Serge, > > On Wed, Apr 24, 2019 at 12:50 AM Serge Semin wrote: > > The reserved_end variable had been used by the bootmem_init() code > > to find a lowest limit of memory available for memmap blob. The original > > code just tried to find a free memory space higher than kernel was placed. > > This limitation seems justified for the memmap ragion search process, but > > I can't see any obvious reason to reserve the unused space below kernel > > seeing some platforms place it much higher than standard 1MB. Moreover > > the RELOCATION config enables it to be loaded at any memory address. > > So lets reserve the memory occupied by the kernel only, leaving the region > > below being free for allocations. After doing this we can now discard the > > code freeing a space between kernel _text and VMLINUX_LOAD_ADDRESS symbols > > since it's going to be free anyway (unless marked as reserved by > > platforms). > > > > Signed-off-by: Serge Semin > > This is now commit b93ddc4f9156205e ("mips: Reserve memory for the kernel > image resources") in v5.2-rc1, which causes rbtx4927 to crash during boot: > > VFS: Mounted root (nfs filesystem) on device 0:13. > devtmpfs: mounted > BUG: Bad page state in process swapper pfn:00001 > page:804b7820 refcount:0 mapcount:-128 mapping:00000000 index:0x1 > flags: 0x0() > raw: 00000000 00000100 00000200 00000000 00000001 00000000 ffffff7f 00000000 > page dumped because: nonzero mapcount > Modules linked in: > CPU: 0 PID: 1 Comm: swapper Not tainted > 5.2.0-rc1-rbtx4927-00468-g3c05ea3d4077b756-dirty #137 > Stack : 00000000 10008400 8040dd2c 87c1b974 8044af63 8040dd2c > 00000001 804a3490 > 00000001 81000000 0030f231 80148558 00000003 10008400 > 87c1dd80 7599ee13 > 00000000 00000000 804b0000 00000000 00000007 00000000 > 00000085 00000000 > 62722d31 00000084 804b0000 39347874 00000000 804b7820 > 8040cef8 81000010 > 00000001 00000007 00000001 81000000 00000008 8021de24 > 00000000 804a0000 > ... > Call Trace: > [<8010adec>] show_stack+0x74/0x104 > [<801a5e44>] bad_page+0x130/0x138 > [<801a654c>] free_pcppages_bulk+0x17c/0x3b0 > [<801a789c>] free_unref_page+0x40/0x68 > [<801120f4>] free_init_pages+0xec/0x104 > [<803bdde8>] free_initmem+0x10/0x58 > [<803bdb8c>] kernel_init+0x20/0x100 > [<801057c8>] ret_from_kernel_thread+0x14/0x1c > Disabling lock debugging due to kernel taint > BUG: Bad page state in process swapper pfn:00002 > [...] > > CONFIG_RELOCATABLE is not set, so the only relevant part is the > change quoted below. > > > --- a/arch/mips/kernel/setup.c > > +++ b/arch/mips/kernel/setup.c > > @@ -371,7 +371,6 @@ static void __init bootmem_init(void) > > > > static void __init bootmem_init(void) > > { > > - unsigned long reserved_end; > > phys_addr_t ramstart = PHYS_ADDR_MAX; > > int i; > > > > @@ -382,10 +381,10 @@ static void __init bootmem_init(void) > > * will reserve the area used for the initrd. > > */ > > init_initrd(); > > - reserved_end = (unsigned long) PFN_UP(__pa_symbol(&_end)); > > > > - memblock_reserve(PHYS_OFFSET, > > - (reserved_end << PAGE_SHIFT) - PHYS_OFFSET); > > + /* Reserve memory occupied by kernel. */ > > + memblock_reserve(__pa_symbol(&_text), > > + __pa_symbol(&_end) - __pa_symbol(&_text)); > > > > /* > > * max_low_pfn is not a number of pages. The number of pages > > With some debug code added: > > Determined physical RAM map: > memory: 08000000 @ 00000000 (usable) > bootmem_init:390: PHYS_OFFSET = 0x0 > bootmem_init:391: __pa_symbol(&_text) = 0x100000 > bootmem_init:392: __pa_symbol(&_end) = 0x4b77c8 > bootmem_init:393: PFN_UP(__pa_symbol(&_end)) = 0x4b8 Have you tried adding memblock=debug to the command line? Not sure it'll help, but still :) > Hence the old code reserved 1 MiB extra at the beginning. > > Note that the new code also dropped the rounding up of the memory block > size to a multiple of PAGE_SIZE. I'm not sure the latter actually > matters or not. I'd say that bad page state for pfn 1 is caused by "freeing" the first 1M. > Do you have a clue? Thanks! > > Gr{oetje,eeting}s, > > Geert > > -- > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org > > In personal conversations with technical people, I call myself a hacker. But > when I'm talking to journalists I just say "programmer" or something like that. > -- Linus Torvalds > -- Sincerely yours, Mike.