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=-0.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by aws-us-west-2-korg-lkml-1.web.codeaurora.org (Postfix) with ESMTP id 3E851C5CFC1 for ; Fri, 15 Jun 2018 14:33:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DAB5A208D7 for ; Fri, 15 Jun 2018 14:33:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DAB5A208D7 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=techadventures.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756253AbeFOOdN (ORCPT ); Fri, 15 Jun 2018 10:33:13 -0400 Received: from mail-wm0-f65.google.com ([74.125.82.65]:32888 "EHLO mail-wm0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755816AbeFOOdL (ORCPT ); Fri, 15 Jun 2018 10:33:11 -0400 Received: by mail-wm0-f65.google.com with SMTP id z6-v6so6992047wma.0 for ; Fri, 15 Jun 2018 07:33:11 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=055udI7qFoOJ3wMO5GlogjjaGzc+TKrRAaskuRL9e0I=; b=aioy2l4E94XlHihpS/kxm+52bEqCdHUjIobgqTStF26twkQJTlsYh9y+Gs+35d3pSx FybCnFmIbQB8y9ji7qgxVCGVgN9qdxfwDUnADc72E6xnkJjFdulOdMXlZw2qVtBXjBm9 kONtbEUtk3x8ByvADIXlWD4/0EGofwp9JOOofh+36GyZHWY95MxZSWGgjUSB5O/VhBwo xVAhvOOOUa5T5zQeaRn4jainbeDaiciwzEPiKCjjxW99x1v5g7klmB6JKW19bT0J/mVB DTP8e/ccE+CO780/VMmwwezy5iFqDnooVTlnAC8Rw3Ok4X15B16j0ik0GZgYCdJGganR pfKg== X-Gm-Message-State: APt69E3IZYUAXUzpdUWAuvDLWnHxtIelUUMBCtV0qwr82genTYDZIIlM eg4awzLHqT2xxmboZwf9LdE= X-Google-Smtp-Source: ADUXVKLbraWUhvmxuatIvaz5iyIUDL1RZze56gQbRjCp3Reai6VvmoW8uwIZZCqq/+CBA4OhlQrhfA== X-Received: by 2002:a1c:d388:: with SMTP id k130-v6mr1429911wmg.66.1529073190383; Fri, 15 Jun 2018 07:33:10 -0700 (PDT) Received: from techadventures.net (techadventures.net. [62.201.165.239]) by smtp.gmail.com with ESMTPSA id z83-v6sm1981593wmb.8.2018.06.15.07.33.09 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 15 Jun 2018 07:33:09 -0700 (PDT) Received: by techadventures.net (Postfix, from userid 1000) id AB087123503; Fri, 15 Jun 2018 16:33:08 +0200 (CEST) Date: Fri, 15 Jun 2018 16:33:08 +0200 From: Oscar Salvador To: Pavel Tatashin Cc: Michal Hocko , Naoya Horiguchi , "linux-mm@kvack.org" , Oscar Salvador , Steven Sistare , Daniel Jordan , Matthew Wilcox , "linux-kernel@vger.kernel.org" , Andrew Morton , "mingo@kernel.org" , "dan.j.williams@intel.com" , Huang Ying Subject: Re: [PATCH v3] x86/e820: put !E820_TYPE_RAM regions into memblock.reserved Message-ID: <20180615143308.GA26321@techadventures.net> References: <20180613054107.GA5329@hori1.linux.bs1.fc.nec.co.jp> <20180613090700.GG13364@dhcp22.suse.cz> <20180614051618.GB17860@hori1.linux.bs1.fc.nec.co.jp> <20180614053859.GA9863@techadventures.net> <20180614063454.GA32419@hori1.linux.bs1.fc.nec.co.jp> <20180614213033.GA19374@techadventures.net> <20180615010927.GC1196@hori1.linux.bs1.fc.nec.co.jp> <20180615072947.GB23273@hori1.linux.bs1.fc.nec.co.jp> <20180615084142.GE24039@dhcp22.suse.cz> <20180615140000.44tht4f3ek3lh2u2@xakep.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180615140000.44tht4f3ek3lh2u2@xakep.localdomain> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 15, 2018 at 10:00:00AM -0400, Pavel Tatashin wrote: > On 18-06-15 10:41:42, Michal Hocko wrote: > > On Fri 15-06-18 07:29:48, Naoya Horiguchi wrote: > > [...] > > > From: Naoya Horiguchi > > > Date: Thu, 14 Jun 2018 16:04:36 +0900 > > > Subject: [PATCH] x86/e820: put !E820_TYPE_RAM regions into memblock.reserved > > > > > > There is a kernel panic that is triggered when reading /proc/kpageflags > > > on the kernel booted with kernel parameter 'memmap=nn[KMG]!ss[KMG]': > > > > > > BUG: unable to handle kernel paging request at fffffffffffffffe > > > PGD 9b20e067 P4D 9b20e067 PUD 9b210067 PMD 0 > > > Oops: 0000 [#1] SMP PTI > > > CPU: 2 PID: 1728 Comm: page-types Not tainted 4.17.0-rc6-mm1-v4.17-rc6-180605-0816-00236-g2dfb086ef02c+ #160 > > > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.fc28 04/01/2014 > > > RIP: 0010:stable_page_flags+0x27/0x3c0 > > > Code: 00 00 00 0f 1f 44 00 00 48 85 ff 0f 84 a0 03 00 00 41 54 55 49 89 fc 53 48 8b 57 08 48 8b 2f 48 8d 42 ff 83 e2 01 48 0f 44 c7 <48> 8b 00 f6 c4 01 0f 84 10 03 00 00 31 db 49 8b 54 24 08 4c 89 e7 > > > RSP: 0018:ffffbbd44111fde0 EFLAGS: 00010202 > > > RAX: fffffffffffffffe RBX: 00007fffffffeff9 RCX: 0000000000000000 > > > RDX: 0000000000000001 RSI: 0000000000000202 RDI: ffffed1182fff5c0 > > > RBP: ffffffffffffffff R08: 0000000000000001 R09: 0000000000000001 > > > R10: ffffbbd44111fed8 R11: 0000000000000000 R12: ffffed1182fff5c0 > > > R13: 00000000000bffd7 R14: 0000000002fff5c0 R15: ffffbbd44111ff10 > > > FS: 00007efc4335a500(0000) GS:ffff93a5bfc00000(0000) knlGS:0000000000000000 > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > CR2: fffffffffffffffe CR3: 00000000b2a58000 CR4: 00000000001406e0 > > > Call Trace: > > > kpageflags_read+0xc7/0x120 > > > proc_reg_read+0x3c/0x60 > > > __vfs_read+0x36/0x170 > > > vfs_read+0x89/0x130 > > > ksys_pread64+0x71/0x90 > > > do_syscall_64+0x5b/0x160 > > > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > > RIP: 0033:0x7efc42e75e23 > > > Code: 09 00 ba 9f 01 00 00 e8 ab 81 f4 ff 66 2e 0f 1f 84 00 00 00 00 00 90 83 3d 29 0a 2d 00 00 75 13 49 89 ca b8 11 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 34 c3 48 83 ec 08 e8 db d3 01 00 48 89 04 24 > > > > > > According to kernel bisection, this problem became visible due to commit > > > f7f99100d8d9 which changes how struct pages are initialized. > > > > > > Memblock layout affects the pfn ranges covered by node/zone. Consider > > > that we have a VM with 2 NUMA nodes and each node has 4GB memory, and > > > the default (no memmap= given) memblock layout is like below: > > > > > > MEMBLOCK configuration: > > > memory size = 0x00000001fff75c00 reserved size = 0x000000000300c000 > > > memory.cnt = 0x4 > > > memory[0x0] [0x0000000000001000-0x000000000009efff], 0x000000000009e000 bytes on node 0 flags: 0x0 > > > memory[0x1] [0x0000000000100000-0x00000000bffd6fff], 0x00000000bfed7000 bytes on node 0 flags: 0x0 > > > memory[0x2] [0x0000000100000000-0x000000013fffffff], 0x0000000040000000 bytes on node 0 flags: 0x0 > > > memory[0x3] [0x0000000140000000-0x000000023fffffff], 0x0000000100000000 bytes on node 1 flags: 0x0 > > > ... > > > > > > If you give memmap=1G!4G (so it just covers memory[0x2]), > > > the range [0x100000000-0x13fffffff] is gone: > > > > > > MEMBLOCK configuration: > > > memory size = 0x00000001bff75c00 reserved size = 0x000000000300c000 > > > memory.cnt = 0x3 > > > memory[0x0] [0x0000000000001000-0x000000000009efff], 0x000000000009e000 bytes on node 0 flags: 0x0 > > > memory[0x1] [0x0000000000100000-0x00000000bffd6fff], 0x00000000bfed7000 bytes on node 0 flags: 0x0 > > > memory[0x2] [0x0000000140000000-0x000000023fffffff], 0x0000000100000000 bytes on node 1 flags: 0x0 > > > ... > > > > > > This causes shrinking node 0's pfn range because it is calculated by > > > the address range of memblock.memory. So some of struct pages in the > > > gap range are left uninitialized. > > > > > > We have a function zero_resv_unavail() which does zeroing the struct > > > pages within the reserved unavailable range (i.e. memblock.memory && > > > !memblock.reserved). This patch utilizes it to cover all unavailable > > > ranges by putting them into memblock.reserved. > > > > > > Fixes: f7f99100d8d9 ("mm: stop zeroing memory during allocation in vmemmap") > > > Signed-off-by: Naoya Horiguchi > > > Tested-by: Oscar Salvador > > > > OK, this makes sense to me. It is definitely much better than the > > original attempt. > > > > Unless I am missing something this should be correct > > Acked-by: Michal Hocko > > First of all thank you Naoya for finding and root causing this issue. > > So, with this fix we reserve any hole and !E820_TYPE_RAM or > !E820_TYPE_RESERVED_KERN in e820. I think, this will work because we > do pfn_valid() check in zero_resv_unavail(), so the ranges that do not have > backing struct pages will be skipped. But, I am worried on the performance > implications of when the holes of invalid memory are rather large. We would > have to loop through it in zero_resv_unavail() one pfn at a time. > > Therefore, we might also need to optimize zero_resv_unavail() a little like > this: > > 6407 if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages))) > 6408 continue; > > Add before "continue": > pfn = ALIGN_DOWN(pfn, pageblock_nr_pages) + pageblock_nr_pageas - 1. > At least, this way, we would skip a section of invalid memory at a time. > > For the patch above: > Reviewed-by: Pavel Tatashin > > But, I think the 2nd patch with the optimization above should go along this > this fix. Hi Pavel, I think this makes a lot of sense. Since Naoya is out until Wednesday, maybe I give it a shot next week and see if I can gather some numbers. > > Thank you, > Pasha > > > > > > --- > > > arch/x86/kernel/e820.c | 15 ++++++++++++--- > > > 1 file changed, 12 insertions(+), 3 deletions(-) > > > > > > diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c > > > index d1f25c831447..c88c23c658c1 100644 > > > --- a/arch/x86/kernel/e820.c > > > +++ b/arch/x86/kernel/e820.c > > > @@ -1248,6 +1248,7 @@ void __init e820__memblock_setup(void) > > > { > > > int i; > > > u64 end; > > > + u64 addr = 0; > > > > > > /* > > > * The bootstrap memblock region count maximum is 128 entries > > > @@ -1264,13 +1265,21 @@ void __init e820__memblock_setup(void) > > > struct e820_entry *entry = &e820_table->entries[i]; > > > > > > end = entry->addr + entry->size; > > > + if (addr < entry->addr) > > > + memblock_reserve(addr, entry->addr - addr); > > > + addr = end; > > > if (end != (resource_size_t)end) > > > continue; > > > > > > + /* > > > + * all !E820_TYPE_RAM ranges (including gap ranges) are put > > > + * into memblock.reserved to make sure that struct pages in > > > + * such regions are not left uninitialized after bootup. > > > + */ > > > if (entry->type != E820_TYPE_RAM && entry->type != E820_TYPE_RESERVED_KERN) > > > - continue; > > > - > > > - memblock_add(entry->addr, entry->size); > > > + memblock_reserve(entry->addr, entry->size); > > > + else > > > + memblock_add(entry->addr, entry->size); > > > } > > > > > > /* Throw away partial pages: */ > > > -- > > > 2.7.4 > > > > -- > > Michal Hocko > > SUSE Labs > > > Best Regards Oscar Salvador