From patchwork Thu Oct 10 20:19:44 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhang Yanfei X-Patchwork-Id: 3018471 Return-Path: X-Original-To: patchwork-linux-acpi@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id A0AA49F245 for ; Thu, 10 Oct 2013 20:20:17 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 5B0982030B for ; Thu, 10 Oct 2013 20:20:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3B980202BE for ; Thu, 10 Oct 2013 20:20:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757031Ab3JJUUM (ORCPT ); Thu, 10 Oct 2013 16:20:12 -0400 Received: from mail-pa0-f47.google.com ([209.85.220.47]:55253 "EHLO mail-pa0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756028Ab3JJUUK (ORCPT ); Thu, 10 Oct 2013 16:20:10 -0400 Received: by mail-pa0-f47.google.com with SMTP id kp14so3241294pab.20 for ; Thu, 10 Oct 2013 13:20:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; bh=Y4FdxRdMwIXrJWtHHCSZUcI0AEzFneQn73eYbHF6UOk=; b=DpMjSXEqHaJEFB1HKQO5cNEgOu6IjiPVdoJInJwyJlVMXu4c0HohA7m5DsNpFmecjl ChMuduDqbFCcDVx+htxAoKRbprdPEDtV1m8P9OlTVb6tEfoZSMC1k58wGkMnOQ3urEM+ YXVV1AXsNbpG8QP/TvCG8eZEuLur8aK5Kshsh6AaQC1VjnIwVhhASY7VgTXnV1UTwor8 3kZft4Q1x4lzDF/1uQeFmV41C4BaxfnoZEME8lCRJiHnpnV3K/B5Lt7Mz54HTBH7pPTn Q1p21CrQ2BEFiJ0/5SwXZKF3r55w6vSUWSU6YMpcUfX8nFKpSvtv1MZiWFoZOjXPAM/s LxUQ== X-Received: by 10.68.245.227 with SMTP id xr3mr10321056pbc.182.1381436410121; Thu, 10 Oct 2013 13:20:10 -0700 (PDT) Received: from localhost.localdomain ([121.225.151.193]) by mx.google.com with ESMTPSA id iu7sm55013379pbc.45.1969.12.31.16.00.00 (version=TLSv1 cipher=RC4-SHA bits=128/128); Thu, 10 Oct 2013 13:20:09 -0700 (PDT) Message-ID: <52570BE0.3040101@gmail.com> Date: Fri, 11 Oct 2013 04:19:44 +0800 From: Zhang Yanfei User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.5) Gecko/20120607 Thunderbird/10.0.5 MIME-Version: 1.0 To: Andrew Morton , "Rafael J . Wysocki" , lenb@kernel.org, Thomas Gleixner , mingo@elte.hu, "H. Peter Anvin" , Tejun Heo , Toshi Kani , Wanpeng Li , Thomas Renninger , Yinghai Lu , Jiang Liu , Wen Congyang , Lai Jiangshan , isimatu.yasuaki@jp.fujitsu.com, izumi.taku@jp.fujitsu.com, Mel Gorman , mina86@mina86.com, Minchan Kim , gong.chen@linux.intel.com, vasilis.liaskovitis@profitbricks.com, lwoodman@redhat.com, Rik van Riel , jweiner@redhat.com, prarit@redhat.com CC: "x86@kernel.org" , linux-doc@vger.kernel.org, "linux-kernel@vger.kernel.org" , Linux MM , linux-acpi@vger.kernel.org, imtangchen@gmail.com, Zhang Yanfei , Tang Chen Subject: [PATCH part1 v7 4/6] x86/mem-hotplug: Support initialize page tables in bottom-up References: <52570A6E.2010806@gmail.com> In-Reply-To: <52570A6E.2010806@gmail.com> Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org X-Spam-Status: No, score=-7.0 required=5.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, T_DKIM_INVALID, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Tang Chen The Linux kernel cannot migrate pages used by the kernel. As a result, kernel pages cannot be hot-removed. So we cannot allocate hotpluggable memory for the kernel. In a memory hotplug system, any numa node the kernel resides in should be unhotpluggable. And for a modern server, each node could have at least 16GB memory. So memory around the kernel image is highly likely unhotpluggable. ACPI SRAT (System Resource Affinity Table) contains the memory hotplug info. But before SRAT is parsed, memblock has already started to allocate memory for the kernel. So we need to prevent memblock from doing this. So direct memory mapping page tables setup is the case. init_mem_mapping() is called before SRAT is parsed. To prevent page tables being allocated within hotpluggable memory, we will use bottom-up direction to allocate page tables from the end of kernel image to the higher memory. Note: As for allocating page tables in lower memory, TJ said: [This is an optional behavior which is triggered by a very specific kernel boot param, which I suspect is gonna need to stick around to support memory hotplug in the current setup unless we add another layer of address translation to support memory hotplug.] As for page tables may occupy too much lower memory if using 4K mapping (CONFIG_DEBUG_PAGEALLOC and CONFIG_KMEMCHECK both disable using >4k pages), TJ said: [But as I said in the same paragraph, parsing SRAT earlier doesn't solve the problem in itself either. Ignoring the option if 4k mapping is required and memory consumption would be prohibitive should work, no? Something like that would be necessary if we're gonna worry about cases like this no matter how we implement it, but, frankly, I'm not sure this is something worth worrying about.] Acked-by: Tejun Heo Acked-by: Toshi Kani Signed-off-by: Tang Chen Signed-off-by: Zhang Yanfei --- arch/x86/mm/init.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++- 1 files changed, 64 insertions(+), 2 deletions(-) diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index ea2be79..b6892a7 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -458,6 +458,51 @@ static void __init memory_map_top_down(unsigned long map_start, init_range_memory_mapping(real_end, map_end); } +/** + * memory_map_bottom_up - Map [map_start, map_end) bottom up + * @map_start: start address of the target memory range + * @map_end: end address of the target memory range + * + * This function will setup direct mapping for memory range + * [map_start, map_end) in bottom-up. Since we have limited the + * bottom-up allocation above the kernel, the page tables will + * be allocated just above the kernel and we map the memory + * in [map_start, map_end) in bottom-up. + */ +static void __init memory_map_bottom_up(unsigned long map_start, + unsigned long map_end) +{ + unsigned long next, new_mapped_ram_size, start; + unsigned long mapped_ram_size = 0; + /* step_size need to be small so pgt_buf from BRK could cover it */ + unsigned long step_size = PMD_SIZE; + + start = map_start; + min_pfn_mapped = start >> PAGE_SHIFT; + + /* + * We start from the bottom (@map_start) and go to the top (@map_end). + * The memblock_find_in_range() gets us a block of RAM from the + * end of RAM in [min_pfn_mapped, max_pfn_mapped) used as new pages + * for page table. + */ + while (start < map_end) { + if (map_end - start > step_size) { + next = round_up(start + 1, step_size); + if (next > map_end) + next = map_end; + } else + next = map_end; + + new_mapped_ram_size = init_range_memory_mapping(start, next); + start = next; + + if (new_mapped_ram_size > mapped_ram_size) + step_size <<= STEP_SIZE_SHIFT; + mapped_ram_size += new_mapped_ram_size; + } +} + void __init init_mem_mapping(void) { unsigned long end; @@ -473,8 +518,25 @@ void __init init_mem_mapping(void) /* the ISA range is always mapped regardless of memory holes */ init_memory_mapping(0, ISA_END_ADDRESS); - /* setup direct mapping for range [ISA_END_ADDRESS, end) in top-down*/ - memory_map_top_down(ISA_END_ADDRESS, end); + /* + * If the allocation is in bottom-up direction, we setup direct mapping + * in bottom-up, otherwise we setup direct mapping in top-down. + */ + if (memblock_bottom_up()) { + unsigned long kernel_end = __pa_symbol(_end); + + /* + * we need two separate calls here. This is because we want to + * allocate page tables above the kernel. So we first map + * [kernel_end, end) to make memory above the kernel be mapped + * as soon as possible. And then use page tables allocated above + * the kernel to map [ISA_END_ADDRESS, kernel_end). + */ + memory_map_bottom_up(kernel_end, end); + memory_map_bottom_up(ISA_END_ADDRESS, kernel_end); + } else { + memory_map_top_down(ISA_END_ADDRESS, end); + } #ifdef CONFIG_X86_64 if (max_pfn > max_low_pfn) {