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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT 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 61DADC433F4 for ; Thu, 30 Aug 2018 13:51:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 24D70205F4 for ; Thu, 30 Aug 2018 13:51:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 24D70205F4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com 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 S1729040AbeH3Rx3 (ORCPT ); Thu, 30 Aug 2018 13:53:29 -0400 Received: from mga02.intel.com ([134.134.136.20]:11579 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728273AbeH3Rx3 (ORCPT ); Thu, 30 Aug 2018 13:53:29 -0400 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 30 Aug 2018 06:51:12 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.53,307,1531810800"; d="scan'208";a="67167301" Received: from shbuild888.sh.intel.com (HELO localhost) ([10.239.146.239]) by fmsmga008.fm.intel.com with ESMTP; 30 Aug 2018 06:51:10 -0700 Date: Thu, 30 Aug 2018 21:55:36 +0800 From: Feng Tang To: Thomas Gleixner Cc: Michal Hocko , Peter Zijlstra , linux-kernel@vger.kernel.org, x86@kernel.org, Ingo Molnar , "H . Peter Anvin" , Yinghai Lu , Dave Hansen , Andi Kleen Subject: Re: [PATCH] x86, mm: Reserver some memory for bootmem allocator for NO_BOOTMEM Message-ID: <20180830135536.i3fwqaywgtopwxlc@shbuild888> References: <20180830090319.985-1-feng.tang@intel.com> <20180830104401.GZ24124@hirez.programming.kicks-ass.net> <20180830111207.GE2656@dhcp22.suse.cz> <20180830124915.GH2656@dhcp22.suse.cz> <20180830125909.uq3e76akcmep6j2u@shbuild888> <20180830131920.w2jqjvlkpfb4ejb2@shbuild888> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 30, 2018 at 03:25:42PM +0200, Thomas Gleixner wrote: > On Thu, 30 Aug 2018, Feng Tang wrote: > > On Thu, Aug 30, 2018 at 03:05:31PM +0200, Thomas Gleixner wrote: > > > > Those [_text, __bss_stop] is not able to be used by alloc_bootmem(). And I > > > > only got this patch, and really appreciate any good suggestions. > > > > > > And why do you want to use bootmem in the first place? If boot mem is going > > > away, why are you not fixing the early console crap to NOT use bootmem at > > > all? > > > > The earlycon need use fixmap to map the mmio register, while fixmap will > > need a new page for page table if the pmd/pte is not already their, as shown > > in the commit log: > > > > panic+0xd2/0x220 > > __alloc_bootmem+0x31/0x34 > > spp_getpage+0x60/0x8a > > fill_pte+0x71/0x130 > > __set_pte_vaddr+0x1d/0x50 > > set_pte_vaddr+0x3c/0x60 > > __native_set_fixmap+0x23/0x30 > > native_set_fixmap+0x30/0x40 > > setup_earlycon+0x1e0/0x32f > > param_setup_earlycon+0x13/0x22 > > do_early_param+0x5b/0x90 > > parse_args+0x1f7/0x300 > > parse_early_options+0x24/0x28 > > parse_early_param+0x65/0x73 > > setup_arch+0x31e/0x9f1 > > start_kernel+0x58/0x44e > > > > inside the spp_getpage(): > > > > if (after_bootmem) > > ptr = (void *) get_zeroed_page(GFP_ATOMIC); > > else > > ptr = alloc_bootmem_pages(PAGE_SIZE); > > And where is the problem? We know that we need the fixmap during early boot > anyway, so allocating the PTE page statically and setting it up early > enough is not really rocket science. No allocator required. Yes, if the bootmem itslef is going way, setting up the page table for fixmap is a cleaner solution. Thanks, Feng