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 CD1C1C433F5 for ; Thu, 30 Aug 2018 12:54:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8E99120645 for ; Thu, 30 Aug 2018 12:54:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8E99120645 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 S1728951AbeH3Q4q (ORCPT ); Thu, 30 Aug 2018 12:56:46 -0400 Received: from mga12.intel.com ([192.55.52.136]:15672 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728802AbeH3Q4q (ORCPT ); Thu, 30 Aug 2018 12:56:46 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 30 Aug 2018 05:54:44 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.53,306,1531810800"; d="scan'208";a="69305590" Received: from shbuild888.sh.intel.com (HELO localhost) ([10.239.146.239]) by orsmga008.jf.intel.com with ESMTP; 30 Aug 2018 05:54:43 -0700 Date: Thu, 30 Aug 2018 20:59:09 +0800 From: Feng Tang To: Michal Hocko Cc: Thomas Gleixner , 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: <20180830125909.uq3e76akcmep6j2u@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180830124915.GH2656@dhcp22.suse.cz> 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 02:49:15PM +0200, Michal Hocko wrote: > On Thu 30-08-18 13:54:19, Thomas Gleixner wrote: > > On Thu, 30 Aug 2018, Michal Hocko wrote: > > > On Thu 30-08-18 12:44:02, Peter Zijlstra wrote: > > > > On Thu, Aug 30, 2018 at 05:03:19PM +0800, Feng Tang wrote: > > > > > The root cause is that when CONFIG_NO_BOOTMEM=y, before > > > > > e820__memblock_setup() is called there is no memory for bootmem > > > > > to allocate, > > > > > > > > Which you bloody well asked for by using NO_BOOTMEM=y. > > > > > > > > Going down this route; adding hacks for every little thing that does > > > > want bootmem, completely defeats the purpose. > > > > > > > > If anything, make the earlycon thing depend on NO_BOOTMEM=n. That also > > > > solves your problem. No earlycon, no panic. > > > > > > Well, there is endeavor to remove bootmem allocator altogether. So > > > making earlycon depend on NO_BOOTMEM=n doesn't sound like a good fit to > > > > If we want to remove bootmem, then reintroducing it with a static bootmem > > section doesn't make any sense at all. > > I have actually checked the code now and see what you mean. I thought it > would be a single allocation that is needed but that is not the case so > the static buffer is not going to fly. Exactly! I tried several ways for the static allocation, like in data, in bss section, but they all failed, as in the very start of setup_arch(): memblock_reserve(__pa_symbol(_text), (unsigned long)__bss_stop - (unsigned long)_text); 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. Thanks, Feng