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=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, USER_AGENT_MUTT 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 9B84AC433F4 for ; Thu, 30 Aug 2018 12:09:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4C757205C9 for ; Thu, 30 Aug 2018 12:09:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="nWDTKcRe" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4C757205C9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org 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 S1728800AbeH3QLZ (ORCPT ); Thu, 30 Aug 2018 12:11:25 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:46112 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727876AbeH3QLY (ORCPT ); Thu, 30 Aug 2018 12:11:24 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=oRGaHXS+Aj2z/5xkbJLDj7TIN0E29j8WQ83Y6yUU2z4=; b=nWDTKcRe5z2HrHdD6YkTCCbJ1 dCXg22DCHgRLQFMBfYM6gBp0zDnm/8atXqkeNEvMP355r1H2Jbik1yI444sNCm7icICWwadMjLtEh YoqBuzvJu5P38AwaUvN19g02sCewaaWpak3pLt5CaxPKMAYZZsXI+uZbbuef5Tl/epP1OEsEx5+jg w/DsEzLV6pvPnhF9C1fsXP4nZzrdBd0g+VzU9B8BU93J5ykNk9jHRvqJComqchPJq65KxDZ/lKswp nWiAQvAJzsv+7NL+Rzep/a85apuVq3wrBmY7dB33F1ZJcJFrVAUELE/feOlhNBoRiWO8Tq87hxz9J C0050So8g==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fvLlQ-0004p4-To; Thu, 30 Aug 2018 12:09:29 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id B32D92024D73F; Thu, 30 Aug 2018 14:09:26 +0200 (CEST) Date: Thu, 30 Aug 2018 14:09:26 +0200 From: Peter Zijlstra To: Michal Hocko Cc: Feng Tang , linux-kernel@vger.kernel.org, x86@kernel.org, Thomas Gleixner , 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: <20180830120926.GL24082@hirez.programming.kicks-ass.net> References: <20180830090319.985-1-feng.tang@intel.com> <20180830104401.GZ24124@hirez.programming.kicks-ass.net> <20180830111207.GE2656@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180830111207.GE2656@dhcp22.suse.cz> User-Agent: Mutt/1.10.0 (2018-05-17) 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 01:12:07PM +0200, 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: > > > We hit a kernel panic when enabling earlycon for a platform, the > > > call trace is: > > > > > > 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 > > > > > > 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 wasn't aware of that. why? > making earlycon depend on NO_BOOTMEM=n doesn't sound like a good fit to > me. I am not familiar with this code path but why cannot we postpone the > allocation to later or use a statically allocated storage? because 'early'... I suppose. Youu really want the early con up and running asap.