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 01B27C433F5 for ; Thu, 30 Aug 2018 10:44:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9CD832082A for ; Thu, 30 Aug 2018 10:44:10 +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="T7pu6AXt" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9CD832082A 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 S1728462AbeH3Opj (ORCPT ); Thu, 30 Aug 2018 10:45:39 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:42658 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728318AbeH3Opi (ORCPT ); Thu, 30 Aug 2018 10:45:38 -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=HMaV9aV35at75yfGy91egTbg5GqQTmnRPaJBHgDSt2I=; b=T7pu6AXtvQ+edG8jhsQSy0GGE pO/rGkc6k+ncvrUImTTQZ1MCsXXU/jKqSRJ/Q2tnJcv23SmegPRYvFss2Y0v7RNtTdUxmu9SfAK1R gnePjuh0DAAVGlWl5TsogsDJpJZG53b5zDw6Ah/CKcBqQjDwPorse4kbD80h/FJg7d9HfBYyt4jFI Z7ukRABs+s8eGHp/NTrlmkUljZEtHt19SN3L7mayuDvhIaZqPJO679f/SFgXa6ixzOUaOB+7nH8Iw dJiHFJOhXsN+nWvq/P4GUG7RjWedK+pwQ4vSRqdSE8g2qxcZuiAMTp5ZtT9YtBfCW8Q8YBfVn2igd DYxTQte5Q==; 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 1fvKQl-0007MC-G5; Thu, 30 Aug 2018 10:44:03 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 0AE6B2024D444; Thu, 30 Aug 2018 12:44:02 +0200 (CEST) Date: Thu, 30 Aug 2018 12:44:02 +0200 From: Peter Zijlstra To: Feng Tang Cc: 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: <20180830104401.GZ24124@hirez.programming.kicks-ass.net> References: <20180830090319.985-1-feng.tang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180830090319.985-1-feng.tang@intel.com> 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 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.