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,URIBL_BLOCKED,USER_AGENT_GIT 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 0D40FC433F5 for ; Thu, 30 Aug 2018 08:58:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B400C2054F for ; Thu, 30 Aug 2018 08:58:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B400C2054F 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 S1727981AbeH3NAC (ORCPT ); Thu, 30 Aug 2018 09:00:02 -0400 Received: from mga12.intel.com ([192.55.52.136]:52785 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727170AbeH3NAC (ORCPT ); Thu, 30 Aug 2018 09:00:02 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 30 Aug 2018 01:58:56 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.53,306,1531810800"; d="scan'208";a="228840483" Received: from shbuild888.sh.intel.com ([10.239.146.239]) by orsmga004.jf.intel.com with ESMTP; 30 Aug 2018 01:58:54 -0700 From: Feng Tang To: linux-kernel@vger.kernel.org, x86@kernel.org, Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , Yinghai Lu , Peter Zijlstra , Dave Hansen , Andi Kleen Cc: Feng Tang Subject: [PATCH] x86, mm: Reserver some memory for bootmem allocator for NO_BOOTMEM Date: Thu, 30 Aug 2018 17:03:19 +0800 Message-Id: <20180830090319.985-1-feng.tang@intel.com> X-Mailer: git-send-email 2.14.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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, and any alloc_bootmem() in this time window will trigger a panic. Seems this is a known issue as already mentioned in arch/x86/kernel/setup.c: " /* after early param, so could get panic from serial */ memblock_x86_reserve_range_setup_data(); " By reserving some memory in the linker script, small memory request could be fulfilled by bootmem allocator. And this memory region is not wasted, but usable after kernel boot. Signed-off-by: Feng Tang --- arch/x86/include/asm/sections.h | 5 +++++ arch/x86/kernel/setup.c | 12 +++++++++++- arch/x86/kernel/vmlinux.lds.S | 9 +++++++++ 3 files changed, 25 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/sections.h b/arch/x86/include/asm/sections.h index 4a911a382ade..d568829510e4 100644 --- a/arch/x86/include/asm/sections.h +++ b/arch/x86/include/asm/sections.h @@ -9,6 +9,11 @@ extern char __brk_base[], __brk_limit[]; extern struct exception_table_entry __stop___ex_table[]; extern char __end_rodata_aligned[]; +#ifdef CONFIG_NO_BOOTMEM +extern char __bootmem_start[], __bootmem_end[]; +#endif + + #if defined(CONFIG_X86_64) extern char __end_rodata_hpage_align[]; extern char __entry_trampoline_start[], __entry_trampoline_end[]; diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index b4866badb235..a4e3d9ec1a83 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -829,6 +829,17 @@ void __init setup_arch(char **cmdline_p) */ memblock_reserve(0, PAGE_SIZE); +#ifdef CONFIG_NO_BOOTMEM + /* + * There is small time window till e820__memblock_setup() is + * called, in which __bootmem_alloc() has no available memory + * to allocate and will trigger panic. Adding this revered bootmem + * can alleviate the situation. + */ + memblock_add(__pa_symbol(__bootmem_start), + __bootmem_end - __bootmem_start); +#endif + early_reserve_initrd(); /* @@ -989,7 +1000,6 @@ void __init setup_arch(char **cmdline_p) x86_report_nx(); - /* after early param, so could get panic from serial */ memblock_x86_reserve_range_setup_data(); if (acpi_mps_check()) { diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index 8bde0a419f86..fec1965d668f 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -367,6 +367,15 @@ SECTIONS __brk_limit = .; } +#ifdef CONFIG_NO_BOOTMEM + . = ALIGN(PAGE_SIZE); + .bootmem : AT(ADDR(.bootmem) - LOAD_OFFSET) { + __bootmem_start = .; + . += 128 * 1024; /* 128 KB for early boot mem */ + __bootmem_end = .; + } +#endif + . = ALIGN(PAGE_SIZE); /* keep VO_INIT_SIZE page aligned */ _end = .; -- 2.14.1