From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756087Ab3HLXn7 (ORCPT ); Mon, 12 Aug 2013 19:43:59 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:41329 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755596Ab3HLXn5 (ORCPT ); Mon, 12 Aug 2013 19:43:57 -0400 From: Yinghai Lu To: "H. Peter Anvin" Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Dave Hansen , Yinghai Lu , Subject: [PATCH] x86: Fix booting with DEBUG_PAGE_ALLOC with more than 512G RAM Date: Mon, 12 Aug 2013 16:43:24 -0700 Message-Id: <1376351004-4015-1-git-send-email-yinghai@kernel.org> X-Mailer: git-send-email 1.8.1.4 In-Reply-To: <52090CF2.3040505@sr71.net> X-Source-IP: acsinet21.oracle.com [141.146.126.237] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dave reported that system have early crash if DEBUG_PAGEALLOC is selected, when system have between 500G and 600G. > [ 0.000000] init_memory_mapping: [mem 0x00000000-0x000fffff] > [ 0.000000] [mem 0x00000000-0x000fffff] page 4k > [ 0.000000] BRK [0x02086000, 0x02086fff] PGTABLE > [ 0.000000] BRK [0x02087000, 0x02087fff] PGTABLE > [ 0.000000] BRK [0x02088000, 0x02088fff] PGTABLE > [ 0.000000] init_memory_mapping: [mem 0xe80ee00000-0xe80effffff] > [ 0.000000] [mem 0xe80ee00000-0xe80effffff] page 4k > [ 0.000000] BRK [0x02089000, 0x02089fff] PGTABLE > [ 0.000000] BRK [0x0208a000, 0x0208afff] PGTABLE > [ 0.000000] Kernel panic - not syncing: alloc_low_page: ran out of memory It turns out that we missed increasing needed pages in BRK to mapping initial 2M and [0,1M) when we switch to use #PF handler set mem mapping. > commit 8170e6bed465b4b0c7687f93e9948aca4358a33b > Author: H. Peter Anvin > Date: Thu Jan 24 12:19:52 2013 -0800 > > x86, 64bit: Use a #PF handler to materialize early mappings on demand Before that, we have maping from [0,512M) in head_64.S, and we can spare two pages [0-1M). After that change, we can not reuse pages anymore. When we have more than 512M ram, we need extra page for pgd page with [512G, 1024g). Increase pages in BRK for page table to solve the booting problem. Reported-by: Dave Hansen Bisected-by: Dave Hansen Tested-by: Dave Hansen Signed-off-by: Yinghai Lu Cc: 3.9+ --- arch/x86/mm/init.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) Index: linux-2.6/arch/x86/mm/init.c =================================================================== --- linux-2.6.orig/arch/x86/mm/init.c +++ linux-2.6/arch/x86/mm/init.c @@ -78,8 +78,8 @@ __ref void *alloc_low_pages(unsigned int return __va(pfn << PAGE_SHIFT); } -/* need 4 4k for initial PMD_SIZE, 4k for 0-ISA_END_ADDRESS */ -#define INIT_PGT_BUF_SIZE (5 * PAGE_SIZE) +/* need 3 4k for initial PMD_SIZE, 3 4k for 0-ISA_END_ADDRESS */ +#define INIT_PGT_BUF_SIZE (6 * PAGE_SIZE) RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE); void __init early_alloc_pgt_buf(void) {