Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756233Ab0KWScl (ORCPT ); Tue, 23 Nov 2010 13:32:41 -0500 Received: from [69.28.251.93] ([69.28.251.93]:48870 "EHLO b32.net" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1754342Ab0KWSck (ORCPT ); Tue, 23 Nov 2010 13:32:40 -0500 From: Kevin Cernekee To: Ralf Baechle Cc: , Subject: [PATCH RESEND 2/7] MIPS: pfn_valid() is broken on low memory HIGHMEM systems Date: Tue, 23 Nov 2010 10:26:40 -0800 Message-Id: <48048c96a59422807068107fe4a25bae@localhost> In-Reply-To: <8a8eee995454c8b271cceb440e31699a@localhost> References: <8a8eee995454c8b271cceb440e31699a@localhost> User-Agent: vim 7.2 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1640 Lines: 50 pfn_valid() compares the PFN to max_mapnr: __pfn >= min_low_pfn && __pfn < max_mapnr; On HIGHMEM kernels, highend_pfn is used to set the value of max_mapnr. Unfortunately, highend_pfn is left at zero if the system does not actually have enough RAM to reach into the HIGHMEM range. This causes pfn_valid() to always return false, and when debug checks are enabled the kernel will fail catastrophically: Memory: 22432k/32768k available (2249k kernel code, 10336k reserved, 653k data, 1352k init, 0k highmem) NR_IRQS:128 kfree_debugcheck: out of range ptr 81c02900h. Kernel bug detected[#1]: Cpu 0 $ 0 : 00000000 10008400 00000034 00000000 $ 4 : 8003e160 802a0000 8003e160 00000000 $ 8 : 00000000 0000003e 00000747 00000747 ... On such a configuration, max_low_pfn should be used to set max_mapnr. This was seen on 2.6.34. Signed-off-by: Kevin Cernekee --- arch/mips/mm/init.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c index 2efcbd2..18183a4 100644 --- a/arch/mips/mm/init.c +++ b/arch/mips/mm/init.c @@ -370,7 +370,7 @@ void __init mem_init(void) #ifdef CONFIG_DISCONTIGMEM #error "CONFIG_HIGHMEM and CONFIG_DISCONTIGMEM dont work together yet" #endif - max_mapnr = highend_pfn; + max_mapnr = highend_pfn ? : max_low_pfn; #else max_mapnr = max_low_pfn; #endif -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/