Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752391Ab3EIQLq (ORCPT ); Thu, 9 May 2013 12:11:46 -0400 Received: from mail-pd0-f175.google.com ([209.85.192.175]:51674 "EHLO mail-pd0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751048Ab3EIQLp (ORCPT ); Thu, 9 May 2013 12:11:45 -0400 From: Jiang Liu To: Andrew Morton Cc: Jiang Liu , EUNBONG SONG , David Daney , Ralf Baechle , Arnd Bergmann , linux-mips@linux-mips.org, linux-kernel@vger.kernel.org Subject: [PATCH] mm, MIPS: fix a bug caused by free_initmem_default() Date: Fri, 10 May 2013 00:10:04 +0800 Message-Id: <1368115804-22220-1-git-send-email-jiang.liu@huawei.com> X-Mailer: git-send-email 1.7.9.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3939 Lines: 90 EUNBONG SONG reported a bug on MIPS64 platforms caused by free_initmem() as below: [ 132.134719] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W 3.9.0+ #29 [ 132.141678] Stack : 0000000000000004 000000000000003f ffffffff80fa0000 ffffffff802924a8 0000000000000000 ffffffff80fa0000 00000000000000ff ffffffff80293760 0000000000000000 0000000000000000 ffffffff81080000 ffffffff81080000 ffffffff80e2baf0 ffffffff80f93977 a80000004146cbb8 0000000000000020 0000000000000003 0000000000000020 a800000041473da8 ffffffff810f0000 a800000041473a10 ffffffff806ef910 a800000041473828 ffffffff80290920 0000000000000000 ffffffff80293b90 000000000000000a ffffffff80e2baf0 0000000000000000 a800000041473750 000000004146cef8 ffffffff805e7794 0000000000000000 0000000000000000 0000000000000000 0000000000000000 0000000000000000 ffffffff80272498 0000000000000000 0000000000000000 ... [ 132.207201] Call Trace: [ 132.209655] [] show_stack+0x68/0x80 [ 132.225943] [] notifier_call_chain+0x5c/0xa8 [ 132.231776] [] __atomic_notifier_call_chain+0x3c/0x58 [ 132.238391] [] notify_die+0x38/0x48 [ 132.243442] [] die+0x4c/0x148 [ 132.247974] [] do_page_fault+0x4b8/0x500 [ 132.253461] [] resume_userspace_check+0x0/0x10 [ 132.259469] [] free_reserved_area+0x8c/0x178 [ 132.265304] [] kernel_init+0x20/0x100 [ 132.270529] [] ret_from_kernel_thread+0x10/0x18 The root cause is that virt_to_page()/virt_to_phys() can't be used to handle virtual address from compatible segments on MIPS64 because virt_to_phys() is defined as: static inline unsigned long virt_to_phys(volatile const void *address) { return (unsigned long)address - PAGE_OFFSET + PHYS_OFFSET; } x86_64 platforms have a similar situation, but __pa() has been enhanced to handle virtual address space used for kernel code and data segments. static inline unsigned long __phys_addr_nodebug(unsigned long x) { unsigned long y = x - __START_KERNEL_map; /* use the carry flag to determine if x was < __START_KERNEL_map */ x = y + ((x > y) ? phys_base : (__START_KERNEL_map - PAGE_OFFSET)); return x; } So we have two possible solutions here. The quick solution is to revert to the original implementation by using __pa_symbal(). The long term solution is to enhance virt_to_phys() to correctly handle virtual address from compatible segments. This patch adopts the quick solution to fix the bug for v3.10, and we need guidance from MIPS64 experts on whether we should go with the long term solution. Signed-off-by: Jiang Liu Signed-off-by: EUNBONG SONG Cc: David Daney Cc: Ralf Baechle Cc: Andrew Morton Cc: Arnd Bergmann Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org --- arch/mips/mm/init.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c index 3d0346d..3648768 100644 --- a/arch/mips/mm/init.c +++ b/arch/mips/mm/init.c @@ -446,7 +446,9 @@ void free_initrd_mem(unsigned long start, unsigned long end) void __init_refok free_initmem(void) { prom_free_prom_memory(); - free_initmem_default(POISON_FREE_INITMEM); + free_init_pages("unused kernel memory", + __pa_symbol(&__init_begin), + __pa_symbol(&__init_end)); } #ifndef CONFIG_MIPS_PGD_C0_CONTEXT -- 1.7.9.5 -- 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/