Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756162Ab3CQMuc (ORCPT ); Sun, 17 Mar 2013 08:50:32 -0400 Received: from mail-pb0-f51.google.com ([209.85.160.51]:65390 "EHLO mail-pb0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750955Ab3CQMub (ORCPT ); Sun, 17 Mar 2013 08:50:31 -0400 From: Huacai Chen To: Ralf Baechle Cc: linux-mips@linux-mips.org, linux-kernel@vger.kernel.org, Fuxin Zhang , Zhangjin Wu , Huacai Chen Subject: [PATCH V2 02/02] MIPS: Init new mmu_context for each possible CPU to avoid memory corruption Date: Sun, 17 Mar 2013 20:50:14 +0800 Message-Id: <1363524614-3823-1-git-send-email-chenhc@lemote.com> X-Mailer: git-send-email 1.7.7.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1471 Lines: 40 Currently, init_new_context() only for each online CPU, this may cause memory corruption when CPU hotplug and fork() happens at the same time. To avoid this, we make init_new_context() cover each possible CPU. Scenario: 1, CPU#1 is being offline; 2, On CPU#0, do_fork() call dup_mm() and copy a mm_struct to the child; 3, On CPU#0, dup_mm() call init_new_context(), since CPU#1 is offline and init_new_context() only covers the online CPUs, child has the same asid as its parent on CPU#1 (however, child's asid should be 0); 4, CPU#1 is being online; 5, Now, if both parent and child run on CPU#1, memory corruption (e.g. segfault, bus error, etc.) will occur. Signed-off-by: Huacai Chen --- arch/mips/include/asm/mmu_context.h | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/arch/mips/include/asm/mmu_context.h b/arch/mips/include/asm/mmu_context.h index e81d719..49d220c 100644 --- a/arch/mips/include/asm/mmu_context.h +++ b/arch/mips/include/asm/mmu_context.h @@ -133,7 +133,7 @@ init_new_context(struct task_struct *tsk, struct mm_struct *mm) { int i; - for_each_online_cpu(i) + for_each_possible_cpu(i) cpu_context(i, mm) = 0; return 0; -- 1.7.7.3 -- 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/