linux-mips
[Top] [All Lists]

[PATCH V2 02/02] MIPS: Init new mmu_context for each possible CPU to avo

To: Ralf Baechle <ralf@linux-mips.org>
Subject: [PATCH V2 02/02] MIPS: Init new mmu_context for each possible CPU to avoid memory corruption
From: Huacai Chen <chenhc@lemote.com>
Date: Sun, 17 Mar 2013 20:50:14 +0800
Cc: linux-mips@linux-mips.org, linux-kernel@vger.kernel.org, Fuxin Zhang <zhangfx@lemote.com>, Zhangjin Wu <wuzhangjin@gmail.com>, Huacai Chen <chenhc@lemote.com>
Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:sender:from:to:cc:subject:date:message-id:x-mailer; bh=3QMQEsWa2R036gGik8dH4ba7G/3NZjjSQ9FR4k2hK6w=; b=Wc0RGFFgMG6yoqLGWtTlDJ2eWg+lvtZwEunRRWu6xCCu1NtzBc/Zb1nFayczw6qhBb 069Ee2uth/MmtO4KKjVvO2iN82Z2/RO4/ZChLOrxoXS5HatY3Bw+Rp57e0bU/DemyacV 9gtHwiFDTEbrhkdz9hbEEj3hukmHRMtOsbTJOxnriGIN32naX8KWh3ydVude0JUx/1C/ qqNWH0FyZm/KB1uTuRQ4q66mO1hFIDyUkNXSjYbYTI1baS35s/XItD6kcy+EWaGo3hld +/WfvbwAWiArzDFynSymF5Mq2LPkInn2LGJsNmmWpprj3fdqYEM8bh2WrIq88Zqoyyky 9/Pg==
List-archive: <http://www.linux-mips.org/archives/linux-mips/>
List-help: <mailto:ecartis@linux-mips.org?Subject=help>
List-id: linux-mips <linux-mips.eddie.linux-mips.org>
List-owner: <mailto:ralf@linux-mips.org>
List-post: <mailto:linux-mips@linux-mips.org>
List-software: Ecartis version 1.0.0
List-subscribe: <mailto:ecartis@linux-mips.org?subject=subscribe%20linux-mips>
List-unsubscribe: <mailto:ecartis@linux-mips.org?subject=unsubscribe%20linux-mips>
Sender: linux-mips-bounce@linux-mips.org
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 <chenhc@lemote.com>
---
 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


<Prev in Thread] Current Thread [Next in Thread>