From: Huacai Chen Date: Sun, 17 Mar 2013 11:50:14 +0000 (+0000) Subject: MIPS: Init new mmu_context for each possible CPU to avoid memory corruption X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=224786779d04bbcd5f61eaafc86bf8fee350388a;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git MIPS: Init new mmu_context for each possible CPU to avoid memory corruption 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 Acked-by: David Daney Patchwork: http://patchwork.linux-mips.org/patch/4995/ Acked-by: John Crispin --- diff --git a/arch/mips/include/asm/mmu_context.h b/arch/mips/include/asm/mmu_context.h index e81d719efcd1..49d220ccc145 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;