From 4ca46c5e1f38e32c90247686e9e17dae213ecbdb Mon Sep 17 00:00:00 2001 From: Steven Capper Date: Thu, 16 May 2013 17:16:11 +0100 Subject: [PATCH] ARM: 7727/1: remove the .vm_mm value from gate_vma If one reads /proc/$PID/smaps, the mmap_sem belonging to the address space of the task being examined is locked for reading. All the pages of the vmas belonging to the task's address space are then walked with this lock held. If a gate_vma is present in the architecture, it too is examined by the fs/proc/task_mmu.c code. As gate_vma doesn't belong to the address space of the task though, its pages are not walked. A recent cleanup (commit f6604efe) of the gate_vma initialisation code set the vm_mm value to &init_mm. Unfortunately a non-NULL vm_mm value in the gate_vma will cause the task_mmu code to attempt to walk the pages of the gate_vma (with no mmap-sem lock held). If one enables Transparent Huge Page support and vm debugging, this will then cause OOPses as pmd_trans_huge_lock is called without mmap_sem being locked. This patch removes the .vm_mm value from gate_vma, restoring the original behaviour of the task_mmu code. Signed-off-by: Steve Capper Signed-off-by: Russell King --- arch/arm/kernel/process.c | 1 - 1 file changed, 1 deletion(-) diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c index f21970316836..282de4826abb 100644 --- a/arch/arm/kernel/process.c +++ b/arch/arm/kernel/process.c @@ -411,7 +411,6 @@ static struct vm_area_struct gate_vma = { .vm_start = 0xffff0000, .vm_end = 0xffff0000 + PAGE_SIZE, .vm_flags = VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYEXEC, - .vm_mm = &init_mm, }; static int __init gate_vma_init(void)