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authorSteven Capper <steve.capper@linaro.org>2013-05-16 20:16:11 +0400
committerRussell King <rmk+kernel@arm.linux.org.uk>2013-05-23 01:01:36 +0400
commit4ca46c5e1f38e32c90247686e9e17dae213ecbdb (patch)
treebb8d4b9fc8ec226f8e94f2dd2111c630bf0eb4f6
parent934fc24df10abfd5aff533d0d044a17669d77d79 (diff)
downloadlinux-4ca46c5e1f38e32c90247686e9e17dae213ecbdb.tar.xz
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 <steve.capper@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
-rw-r--r--arch/arm/kernel/process.c1
1 files changed, 0 insertions, 1 deletions
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)