[PATCH v2 06/17] x86/ldt: Do not install LDT for kernel threads

[Peter Zijlstra <peterz@infradead.org>]

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From: Thomas Gleixner <tglx@linutronix.de>

Kernel threads can use the mm of a user process temporarily via use_mm(),
but there is no point in installing the LDT which is associated to that mm
for the kernel thread.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/include/asm/mmu_context.h |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -95,8 +95,7 @@ static inline void load_mm_ldt(struct mm
 	 * the local LDT after an IPI loaded a newer value than the one
 	 * that we can see.
 	 */
-
-	if (unlikely(ldt))
+	if (unlikely(ldt && !(current->flags & PF_KTHREAD)))
 		set_ldt(ldt->entries, ldt->nr_entries);
 	else
 		clear_LDT();


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