4.11-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andy Lutomirski <[email protected]>

commit 252d2a4117bc181b287eeddf848863788da733ae upstream.

idle_task_exit() can be called with IRQs on x86 on and therefore
should use switch_mm(), not switch_mm_irqs_off().

This doesn't seem to cause any problems right now, but it will
confuse my upcoming TLB flush changes.  Nonetheless, I think it
should be backported because it's trivial.  There won't be any
meaningful performance impact because idle_task_exit() is only
used when offlining a CPU.

Signed-off-by: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Fixes: f98db6013c55 ("sched/core: Add switch_mm_irqs_off() and use it in the 
scheduler")
Link: 
http://lkml.kernel.org/r/ca3d1a9fa93a0b49f5a8ff729eda3640fb6abdf9.1497034141.git.l...@kernel.org
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 kernel/sched/core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5533,7 +5533,7 @@ void idle_task_exit(void)
        BUG_ON(cpu_online(smp_processor_id()));
 
        if (mm != &init_mm) {
-               switch_mm_irqs_off(mm, &init_mm, current);
+               switch_mm(mm, &init_mm, current);
                finish_arch_post_lock_switch();
        }
        mmdrop(mm);


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