This is a note to let you know that I've just added the patch titled

sched/core: Idle_task_exit() shouldn't use switch_mm_irqs_off()

to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: sched-core-idle_task_exit-shouldn-t-use-switch_mm_irqs_off.patch and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From 252d2a4117bc181b287eeddf848863788da733ae Mon Sep 17 00:00:00 2001

From: Andy Lutomirski luto@kernel.org Date: Fri, 9 Jun 2017 11:49:15 -0700 Subject: sched/core: Idle_task_exit() shouldn't use switch_mm_irqs_off()

From: Andy Lutomirski luto@kernel.org

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 luto@kernel.org Cc: Borislav Petkov bp@suse.de Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: stable@vger.kernel.org Fixes: f98db6013c55 ("sched/core: Add switch_mm_irqs_off() and use it in the scheduler") Link: http://lkml.kernel.org/r/ca3d1a9fa93a0b49f5a8ff729eda3640fb6abdf9.1497034141... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

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

--- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5206,7 +5206,7 @@ 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);

Patches currently in stable-queue which might be from luto@kernel.org are

queue-4.4/x86-mm-sched-core-uninline-switch_mm.patch queue-4.4/x86-mm-add-a-noinvpcid-boot-option-to-turn-off-invpcid.patch queue-4.4/x86-irq-do-not-substract-irq_tlb_count-from-irq_call_count.patch queue-4.4/x86-mm-if-invpcid-is-available-use-it-to-flush-global-mappings.patch queue-4.4/x86-mm-add-invpcid-helpers.patch queue-4.4/sched-core-add-switch_mm_irqs_off-and-use-it-in-the-scheduler.patch queue-4.4/arm-hide-finish_arch_post_lock_switch-from-modules.patch queue-4.4/x86-mm-sched-core-turn-off-irqs-in-switch_mm.patch queue-4.4/mm-mmu_context-sched-core-fix-mmu_context.h-assumption.patch queue-4.4/x86-mm-build-arch-x86-mm-tlb.c-even-on-smp.patch queue-4.4/sched-core-idle_task_exit-shouldn-t-use-switch_mm_irqs_off.patch