5 files changed, 25 insertions, 7 deletions

diff --git a/arch/ia64/include/asm/acpi.h b/arch/ia64/include/asm/acpi.h
index c86a947f5368..a3d0211970e9 100644
--- a/arch/ia64/include/asm/acpi.h
+++ b/arch/ia64/include/asm/acpi.h
@@ -112,6 +112,8 @@ static inline void arch_acpi_set_pdc_bits(u32 *buf)
         buf[2] |= ACPI_PDC_EST_CAPABILITY_SMP;
 }
 
+#define acpi_unlazy_tlb(x)
+
 #ifdef CONFIG_ACPI_NUMA
 extern cpumask_t early_cpu_possible_map;
 #define for_each_possible_early_cpu(cpu)  \
diff --git a/arch/x86/include/asm/acpi.h b/arch/x86/include/asm/acpi.h
index 72d867f6b518..8d0ec9df1cbe 100644
--- a/arch/x86/include/asm/acpi.h
+++ b/arch/x86/include/asm/acpi.h
@@ -150,6 +150,8 @@ static inline void disable_acpi(void) { }
 extern int x86_acpi_numa_init(void);
 #endif /* CONFIG_ACPI_NUMA */
 
+#define acpi_unlazy_tlb(x)      leave_mm(x)
+
 #ifdef CONFIG_ACPI_APEI
 static inline pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr)
 {
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 0f3d0cea4d00..3118392cdf75 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -85,6 +85,7 @@ void leave_mm(int cpu)
 
         switch_mm(NULL, &init_mm, NULL);
 }
+EXPORT_SYMBOL_GPL(leave_mm);
 
 void switch_mm(struct mm_struct *prev, struct mm_struct *next,
                struct task_struct *tsk)
@@ -195,12 +196,22 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
                         this_cpu_write(cpu_tlbstate.ctxs[new_asid].ctx_id, next->context.ctx_id);
                         this_cpu_write(cpu_tlbstate.ctxs[new_asid].tlb_gen, next_tlb_gen);
                         write_cr3(build_cr3(next, new_asid));
-                        trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH,
-                                        TLB_FLUSH_ALL);
+
+                        /*
+                         * NB: This gets called via leave_mm() in the idle path
+                         * where RCU functions differently.  Tracing normally
+                         * uses RCU, so we need to use the _rcuidle variant.
+                         *
+                         * (There is no good reason for this.  The idle code should
+                         *  be rearranged to call this before rcu_idle_enter().)
+                         */
+                        trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
                 } else {
                         /* The new ASID is already up to date. */
                         write_cr3(build_cr3_noflush(next, new_asid));
-                        trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, 0);
+
+                        /* See above wrt _rcuidle. */
+                        trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, 0);
                 }
 
                 this_cpu_write(cpu_tlbstate.loaded_mm, next);
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 2736e25e9dc6..d50a7b6ccddd 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -710,6 +710,8 @@ static DEFINE_RAW_SPINLOCK(c3_lock);
 static void acpi_idle_enter_bm(struct acpi_processor *pr,
                                struct acpi_processor_cx *cx, bool timer_bc)
 {
+        acpi_unlazy_tlb(smp_processor_id());
+
         /*
          * Must be done before busmaster disable as we might need to
          * access HPET !
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index 5dc7ea4b6bc4..f0b06b14e782 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -913,15 +913,16 @@ static __cpuidle int intel_idle(struct cpuidle_device *dev,
         struct cpuidle_state *state = &drv->states[index];
         unsigned long eax = flg2MWAIT(state->flags);
         unsigned int cstate;
+        int cpu = smp_processor_id();
 
         cstate = (((eax) >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) + 1;
 
         /*
-         * NB: if CPUIDLE_FLAG_TLB_FLUSHED is set, this idle transition
-         * will probably flush the TLB.  It's not guaranteed to flush
-         * the TLB, though, so it's not clear that we can do anything
-         * useful with this knowledge.
+         * leave_mm() to avoid costly and often unnecessary wakeups
+         * for flushing the user TLB's associated with the active mm.
          */
+        if (state->flags & CPUIDLE_FLAG_TLB_FLUSHED)
+                leave_mm(cpu);
 
         if (!(lapic_timer_reliable_states & (1 << (cstate))))
                 tick_broadcast_enter();