x86/mm: Fix RCU splat from new TLB tracepoints

Dave Jones reported seeing a bug from one of my TLB tracepoints:

        http://lkml.kernel.org/r/[email protected]

According to Paul McKenney, the right way to fix this is adding
an _rcuidle suffix to the tracepoint.

        http://lkml.kernel.org/r/[email protected]

This patch does just that.

Reported-by: Dave Jones <[email protected]>,
Signed-off-by: Dave Hansen <[email protected]>
Reviewed-by: Paul E. McKenney <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Linus Torvalds <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

Author: hansendc

arch/x86/mm/tlb.c

@@ -49,7 +49,13 @@ void leave_mm(int cpu)
 	if (cpumask_test_cpu(cpu, mm_cpumask(active_mm))) {
 		cpumask_clear_cpu(cpu, mm_cpumask(active_mm));
 		load_cr3(swapper_pg_dir);
-		trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
+		/*
+		 * This gets called in the idle path where RCU
+		 * functions differently.  Tracing normally
+		 * uses RCU, so we have to call the tracepoint
+		 * specially here.
+		 */
+		trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
 	}
 }
 EXPORT_SYMBOL_GPL(leave_mm);