sched: Taint kernel with TAINT_WARN after sleep-in-atomic bug

Usually sleep-in-atomic bugs are followed by dozens other warnings.
This patch should help to figure out original source of problem.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120510122004.4873.12726.stgit@zurg
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 24ca677..ab9745f 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3138,6 +3138,7 @@
 	if (irqs_disabled())
 		print_irqtrace_events(prev);
 	dump_stack();
+	add_taint(TAINT_WARN);
 }
 
 /*