Steven,

This warning happens on tip/master and is at least not a recent regression.

        if (!hardirq_count()) {
                if (softirq_count()) {
                        /* like the above, but with softirqs */
==>                     DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
                } else {

[  122.608332] Testing tracer function: 
[  259.757224] ------------[ cut here ]------------
[  259.759189] WARNING: at /c/kernel-tests/src/linux/kernel/lockdep.c:3506 check_flags+0x126/0x158()
[  259.759345] Hardware name: Bochs
[  259.759345] Pid: 1, comm: swapper/0 Not tainted 3.6.0-rc3-01656-gbddd486 #88
[  259.759345] Call Trace:
[  259.759345]  [<c103461f>] warn_slowpath_common+0x77/0x8c
[  259.759345]  [<c1075edd>] ? check_flags+0x126/0x158
[  259.759345]  [<c1075edd>] ? check_flags+0x126/0x158
[  259.759345]  [<c10346dd>] warn_slowpath_null+0x22/0x25
[  259.759345]  [<c1075edd>] check_flags+0x126/0x158
[  259.759345]  [<c1076c27>] lock_is_held+0x28/0x82
[  259.759345]  [<c105e34c>] ? sub_preempt_count+0x4/0x39
[  259.759345]  [<c103b344>] ? __local_bh_enable+0x86/0x89
[  259.759345]  [<c1096556>] rcu_read_lock_held+0x33/0x35
[  259.759345]  [<c109671e>] ftrace_ops_no_ops+0x80/0xb4
[  259.759345]  [<c103b709>] ? local_bh_enable_ip+0xf/0xf
[  259.759345]  [<c190de11>] trace+0x13/0x1b
[  259.759345]  [<c105e351>] ? sub_preempt_count+0x9/0x39
[  259.759345]  [<c103b344>] __local_bh_enable+0x86/0x89
[  259.759345]  [<c103b8e0>] __do_softirq+0x1d7/0x235
[  259.759345]  [<c103b709>] ? local_bh_enable_ip+0xf/0xf
[  259.759345]  <IRQ>  [<c103ba3f>] ? irq_exit+0x4f/0x7f
[  259.759345]  [<c1003afe>] ? do_IRQ+0x7e/0x92
[  259.759345]  [<c10763ec>] ? trace_hardirqs_off_caller+0xa3/0x115
[  259.759345]  [<c190ddce>] ? common_interrupt+0x2e/0x34
[  259.759345]  [<c107dad4>] ? arch_local_irq_restore+0x5/0xb
[  259.759345]  [<c190c6ea>] ? _raw_spin_unlock_irqrestore+0x44/0x67
[  259.759345]  [<c1333b59>] ? __debug_object_init+0x25c/0x264
[  259.759345]  [<c1096556>] ? rcu_read_lock_held+0x33/0x35
[  259.759345]  [<c1333b8c>] ? debug_object_init_on_stack+0x16/0x18
[  259.759345]  [<c104156b>] ? init_timer_on_stack_key+0x1c/0x56
[  259.759345]  [<c190a539>] ? schedule_timeout+0x60/0xa5
[  259.759345]  [<c190a5b9>] ? schedule_timeout_uninterruptible+0x3/0x1c
[  259.759345]  [<c1041dc4>] ? msleep+0x15/0x1b
[  259.759345]  [<c1096556>] ? rcu_read_lock_held+0x33/0x35
[  259.759345]  [<c109671e>] ? ftrace_ops_no_ops+0x80/0xb4
[  259.759345]  [<c190de11>] ? trace+0x13/0x1b
[  259.759345]  [<c190a5d0>] ? schedule_timeout_uninterruptible+0x1a/0x1c
[  259.759345]  [<c1041dc4>] ? msleep+0x15/0x1b
[  259.759345]  [<c109ea01>] ? trace_selftest_startup_function+0x6f/0x17e
[  259.759345]  [<c18f7861>] ? printk+0x3d/0x3f
[  259.759345]  [<c109f41e>] ? register_tracer+0x130/0x213
[  259.759345]  [<c1d9e0c8>] ? init_trace_printk_function_export+0x33/0x33
[  259.759345]  [<c1d9e0d5>] ? init_function_trace+0xd/0xf
[  259.759345]  [<c1d87a1b>] ? do_one_initcall+0x7f/0x12f
[  259.759345]  [<c1d87bdf>] ? kernel_init+0x114/0x1ab
[  259.759345]  [<c1d873bb>] ? loglevel+0x2b/0x2b
[  259.759345]  [<c1d87acb>] ? do_one_initcall+0x12f/0x12f
[  259.759345]  [<c190ddda>] ? kernel_thread_helper+0x6/0x10

Thanks,
Fengguang