sched/debug: Add taint on "BUG: Sleeping function called from invalid context"

Seeing this, it occurs to me that we should probably add a taint here:

    BUG: sleeping function called from invalid context at mm/slab.h:388
    in_atomic(): 0, irqs_disabled(): 0, pid: 32211, name: trinity-c3
    Preemption disabled at:[<ffffffff811aaa37>] console_unlock+0x2f7/0x930

    CPU: 3 PID: 32211 Comm: trinity-c3 Not tainted 4.7.0-rc7+ #19
                                       ^^^^^^^^^^^
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
     0000000000000000 ffff8800b8a17160 ffffffff81971441 ffff88011a3c4c80
     ffff88011a3c4c80 ffff8800b8a17198 ffffffff81158067 0000000000000de6
     ffff88011a3c4c80 ffffffff8390e07c 0000000000000184 0000000000000000
    Call Trace:
    [...]

    BUG: sleeping function called from invalid context at arch/x86/mm/fault.c:1309
    in_atomic(): 0, irqs_disabled(): 0, pid: 32211, name: trinity-c3
    Preemption disabled at:[<ffffffff8119db33>] down_trylock+0x13/0x80

    CPU: 3 PID: 32211 Comm: trinity-c3 Not tainted 4.7.0-rc7+ #19
                                       ^^^^^^^^^^^
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
     0000000000000000 ffff8800b8a17e08 ffffffff81971441 ffff88011a3c4c80
     ffff88011a3c4c80 ffff8800b8a17e40 ffffffff81158067 0000000000000000
     ffff88011a3c4c80 ffffffff83437b20 000000000000051d 0000000000000000
    Call Trace:
    [...]

Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rusty Russel <rusty@rustcorp.com.au>
Link: http://lkml.kernel.org/r/1469216762-19626-1-git-send-email-vegard.nossum@oracle.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/core.c

@@ -7608,6 +7608,7 @@ void ___might_sleep(const char *file, int line, int preempt_offset)
 		pr_cont("\n");
 	}
 	dump_stack();
+	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
 }
 EXPORT_SYMBOL(___might_sleep);
 #endif