Commit a2ab1e45 authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Uladzislau Rezki (Sony)
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rcutorture: Ignore attempts to test preemption and forward progress 



Use of the rcutorture preempt_duration and the default-on fwd_progress
kernel parameters can result in preemption of callback processing during
forward-progress testing, which is an excellent way to OOM your test
if your kernel offloads RCU callbacks.  This commit therefore treats
preempt_duration in the same way as stall_cpu in CONFIG_RCU_NOCB_CPU=y
kernels, prohibiting fwd_progress testing and splatting when rcutorture
is built in (as opposed to being a loadable module).

Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Signed-off-by: default avatarUladzislau Rezki (Sony) <urezki@gmail.com>
parent ec9d6356

kernel/rcu/rcutorture.c

+3 −3
Original line number Diff line number Diff line
@@ -3145,12 +3145,12 @@ static int __init rcu_torture_fwd_prog_init(void) 
		fwd_progress = 0;

		return 0;

	}

	if (stall_cpu > 0) {

		VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, conflicts with CPU-stall testing");

	if (stall_cpu > 0 || (preempt_duration > 0 && IS_ENABLED(CONFIG_RCU_NOCB_CPU))) {

		VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, conflicts with CPU-stall and/or preemption testing");

		fwd_progress = 0;

		if (IS_MODULE(CONFIG_RCU_TORTURE_TEST))

			return -EINVAL; /* In module, can fail back to user. */

		WARN_ON(1); /* Make sure rcutorture notices conflict. */

		WARN_ON(1); /* Make sure rcutorture scripting notices conflict. */

		return 0;

	}

	if (fwd_progress_holdoff <= 0)