Commit 57f60202 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcutorture: Properly synchronize with OOM notifier 



The current rcutorture forward-progress code assumes that it is the
only cause of out-of-memory (OOM) events.  For script-based rcutorture
testing, this assumption is in fact correct.  However, testing based
on modprobe/rmmod might well encounter external OOM events, which could
happen at any time.

This commit therefore properly synchronizes the interaction between
rcutorture's forward-progress testing and its OOM notifier by adding a
global mutex.

Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent c8fa6371

kernel/rcu/rcutorture.c

+13 −1
Original line number Diff line number Diff line
@@ -1796,6 +1796,7 @@ struct rcu_fwd { 
	unsigned long rcu_launder_gp_seq_start;

};



static DEFINE_MUTEX(rcu_fwd_mutex);

static struct rcu_fwd *rcu_fwds;

static bool rcu_fwd_emergency_stop;
@@ -2062,8 +2063,14 @@ static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp) 
static int rcutorture_oom_notify(struct notifier_block *self,

				 unsigned long notused, void *nfreed)

{

	struct rcu_fwd *rfp = rcu_fwds;

	struct rcu_fwd *rfp;



	mutex_lock(&rcu_fwd_mutex);

	rfp = rcu_fwds;

	if (!rfp) {

		mutex_unlock(&rcu_fwd_mutex);

		return NOTIFY_OK;

	}

	WARN(1, "%s invoked upon OOM during forward-progress testing.\n",

	     __func__);

	rcu_torture_fwd_cb_hist(rfp);
@@ -2081,6 +2088,7 @@ static int rcutorture_oom_notify(struct notifier_block *self, 
	smp_mb(); /* Frees before return to avoid redoing OOM. */

	(*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */

	pr_info("%s returning after OOM processing.\n", __func__);

	mutex_unlock(&rcu_fwd_mutex);

	return NOTIFY_OK;

}
@@ -2148,7 +2156,9 @@ static int __init rcu_torture_fwd_prog_init(void) 
		return -ENOMEM;

	spin_lock_init(&rfp->rcu_fwd_lock);

	rfp->rcu_fwd_cb_tail = &rfp->rcu_fwd_cb_head;

	mutex_lock(&rcu_fwd_mutex);

	rcu_fwds = rfp;

	mutex_unlock(&rcu_fwd_mutex);

	return torture_create_kthread(rcu_torture_fwd_prog, rfp, fwd_prog_task);

}
@@ -2158,7 +2168,9 @@ static void rcu_torture_fwd_prog_cleanup(void) 


	torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task);

	rfp = rcu_fwds;

	mutex_lock(&rcu_fwd_mutex);

	rcu_fwds = NULL;

	mutex_unlock(&rcu_fwd_mutex);

	kfree(rfp);

}

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