1 files changed, 96 insertions, 5 deletions

diff --git a/kernel/bpf/percpu_freelist.c b/kernel/bpf/percpu_freelist.c
index b367430e611c..3d897de89061 100644
--- a/kernel/bpf/percpu_freelist.c
+++ b/kernel/bpf/percpu_freelist.c
@@ -17,6 +17,8 @@ int pcpu_freelist_init(struct pcpu_freelist *s)
 		raw_spin_lock_init(&head->lock);
 		head->first = NULL;
 	}
+	raw_spin_lock_init(&s->extralist.lock);
+	s->extralist.first = NULL;
 	return 0;
 }
 
@@ -40,12 +42,50 @@ static inline void ___pcpu_freelist_push(struct pcpu_freelist_head *head,
 	raw_spin_unlock(&head->lock);
 }
 
+static inline bool pcpu_freelist_try_push_extra(struct pcpu_freelist *s,
+						struct pcpu_freelist_node *node)
+{
+	if (!raw_spin_trylock(&s->extralist.lock))
+		return false;
+
+	pcpu_freelist_push_node(&s->extralist, node);
+	raw_spin_unlock(&s->extralist.lock);
+	return true;
+}
+
+static inline void ___pcpu_freelist_push_nmi(struct pcpu_freelist *s,
+					     struct pcpu_freelist_node *node)
+{
+	int cpu, orig_cpu;
+
+	orig_cpu = cpu = raw_smp_processor_id();
+	while (1) {
+		struct pcpu_freelist_head *head;
+
+		head = per_cpu_ptr(s->freelist, cpu);
+		if (raw_spin_trylock(&head->lock)) {
+			pcpu_freelist_push_node(head, node);
+			raw_spin_unlock(&head->lock);
+			return;
+		}
+		cpu = cpumask_next(cpu, cpu_possible_mask);
+		if (cpu >= nr_cpu_ids)
+			cpu = 0;
+
+		/* cannot lock any per cpu lock, try extralist */
+		if (cpu == orig_cpu &&
+		    pcpu_freelist_try_push_extra(s, node))
+			return;
+	}
+}
+
 void __pcpu_freelist_push(struct pcpu_freelist *s,
 			struct pcpu_freelist_node *node)
 {
-	struct pcpu_freelist_head *head = this_cpu_ptr(s->freelist);
-
-	___pcpu_freelist_push(head, node);
+	if (in_nmi())
+		___pcpu_freelist_push_nmi(s, node);
+	else
+		___pcpu_freelist_push(this_cpu_ptr(s->freelist), node);
 }
 
 void pcpu_freelist_push(struct pcpu_freelist *s,
@@ -81,7 +121,7 @@ again:
 	}
 }
 
-struct pcpu_freelist_node *__pcpu_freelist_pop(struct pcpu_freelist *s)
+static struct pcpu_freelist_node *___pcpu_freelist_pop(struct pcpu_freelist *s)
 {
 	struct pcpu_freelist_head *head;
 	struct pcpu_freelist_node *node;
@@ -102,8 +142,59 @@ struct pcpu_freelist_node *__pcpu_freelist_pop(struct pcpu_freelist *s)
 		if (cpu >= nr_cpu_ids)
 			cpu = 0;
 		if (cpu == orig_cpu)
-			return NULL;
+			break;
+	}
+
+	/* per cpu lists are all empty, try extralist */
+	raw_spin_lock(&s->extralist.lock);
+	node = s->extralist.first;
+	if (node)
+		s->extralist.first = node->next;
+	raw_spin_unlock(&s->extralist.lock);
+	return node;
+}
+
+static struct pcpu_freelist_node *
+___pcpu_freelist_pop_nmi(struct pcpu_freelist *s)
+{
+	struct pcpu_freelist_head *head;
+	struct pcpu_freelist_node *node;
+	int orig_cpu, cpu;
+
+	orig_cpu = cpu = raw_smp_processor_id();
+	while (1) {
+		head = per_cpu_ptr(s->freelist, cpu);
+		if (raw_spin_trylock(&head->lock)) {
+			node = head->first;
+			if (node) {
+				head->first = node->next;
+				raw_spin_unlock(&head->lock);
+				return node;
+			}
+			raw_spin_unlock(&head->lock);
+		}
+		cpu = cpumask_next(cpu, cpu_possible_mask);
+		if (cpu >= nr_cpu_ids)
+			cpu = 0;
+		if (cpu == orig_cpu)
+			break;
 	}
+
+	/* cannot pop from per cpu lists, try extralist */
+	if (!raw_spin_trylock(&s->extralist.lock))
+		return NULL;
+	node = s->extralist.first;
+	if (node)
+		s->extralist.first = node->next;
+	raw_spin_unlock(&s->extralist.lock);
+	return node;
+}
+
+struct pcpu_freelist_node *__pcpu_freelist_pop(struct pcpu_freelist *s)
+{
+	if (in_nmi())
+		return ___pcpu_freelist_pop_nmi(s);
+	return ___pcpu_freelist_pop(s);
 }
 
 struct pcpu_freelist_node *pcpu_freelist_pop(struct pcpu_freelist *s)