1 files changed, 106 insertions, 23 deletions

diff --git a/kernel/bpf/percpu_freelist.c b/kernel/bpf/percpu_freelist.c
index 6e090140b924..b6e7f5c5b9ab 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;
 }
 
@@ -25,21 +27,63 @@ void pcpu_freelist_destroy(struct pcpu_freelist *s)
 	free_percpu(s->freelist);
 }
 
+static inline void pcpu_freelist_push_node(struct pcpu_freelist_head *head,
+					   struct pcpu_freelist_node *node)
+{
+	node->next = head->first;
+	WRITE_ONCE(head->first, node);
+}
+
 static inline void ___pcpu_freelist_push(struct pcpu_freelist_head *head,
 					 struct pcpu_freelist_node *node)
 {
 	raw_spin_lock(&head->lock);
-	node->next = head->first;
-	head->first = node;
+	pcpu_freelist_push_node(head, node);
 	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 = raw_smp_processor_id();
+	while (1) {
+		for_each_cpu_wrap(cpu, cpu_possible_mask, orig_cpu) {
+			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;
+			}
+		}
+
+		/* cannot lock any per cpu lock, try extralist */
+		if (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,
@@ -56,21 +100,16 @@ void pcpu_freelist_populate(struct pcpu_freelist *s, void *buf, u32 elem_size,
 			    u32 nr_elems)
 {
 	struct pcpu_freelist_head *head;
-	unsigned long flags;
 	int i, cpu, pcpu_entries;
 
 	pcpu_entries = nr_elems / num_possible_cpus() + 1;
 	i = 0;
 
-	/* disable irq to workaround lockdep false positive
-	 * in bpf usage pcpu_freelist_populate() will never race
-	 * with pcpu_freelist_push()
-	 */
-	local_irq_save(flags);
 	for_each_possible_cpu(cpu) {
 again:
 		head = per_cpu_ptr(s->freelist, cpu);
-		___pcpu_freelist_push(head, buf);
+		/* No locking required as this is not visible yet. */
+		pcpu_freelist_push_node(head, buf);
 		i++;
 		buf += elem_size;
 		if (i == nr_elems)
@@ -78,32 +117,76 @@ again:
 		if (i % pcpu_entries)
 			goto again;
 	}
-	local_irq_restore(flags);
 }
 
-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;
-	int orig_cpu, cpu;
+	int cpu;
 
-	orig_cpu = cpu = raw_smp_processor_id();
-	while (1) {
+	for_each_cpu_wrap(cpu, cpu_possible_mask, raw_smp_processor_id()) {
 		head = per_cpu_ptr(s->freelist, cpu);
+		if (!READ_ONCE(head->first))
+			continue;
 		raw_spin_lock(&head->lock);
 		node = head->first;
 		if (node) {
-			head->first = node->next;
+			WRITE_ONCE(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)
-			return NULL;
 	}
+
+	/* per cpu lists are all empty, try extralist */
+	if (!READ_ONCE(s->extralist.first))
+		return NULL;
+	raw_spin_lock(&s->extralist.lock);
+	node = s->extralist.first;
+	if (node)
+		WRITE_ONCE(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 cpu;
+
+	for_each_cpu_wrap(cpu, cpu_possible_mask, raw_smp_processor_id()) {
+		head = per_cpu_ptr(s->freelist, cpu);
+		if (!READ_ONCE(head->first))
+			continue;
+		if (raw_spin_trylock(&head->lock)) {
+			node = head->first;
+			if (node) {
+				WRITE_ONCE(head->first, node->next);
+				raw_spin_unlock(&head->lock);
+				return node;
+			}
+			raw_spin_unlock(&head->lock);
+		}
+	}
+
+	/* cannot pop from per cpu lists, try extralist */
+	if (!READ_ONCE(s->extralist.first) || !raw_spin_trylock(&s->extralist.lock))
+		return NULL;
+	node = s->extralist.first;
+	if (node)
+		WRITE_ONCE(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)