diff --git a/lib/percpu-rwlock.c b/lib/percpu-rwlock.c
index bf95e40..64ccd3f 100644
--- a/lib/percpu-rwlock.c
+++ b/lib/percpu-rwlock.c
@@ -50,6 +50,12 @@
 	(__this_cpu_read((pcpu_rwlock)->rw_state->writer_signal))
 
 
+/*
+ * Spinlock to synchronize access to the writer's data-structures
+ * (->writer_signal) from multiple writers.
+ */
+static DEFINE_SPINLOCK(writer_side_lock);
+
 int __percpu_init_rwlock(struct percpu_rwlock *pcpu_rwlock,
 			 const char *name, struct lock_class_key *rwlock_key)
 {
@@ -191,6 +197,8 @@ void percpu_write_lock_irqsave(struct percpu_rwlock *pcpu_rwlock,
 {
 	unsigned int cpu;
 
+	spin_lock(&writer_side_lock);
+
 	/*
 	 * Tell all readers that a writer is becoming active, so that they
 	 * start switching over to the global rwlock.
@@ -252,5 +260,6 @@ void percpu_write_unlock_irqrestore(struct percpu_rwlock *pcpu_rwlock,
 		per_cpu_ptr(pcpu_rwlock->rw_state, cpu)->writer_signal = false;
 
 	write_unlock_irqrestore(&pcpu_rwlock->global_rwlock, *flags);
+	spin_unlock(&writer_side_lock);
 }