diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index dc9301d..15f5a71 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -709,6 +709,7 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
 
 	/* No owner, become one */
 	dev->mm = get_task_mm(current);
+	debug_mm = dev->mm;
 	worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
 	if (IS_ERR(worker)) {
 		err = PTR_ERR(worker);
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index a3fda9f..fa7f5d0 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -9,6 +9,7 @@
 #include <linux/gfp.h>
 #include <linux/sync_core.h>
 
+static struct mm_struct *debug_mm;
 /*
  * Routines for handling mm_structs
  */
@@ -33,6 +34,10 @@
  */
 static inline void mmgrab(struct mm_struct *mm)
 {
+	if (debug_mm == mm) {
+		printk("mmgrab %p\n", mm);
+		dump_stack();
+	}
 	atomic_inc(&mm->mm_count);
 }
 
@@ -45,6 +50,10 @@ static inline void mmdrop(struct mm_struct *mm)
 	 * required by the membarrier system call before returning to
 	 * user-space, after storing to rq->curr.
 	 */
+	if (debug_mm == mm) {
+		printk("mmdrop %p before %d\n", mm, atomic_read(&mm->mm_count));
+		dump_stack();
+	}
 	if (unlikely(atomic_dec_and_test(&mm->mm_count)))
 		__mmdrop(mm);
 }
@@ -88,11 +97,19 @@ static inline bool mmget_still_valid(struct mm_struct *mm)
  */
 static inline void mmget(struct mm_struct *mm)
 {
+	if (debug_mm == mm) {
+		printk("mget %p\n", mm);
+		dump_stack();
+	}
 	atomic_inc(&mm->mm_users);
 }
 
 static inline bool mmget_not_zero(struct mm_struct *mm)
 {
+	if (debug_mm == mm) {
+		printk("mmget_not_zero %p\n", mm);
+		dump_stack();
+	}
 	return atomic_inc_not_zero(&mm->mm_users);
 }
 
diff --git a/kernel/fork.c b/kernel/fork.c
index b2b87d4..9a4e5d6 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1076,6 +1076,10 @@ void mmput(struct mm_struct *mm)
 {
 	might_sleep();
 
+	if (debug_mm == mm) {
+		printk("mmput mm %p before %d\n", mm, atomic_read(&mm->mm_users));
+		dump_stack();
+	}
 	if (atomic_dec_and_test(&mm->mm_users))
 		__mmput(mm);
 }
@@ -1092,6 +1096,10 @@ static void mmput_async_fn(struct work_struct *work)
 
 void mmput_async(struct mm_struct *mm)
 {
+	if (debug_mm == mm) {
+		printk("mmput mm %p before %d\n", mm, atomic_read(&mm->mm_users));
+		dump_stack();
+	}
 	if (atomic_dec_and_test(&mm->mm_users)) {
 		INIT_WORK(&mm->async_put_work, mmput_async_fn);
 		schedule_work(&mm->async_put_work);