diff --git arch/x86_64/kernel/include/syscall_list.h arch/x86_64/kernel/include/syscall_list.h
index 48b1ea0..a752a7e 100644
--- arch/x86_64/kernel/include/syscall_list.h
+++ arch/x86_64/kernel/include/syscall_list.h
@@ -161,6 +161,7 @@ SYSCALL_HANDLED(__NR_profile, profile)
 SYSCALL_HANDLED(730, util_migrate_inter_kernel)
 SYSCALL_HANDLED(731, util_indicate_clone)
 SYSCALL_HANDLED(732, get_system)
+SYSCALL_HANDLED(733, get_mem_info)
 
 /* McKernel Specific */
 SYSCALL_HANDLED(801, swapout)
diff --git kernel/mem.c kernel/mem.c
index f6dc309..cdd7928 100644
--- kernel/mem.c
+++ kernel/mem.c
@@ -1608,6 +1608,9 @@ int page_unmap(struct page *page)
 		return 1;
 	}
 	*/
+	if(ihk_atomic_read(&page->count) < 0) {
+		kprintf("page_unmap: BAD count\n");
+	}
 
 	dkprintf("page_unmap(%p %x %d): 1\n", page, page->mode, page->count);
 	list_del(&page->hash);
@@ -2540,3 +2543,31 @@ int ihk_mc_get_mem_user_page(void *arg0, page_table_t pt, pte_t *ptep, void *pga
 
 	return 0;
 }
+
+void dbg_page_count(int init)
+{
+
+	int i;
+	struct page *page_iter;
+	unsigned long irqflags;
+	int cnt = 0;
+	int bad = 0;
+
+	for (i = 0; i < PHYS_PAGE_HASH_SIZE; i++) {
+		irqflags = ihk_mc_spinlock_lock(&page_hash_locks[i]);
+		list_for_each_entry(page_iter, &page_hash[i], hash) {
+			cnt++;
+			if (ihk_atomic_read(&page_iter->count) < 0)
+				bad++;
+		}
+		ihk_mc_spinlock_unlock(&page_hash_locks[i], irqflags);
+	}
+
+	if (init || bad) {
+		if (!bad)
+			kprintf("struct page # = %d\n", cnt);
+		else
+			kprintf("struct page # = %d, bad # = %d\n", cnt, bad);
+	}
+}
+
diff --git kernel/process.c kernel/process.c
index bb15608..25daa0e 100644
--- kernel/process.c
+++ kernel/process.c
@@ -95,6 +95,7 @@ extern void procfs_delete_thread(struct thread *);
 extern void perf_start(struct mc_perf_event *event);
 extern void perf_reset(struct mc_perf_event *event);
 #endif /* !POSTK_DEBUG_ARCH_DEP_22 */
+extern void dbg_page_count(int) ;
 
 struct list_head resource_set_list;
 mcs_rwlock_lock_t    resource_set_lock;
@@ -2769,6 +2770,8 @@ static void idle(void)
 		v->status = CPU_STATUS_IDLE;
 	cpu_enable_interrupt();
 
+	dbg_page_count(1);
+
 	while (1) {
 		cpu_local_var(current)->status = PS_STOPPED;
 		schedule();
@@ -3304,6 +3307,8 @@ redo:
 
 		if ((last != NULL) && (last->status == PS_EXITED)) {
 			release_thread(last);
+
+			dbg_page_count(0);
 		}
 
 		/* Have we migrated to another core meanwhile? */
diff --git kernel/syscall.c kernel/syscall.c
index d51cdeb..1073060 100644
--- kernel/syscall.c
+++ kernel/syscall.c
@@ -9186,6 +9186,35 @@ SYSCALL_DECLARE(resume_threads)
 	return 0;
 }
 
+SYSCALL_DECLARE(get_mem_info)
+{
+	unsigned long addr = ihk_mc_syscall_arg0(ctx);
+	struct thread *thread = cpu_local_var(current);
+	struct vm_range *range = lookup_process_memory_range(thread->vm,
+	                                                     addr, addr + 1);
+	struct process_vm *vm = thread->vm;
+	pte_t *ptep;
+	void *pgaddr;
+	size_t pgsize;
+	int p2align;
+	struct page *page = NULL;
+
+	if (!range)
+		return -EINVAL;
+
+	ihk_mc_spinlock_lock_noirq(&vm->page_table_lock);
+	ptep = ihk_mc_pt_lookup_pte(vm->address_space->page_table,
+		(void *)addr, range->pgshift, &pgaddr, &pgsize, &p2align);
+	if (ptep && !pte_is_null(ptep) && !pte_is_fileoff(ptep, pgsize)) {
+		unsigned long phys;
+		phys = pte_get_phys(ptep);
+		page = phys_to_page(phys);
+	}
+
+	ihk_mc_spinlock_unlock_noirq(&vm->page_table_lock);
+	return pgsize | (page ? 1 : 0);
+}
+
 void
 reset_cputime()
 {