1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * test_free_pages.c: Check that free_pages() doesn't leak memory
4  * Copyright (c) 2020 Oracle
5  * Author: Matthew Wilcox <willy@infradead.org>
6  */
7 
8 #define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
9 
10 #include <linux/gfp.h>
11 #include <linux/mm.h>
12 #include <linux/module.h>
13 
test_free_pages(gfp_t gfp)14 static void test_free_pages(gfp_t gfp)
15 {
16 	unsigned int i;
17 
18 	for (i = 0; i < 1000 * 1000; i++) {
19 		unsigned long addr = __get_free_pages(gfp, 3);
20 		struct page *page = virt_to_page((void *)addr);
21 
22 		/* Simulate page cache getting a speculative reference */
23 		get_page(page);
24 		free_pages(addr, 3);
25 		put_page(page);
26 	}
27 }
28 
m_in(void)29 static int m_in(void)
30 {
31 	pr_info("Testing with GFP_KERNEL\n");
32 	test_free_pages(GFP_KERNEL);
33 	pr_info("Testing with GFP_KERNEL | __GFP_COMP\n");
34 	test_free_pages(GFP_KERNEL | __GFP_COMP);
35 	pr_info("Test completed\n");
36 
37 	return 0;
38 }
39 
m_ex(void)40 static void m_ex(void)
41 {
42 }
43 
44 module_init(m_in);
45 module_exit(m_ex);
46 MODULE_AUTHOR("Matthew Wilcox <willy@infradead.org>");
47 MODULE_DESCRIPTION("Check that free_pages() doesn't leak memory");
48 MODULE_LICENSE("GPL");
49