1 // SPDX-License-Identifier: LGPL-2.1-or-later
2 /*
3 * Copyright (C) 2005-2006 IBM Corporation.
4 * Author: Mel Gorman
5 */
6
7 /*\
8 * [Description]
9 *
10 * readahead() on some kernels can cause the reservation counter to get
11 * corrupted. The problem is that the pages are allocated for the
12 * reservation but not faulted in at the time of allocation. The
13 * counters do not get updated and effectively "leak". This test
14 * identifies whether the kernel is vulnerable to the problem or not.
15 * It's fixed in kernel by commit f2deae9d4e70.
16 */
17
18 #define _GNU_SOURCE
19 #include "hugetlb.h"
20
21 #define MNTPOINT "hugetlbfs/"
22 static long hpage_size;
23 static int fd = -1;
24
run_test(void)25 static void run_test(void)
26 {
27 void *p;
28 unsigned long initial_rsvd, map_rsvd, readahead_rsvd, end_rsvd;
29
30 fd = tst_creat_unlinked(MNTPOINT, 0);
31 initial_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
32
33 p = SAFE_MMAP(NULL, hpage_size, PROT_READ|PROT_WRITE, MAP_SHARED,
34 fd, 0);
35 map_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
36 tst_res(TINFO, "map_rsvd: %lu", map_rsvd);
37
38 readahead(fd, 0, hpage_size);
39 readahead_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
40 tst_res(TINFO, "readahead_rsvd: %lu", readahead_rsvd);
41
42 memset(p, 1, hpage_size);
43
44 SAFE_MUNMAP(p, hpage_size);
45 SAFE_CLOSE(fd);
46 end_rsvd = SAFE_READ_MEMINFO(MEMINFO_HPAGE_RSVD);
47
48 TST_EXP_EQ_LU(end_rsvd, initial_rsvd);
49 }
50
setup(void)51 static void setup(void)
52 {
53 hpage_size = tst_get_hugepage_size();
54 }
55
cleanup(void)56 static void cleanup(void)
57 {
58 if (fd >= 0)
59 SAFE_CLOSE(fd);
60 }
61
62 static struct tst_test test = {
63 .tags = (struct tst_tag[]) {
64 {"linux-git", "f2deae9d4e70"},
65 {}
66 },
67 .needs_root = 1,
68 .mntpoint = MNTPOINT,
69 .needs_hugetlbfs = 1,
70 .needs_tmpdir = 1,
71 .setup = setup,
72 .cleanup = cleanup,
73 .test_all = run_test,
74 .hugepages = {1, TST_NEEDS},
75 };
76