1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 2011-2017 Red Hat, Inc.
4 */
5
6 /*\
7 * [Description]
8 *
9 * Test for detecting mremap bug when THP is enabled.
10 *
11 * There was a bug in mremap THP support, sometimes causing crash
12 * due to the following reason:
13 *
14 * "alloc_new_pmd was forcing the allocation of a pte before calling
15 * move_huge_page and that resulted in a VM_BUG_ON in move_huge_page
16 * because the pmd wasn't zero."
17 *
18 * There are 4 cases to test this bug:
19 *
20 * 1. old_addr hpage aligned, old_end not hpage aligned, new_addr
21 * hpage aligned
22 *
23 * 2. old_addr hpage aligned, old_end not hpage aligned, new_addr not
24 * hpage aligned
25 *
26 * 3. old_addr not hpage aligned, old_end hpage aligned, new_addr
27 * hpage aligned
28 *
29 * 4. old_addr not hpage aligned, old_end hpage aligned, new_addr not
30 * hpage aligned
31 */
32
33 #define _GNU_SOURCE
34 #include "config.h"
35 #include <sys/types.h>
36 #include <sys/mman.h>
37 #include <stdio.h>
38 #include <stdlib.h>
39 #include <string.h>
40 #include <unistd.h>
41 #include "mem.h"
42
43 static int ps;
44 static long hps, size;
45
46 /*
47 * Will try to do the following 4 mremaps cases:
48 * mremap(p, size-ps, size-ps, flag, p2);
49 * mremap(p, size-ps, size-ps, flag, p2+ps);
50 * mremap(p+ps, size-ps, size-ps, flag, p2);
51 * mremap(p+ps, size-ps, size-ps, flag, p2+ps);
52 */
do_child(int i)53 static void do_child(int i)
54 {
55 long j, remap_size;
56 unsigned char *p1, *p2, *ret, *old_addr, *new_addr;
57
58 p1 = SAFE_MEMALIGN(hps, size);
59 p2 = SAFE_MEMALIGN(hps, size);
60
61 memset(p1, 0xff, size);
62 memset(p2, 0x77, size);
63
64 old_addr = p1 + ps * (i >> 1);
65 new_addr = p2 + ps * (i & 1);
66 remap_size = size - ps;
67
68 tst_res(TINFO, "mremap (%p-%p) to (%p-%p)",
69 old_addr, old_addr + remap_size,
70 new_addr, new_addr + remap_size);
71
72 ret = mremap(old_addr, remap_size, remap_size,
73 MREMAP_FIXED | MREMAP_MAYMOVE, new_addr);
74 if (ret == MAP_FAILED)
75 tst_brk(TBROK | TERRNO, "mremap");
76
77 for (j = 0; j < remap_size; j++) {
78 if (ret[j] != 0xff)
79 tst_brk(TBROK, "mremap bug");
80 }
81
82 exit(0);
83 }
84
do_mremap(void)85 static void do_mremap(void)
86 {
87 int i;
88
89 for (i = 0; i < 4; i++) {
90 if (SAFE_FORK() == 0)
91 do_child(i);
92 tst_reap_children();
93 }
94 tst_res(TPASS, "Still alive.");
95 }
96
setup(void)97 static void setup(void)
98 {
99 long memfree;
100
101 if (access(PATH_THP, F_OK) == -1)
102 tst_brk(TCONF, "THP not enabled in kernel?");
103
104 check_hugepage();
105
106 ps = sysconf(_SC_PAGESIZE);
107 hps = SAFE_READ_MEMINFO("Hugepagesize:") * 1024;
108 size = hps * 4;
109
110 memfree = (SAFE_READ_MEMINFO("MemFree:") * 1024 +
111 SAFE_READ_MEMINFO("Cached:") * 1024);
112 if (memfree < size * 2)
113 tst_brk(TCONF, "not enough memory");
114 }
115
116 static struct tst_test test = {
117 .setup = setup,
118 .test_all = do_mremap,
119 .forks_child = 1,
120 };
121