1 /*
2 * Copyright (C) 2011-2017 Red Hat, Inc.
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
12 * the GNU General Public License for more details.
13 */
14
15 /* thp02 - detect mremap bug when THP is enabled.
16 *
17 * There was a bug in mremap THP support, sometimes crash happened
18 * due to the following reason according to developers:
19 *
20 * "alloc_new_pmd was forcing the allocation of a pte before calling
21 * move_huge_page and that resulted in a VM_BUG_ON in move_huge_page
22 * because the pmd wasn't zero."
23 *
24 * There are 4 cases to test this bug:
25 *
26 * 1) old_addr hpage aligned, old_end not hpage aligned, new_addr
27 * hpage aligned;
28 * 2) old_addr hpage aligned, old_end not hpage aligned, new_addr not
29 * hpage aligned;
30 * 3) old_addr not hpage aligned, old_end hpage aligned, new_addr
31 * hpage aligned;
32 * 4) old_addr not hpage aligned, old_end hpage aligned, new_addr not
33 * hpage aligned.
34 *
35 */
36
37 #define _GNU_SOURCE
38 #include "config.h"
39 #include <sys/types.h>
40 #include <sys/mman.h>
41 #include <stdio.h>
42 #include <stdlib.h>
43 #include <string.h>
44 #include <unistd.h>
45 #include "mem.h"
46
47 #ifdef HAVE_MREMAP_FIXED
48 static int ps;
49 static long hps, size;
50
51 /*
52 * Will try to do the following 4 mremaps cases:
53 * mremap(p, size-ps, size-ps, flag, p2);
54 * mremap(p, size-ps, size-ps, flag, p2+ps);
55 * mremap(p+ps, size-ps, size-ps, flag, p2);
56 * mremap(p+ps, size-ps, size-ps, flag, p2+ps);
57 */
do_child(int i)58 static void do_child(int i)
59 {
60 long j, remap_size;
61 unsigned char *p1, *p2, *ret, *old_addr, *new_addr;
62
63 p1 = SAFE_MEMALIGN(hps, size);
64 p2 = SAFE_MEMALIGN(hps, size);
65
66 memset(p1, 0xff, size);
67 memset(p2, 0x77, size);
68
69 old_addr = p1 + ps * (i >> 1);
70 new_addr = p2 + ps * (i & 1);
71 remap_size = size - ps;
72
73 tst_res(TINFO, "mremap (%p-%p) to (%p-%p)",
74 old_addr, old_addr + remap_size,
75 new_addr, new_addr + remap_size);
76
77 ret = mremap(old_addr, remap_size, remap_size,
78 MREMAP_FIXED | MREMAP_MAYMOVE, new_addr);
79 if (ret == MAP_FAILED)
80 tst_brk(TBROK | TERRNO, "mremap");
81
82 for (j = 0; j < remap_size; j++) {
83 if (ret[j] != 0xff)
84 tst_brk(TBROK, "mremap bug");
85 }
86
87 exit(0);
88 }
89
do_mremap(void)90 static void do_mremap(void)
91 {
92 int i;
93
94 for (i = 0; i < 4; i++) {
95 if (SAFE_FORK() == 0)
96 do_child(i);
97 tst_reap_children();
98 }
99 tst_res(TPASS, "Still alive.");
100 }
101
setup(void)102 static void setup(void)
103 {
104 long memfree;
105
106 if (access(PATH_THP, F_OK) == -1)
107 tst_brk(TCONF, "THP not enabled in kernel?");
108
109 check_hugepage();
110
111 ps = sysconf(_SC_PAGESIZE);
112 hps = SAFE_READ_MEMINFO("Hugepagesize:") * 1024;
113 size = hps * 4;
114
115 memfree = (SAFE_READ_MEMINFO("MemFree:") * 1024 +
116 SAFE_READ_MEMINFO("Cached:") * 1024);
117 if (memfree < size * 2)
118 tst_brk(TCONF, "not enough memory");
119 }
120
121 static struct tst_test test = {
122 .setup = setup,
123 .test_all = do_mremap,
124 .forks_child = 1,
125 };
126
127 #else
128 TST_TEST_TCONF("MREMAP_FIXED not present in <sys/mman.h>");
129 #endif /* HAVE_MREMAP_FIXED */
130