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 static void *p, *p2, *p3, *p4;
51
do_mremap(void)52 static void do_mremap(void)
53 {
54 int i;
55 void *old_addr, *new_addr;
56
57 for (i = 0; i < 4; i++) {
58 p = SAFE_MEMALIGN(hps, size);
59 p2 = SAFE_MEMALIGN(hps, size);
60 p3 = SAFE_MEMALIGN(hps, size);
61
62 memset(p, 0xff, size);
63 memset(p2, 0xff, size);
64 memset(p3, 0x77, size);
65
66 /*
67 * Will try to do the following 4 mremaps cases:
68 * mremap(p, size-ps, size-ps, flag, p3);
69 * mremap(p, size-ps, size-ps, flag, p3+ps);
70 * mremap(p+ps, size-ps, size-ps, flag, p3);
71 * mremap(p+ps, size-ps, size-ps, flag, p3+ps);
72 */
73 old_addr = p + ps * (i >> 1);
74 new_addr = p3 + ps * (i & 1);
75 tst_res(TINFO, "mremap %p to %p", old_addr, new_addr);
76
77 p4 = mremap(old_addr, size - ps, size - ps,
78 MREMAP_FIXED | MREMAP_MAYMOVE, new_addr);
79 if (p4 == MAP_FAILED)
80 tst_brk(TBROK | TERRNO, "mremap");
81 if (memcmp(p4, p2, size - ps))
82 tst_brk(TBROK, "mremap bug");
83 }
84
85 tst_res(TPASS, "Still alive.");
86 }
87
setup(void)88 static void setup(void)
89 {
90 if (access(PATH_THP, F_OK) == -1)
91 tst_brk(TCONF, "THP not enabled in kernel?");
92
93 check_hugepage();
94
95 ps = sysconf(_SC_PAGESIZE);
96 hps = SAFE_READ_MEMINFO("Hugepagesize:") * 1024;
97 size = hps * 4;
98 }
99
100 static struct tst_test test = {
101 .needs_root = 1,
102 .setup = setup,
103 .test_all = do_mremap,
104 };
105
106 #else
107 TST_TEST_TCONF("MREMAP_FIXED not present in <sys/mman.h>");
108 #endif /* HAVE_MREMAP_FIXED */
109