1 /*
2 * Copyright (C) 2010 Red Hat, Inc.
3 * This program is free software; you can redistribute it and/or
4 * modify it under the terms of version 2 of the GNU General Public
5 * License as published by the Free Software Foundation.
6 *
7 * This program is distributed in the hope that it would be useful,
8 * but WITHOUT ANY WARRANTY; without even the implied warranty of
9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
10 *
11 * Further, this software is distributed without any warranty that it
12 * is free of the rightful claim of any third person regarding
13 * infringement or the like. Any license provided herein, whether
14 * implied or otherwise, applies only to this software file. Patent
15 * licenses, if any, provided herein do not apply to combinations of
16 * this program with other software, or any other product whatsoever.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
21 * 02110-1301, USA.
22 */
23
24 /*
25 * mmap/munmap /dev/zero: a common way of malloc()/free() anonymous
26 * memory on Solaris.
27 *
28 * The basic purpose of this is a to test if it is possible to map and
29 * unmap /dev/zero, and to read and write the mapping. Being inspired
30 * by two bugs in the past, the design of the test was added some
31 * variations based on the reproducers for them. It also accept an
32 * option to mmap/munmap anonymous pages.
33 *
34 * One is to trigger panic with transparent hugepage feature that
35 * split_huge_page is very strict in checking the rmap walk was
36 * perfect. Keep it strict because if page_mapcount isn't stable and
37 * just right, the __split_huge_page_refcount that follows the rmap
38 * walk could lead to erratic page_count()s for the subpages. The bug
39 * in fork lead to the rmap walk finding the parent huge-pmd twice
40 * instead of just one, because the anon_vma_chain objects of the
41 * child vma still point to the vma->vm_mm of the parent. That trips
42 * on the split_huge_page mapcount vs page_mapcount check leading to a
43 * BUG_ON.
44 *
45 * The other bug is mmap() of /dev/zero results in calling map_zero()
46 * which on RHEL5 maps the ZERO_PAGE in every PTE within that virtual
47 * address range. Since the application which maps a region from 5M to
48 * 16M in size is also multi-threaded the subsequent munmap() of
49 * /dev/zero results is TLB shootdowns to all other CPUs. When this
50 * happens thousands or millions of times the application performance
51 * is terrible. The mapping ZERO_PAGE in every pte within that virtual
52 * address range was an optimization to make the subsequent pagefault
53 * times faster on RHEL5 that has been removed/changed upstream.
54 */
55 #include <sys/types.h>
56 #include <sys/stat.h>
57 #include <sys/wait.h>
58 #include <sys/mman.h>
59 #include <errno.h>
60 #include <unistd.h>
61 #include <stdlib.h>
62 #include <stdio.h>
63 #include <fcntl.h>
64 #include "test.h"
65 #include "config.h"
66
67 #define SIZE (5*1024*1024)
68 #define PATH_KSM "/sys/kernel/mm/ksm/"
69
70 char *TCID = "mmap10";
71 int TST_TOTAL = 1;
72
73 static int fd, opt_anon, opt_ksm;
74 static long ps;
75 static char *x;
76
77 void setup(void);
78 void cleanup(void);
79 void mmapzero(void);
80 void help(void);
81
82 static option_t options[] = {
83 {"a", &opt_anon, NULL},
84 {"s", &opt_ksm, NULL},
85 {NULL, NULL, NULL}
86 };
87
main(int argc,char * argv[])88 int main(int argc, char *argv[])
89 {
90 int lc;
91
92 tst_parse_opts(argc, argv, options, help);
93
94 if (opt_ksm) {
95 if (access(PATH_KSM, F_OK) == -1)
96 tst_brkm(TCONF, NULL,
97 "KSM configuration is not enabled");
98 #ifdef HAVE_MADV_MERGEABLE
99 tst_resm(TINFO, "add to KSM regions.");
100 #else
101 tst_brkm(TCONF, NULL, "MADV_MERGEABLE missing in sys/mman.h");
102 #endif
103 }
104 if (opt_anon)
105 tst_resm(TINFO, "use anonymous pages.");
106 else
107 tst_resm(TINFO, "use /dev/zero.");
108
109 setup();
110
111 tst_resm(TINFO, "start tests.");
112 for (lc = 0; TEST_LOOPING(lc); lc++) {
113 tst_count = 0;
114 mmapzero();
115 }
116
117 cleanup();
118 tst_exit();
119 }
120
mmapzero(void)121 void mmapzero(void)
122 {
123 int n;
124
125 if (opt_anon) {
126 x = mmap(NULL, SIZE + SIZE - ps, PROT_READ | PROT_WRITE,
127 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
128 } else {
129 if ((fd = open("/dev/zero", O_RDWR, 0666)) < 0)
130 tst_brkm(TBROK | TERRNO, cleanup, "open");
131 x = mmap(NULL, SIZE + SIZE - ps, PROT_READ | PROT_WRITE,
132 MAP_PRIVATE, fd, 0);
133 }
134 if (x == MAP_FAILED)
135 tst_brkm(TFAIL | TERRNO, cleanup, "mmap");
136 #ifdef HAVE_MADV_MERGEABLE
137 if (opt_ksm) {
138 if (madvise(x, SIZE + SIZE - ps, MADV_MERGEABLE) == -1)
139 tst_brkm(TBROK | TERRNO, cleanup, "madvise");
140 }
141 #endif
142 x[SIZE] = 0;
143
144 switch (n = fork()) {
145 case -1:
146 tst_brkm(TBROK | TERRNO, cleanup, "fork");
147 case 0:
148 if (munmap(x + SIZE + ps, SIZE - ps - ps) == -1)
149 tst_brkm(TFAIL | TERRNO, cleanup, "munmap");
150 exit(0);
151 default:
152 break;
153 }
154
155 switch (n = fork()) {
156 case -1:
157 tst_brkm(TBROK | TERRNO, cleanup, "fork");
158 case 0:
159 if (munmap(x + SIZE + ps, SIZE - ps - ps) == -1)
160 tst_brkm(TFAIL | TERRNO, cleanup,
161 "subsequent munmap #1");
162 exit(0);
163 default:
164 switch (n = fork()) {
165 case -1:
166 tst_brkm(TBROK | TERRNO, cleanup, "fork");
167 case 0:
168 if (munmap(x + SIZE + ps, SIZE - ps - ps) == -1)
169 tst_brkm(TFAIL | TERRNO, cleanup,
170 "subsequent munmap #2");
171 exit(0);
172 default:
173 break;
174 }
175 break;
176 }
177
178 if (munmap(x, SIZE + SIZE - ps) == -1)
179 tst_resm(TFAIL | TERRNO, "munmap all");
180
181 while (waitpid(-1, &n, WUNTRACED | WCONTINUED) > 0)
182 if (WEXITSTATUS(n) != 0)
183 tst_resm(TFAIL, "child exit status is %d",
184 WEXITSTATUS(n));
185 }
186
cleanup(void)187 void cleanup(void)
188 {
189 }
190
setup(void)191 void setup(void)
192 {
193 tst_require_root();
194
195 tst_sig(FORK, DEF_HANDLER, cleanup);
196 TEST_PAUSE;
197
198 if ((ps = sysconf(_SC_PAGESIZE)) == -1)
199 tst_brkm(TBROK | TERRNO, cleanup, "sysconf(_SC_PAGESIZE)");
200 }
201
help(void)202 void help(void)
203 {
204 printf(" -a Test anonymous pages\n");
205 printf(" -s Add to KSM regions\n");
206 }
207