1 /*
2 * Copyright (c) 2016 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 3 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 the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program. If not, see <http://www.gnu.org/licenses/>.
16 */
17
18 /*
19 * DESCRIPTION
20 *
21 * Page fault occurs in spite that madvise(WILLNEED) system call is called
22 * to prefetch the page. This issue is reproduced by running a program
23 * which sequentially accesses to a shared memory and calls madvise(WILLNEED)
24 * to the next page on a page fault.
25 *
26 * This bug is present in all RHEL7 versions. It looks like this was fixed in
27 * mainline kernel > v3.15 by the following patch:
28 *
29 * commit 55231e5c898c5c03c14194001e349f40f59bd300
30 * Author: Johannes Weiner <hannes@cmpxchg.org>
31 * Date: Thu May 22 11:54:17 2014 -0700
32 *
33 * mm: madvise: fix MADV_WILLNEED on shmem swapouts
34 */
35
36 #include <errno.h>
37 #include <sys/sysinfo.h>
38 #include "tst_test.h"
39
40 #define GB_SZ (1024*1024*1024)
41
42 static long dst_max;
43 static int pg_sz;
44
setup(void)45 static void setup(void)
46 {
47 struct sysinfo sys_buf;
48
49 sysinfo(&sys_buf);
50
51 if (sys_buf.totalram < 2L * GB_SZ)
52 tst_brk(TCONF, "Test requires more than 2GB of RAM");
53 if (sys_buf.totalram > 100L * GB_SZ)
54 tst_brk(TCONF, "System RAM is too large, skip test");
55
56 dst_max = sys_buf.totalram / GB_SZ;
57 tst_res(TINFO, "dst_max = %ld", dst_max);
58
59 pg_sz = getpagesize();
60 }
61
get_page_fault_num(void)62 static int get_page_fault_num(void)
63 {
64 int pg;
65
66 SAFE_FILE_SCANF("/proc/self/stat",
67 "%*s %*s %*s %*s %*s %*s %*s %*s %*s %*s %*s %d",
68 &pg);
69
70 return pg;
71 }
72
test_advice_willneed(void)73 static void test_advice_willneed(void)
74 {
75 int i;
76 char *src;
77 char *dst[100];
78 int page_fault_num_1;
79 int page_fault_num_2;
80
81 /* allocate source memory (1GB only) */
82 src = SAFE_MMAP(NULL, 1 * GB_SZ, PROT_READ | PROT_WRITE,
83 MAP_SHARED | MAP_ANONYMOUS,
84 -1, 0);
85
86 /* allocate destination memory (array) */
87 for (i = 0; i < dst_max; ++i)
88 dst[i] = SAFE_MMAP(NULL, 1 * GB_SZ,
89 PROT_READ | PROT_WRITE,
90 MAP_SHARED | MAP_ANONYMOUS,
91 -1, 0);
92
93 /* memmove source to each destination memories (for SWAP-OUT) */
94 for (i = 0; i < dst_max; ++i)
95 memmove(dst[i], src, 1 * GB_SZ);
96
97 tst_res(TINFO, "PageFault(no madvice): %d", get_page_fault_num());
98
99 /* Do madvice() to dst[0] */
100 TEST(madvise(dst[0], pg_sz, MADV_WILLNEED));
101 if (TEST_RETURN == -1)
102 tst_brk(TBROK | TERRNO, "madvise failed");
103
104 page_fault_num_1 = get_page_fault_num();
105 tst_res(TINFO, "PageFault(madvice / no mem access): %d",
106 page_fault_num_1);
107
108 *dst[0] = 'a';
109 page_fault_num_2 = get_page_fault_num();
110 tst_res(TINFO, "PageFault(madvice / mem access): %d",
111 page_fault_num_2);
112
113 if (page_fault_num_1 != page_fault_num_2)
114 tst_res(TFAIL, "Bug has been reproduced");
115 else
116 tst_res(TPASS, "Regression test pass");
117
118 SAFE_MUNMAP(src, 1 * GB_SZ);
119 for (i = 0; i < dst_max; ++i)
120 SAFE_MUNMAP(dst[i], 1 * GB_SZ);
121 }
122
123 static struct tst_test test = {
124 .tid = "madvice06",
125 .test_all = test_advice_willneed,
126 .setup = setup,
127 };
128