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1 /*
2  * Copyright (C) 2010-2017  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  * Kernel Samepage Merging (KSM)
15  *
16  * Basic tests were to start several programs with same and different
17  * memory contents and ensure only to merge the ones with the same
18  * contents. When changed the content of one of merged pages in a
19  * process and to the mode "unmerging", it should discard all merged
20  * pages there. Also tested it is possible to disable KSM. There are
21  * also command-line options to specify the memory allocation size, and
22  * number of processes have same memory contents so it is possible to
23  * test more advanced things like KSM + OOM etc.
24  *
25  * Prerequisites:
26  *
27  * 1) ksm and ksmtuned daemons need to be disabled. Otherwise, it could
28  *    distrub the testing as they also change some ksm tunables depends
29  *    on current workloads.
30  *
31  * The test steps are:
32  * - Check ksm feature and backup current run setting.
33  * - Change run setting to 1 - merging.
34  * - 3 memory allocation programs have the memory contents that 2 of
35  *   them are all 'a' and one is all 'b'.
36  * - Check ksm statistics and verify the content.
37  * - 1 program changes the memory content from all 'a' to all 'b'.
38  * - Check ksm statistics and verify the content.
39  * - All programs change the memory content to all 'd'.
40  * - Check ksm statistics and verify the content.
41  * - Change one page of a process.
42  * - Check ksm statistics and verify the content.
43  * - Change run setting to 2 - unmerging.
44  * - Check ksm statistics and verify the content.
45  * - Change run setting to 0 - stop.
46  */
47 
48 #include <sys/types.h>
49 #include <sys/mman.h>
50 #include <sys/stat.h>
51 #include <sys/wait.h>
52 #include <errno.h>
53 #include <fcntl.h>
54 #include <signal.h>
55 #include <stdio.h>
56 #include <stdlib.h>
57 #include <string.h>
58 #include <unistd.h>
59 #include "mem.h"
60 #include "ksm_common.h"
61 
verify_ksm(void)62 static void verify_ksm(void)
63 {
64 	create_same_memory(size, num, unit);
65 }
66 
setup(void)67 static void setup(void)
68 {
69 	if (access(PATH_KSM, F_OK) == -1)
70 		tst_brk(TCONF, "KSM configuration is not enabled");
71 
72 	parse_ksm_options(opt_sizestr, &size, opt_numstr, &num, opt_unitstr, &unit);
73 
74 	/*
75 	 * kernel commit 90bd6fd introduced a new KSM sysfs knob
76 	 * /sys/kernel/mm/ksm/merge_across_nodes, setting it to '0'
77 	 * will prevent KSM pages being merged across numa nodes,
78 	 * which will cause the case fail, so we need to make sure
79 	 * it is enabled before testing.
80 	 */
81 	if (access(PATH_KSM "merge_across_nodes", F_OK) == 0) {
82 		SAFE_FILE_SCANF(PATH_KSM "merge_across_nodes",
83 				"%d", &merge_across_nodes);
84 		SAFE_FILE_PRINTF(PATH_KSM "merge_across_nodes", "1");
85 	}
86 }
87 
cleanup(void)88 static void cleanup(void)
89 {
90 	if (access(PATH_KSM "merge_across_nodes", F_OK) == 0)
91 		FILE_PRINTF(PATH_KSM "merge_across_nodes",
92 				 "%d", merge_across_nodes);
93 }
94 
95 static struct tst_test test = {
96 	.needs_root = 1,
97 	.forks_child = 1,
98 	.options = ksm_options,
99 	.setup = setup,
100 	.cleanup = cleanup,
101 	.save_restore = save_restore,
102 	.test_all = verify_ksm,
103 	.min_kver = "2.6.32",
104 };
105