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1// SPDX-License-Identifier: GPL-2.0
2/*
3 *
4 * A test for the patch "Allow compaction of unevictable pages".
5 * With this patch we should be able to allocate at least 1/4
6 * of RAM in huge pages. Without the patch much less is
7 * allocated.
8 */
9
10#include <stdio.h>
11#include <stdlib.h>
12#include <sys/mman.h>
13#include <sys/resource.h>
14#include <fcntl.h>
15#include <errno.h>
16#include <unistd.h>
17#include <string.h>
18
19#include "kselftest.h"
20#include "hugepage_settings.h"
21
22#define MAP_SIZE_MB 100
23#define MAP_SIZE (MAP_SIZE_MB * 1024 * 1024)
24
25struct map_list {
26 void *map;
27 struct map_list *next;
28};
29
30int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize)
31{
32 char buffer[256];
33 int found = 0;
34 FILE *file;
35 int ret = -1;
36
37 file = fopen("/proc/meminfo", "r");
38 if (!file) {
39 ksft_print_msg("Failed to open /proc/meminfo: %s\n",
40 strerror(errno));
41 return -1;
42 }
43
44 while (fgets(buffer, sizeof(buffer), file) && found != 2) {
45 if (sscanf(buffer, "MemFree: %lu kB", memfree) == 1 ||
46 sscanf(buffer, "Hugepagesize: %lu kB", hugepagesize) == 1)
47 found++;
48 }
49
50 if (ferror(file))
51 ksft_print_msg("Failed to read /proc/meminfo: %s\n",
52 strerror(errno));
53 else if (found != 2)
54 ksft_print_msg("Failed to parse /proc/meminfo\n");
55 else
56 ret = 0;
57
58 fclose(file);
59 return ret;
60}
61
62int prereq(void)
63{
64 char allowed;
65 int fd;
66
67 fd = open("/proc/sys/vm/compact_unevictable_allowed",
68 O_RDONLY | O_NONBLOCK);
69 if (fd < 0) {
70 ksft_print_msg("Failed to open /proc/sys/vm/compact_unevictable_allowed: %s\n",
71 strerror(errno));
72 return -1;
73 }
74
75 if (read(fd, &allowed, sizeof(char)) != sizeof(char)) {
76 ksft_print_msg("Failed to read from /proc/sys/vm/compact_unevictable_allowed: %s\n",
77 strerror(errno));
78 close(fd);
79 return -1;
80 }
81
82 close(fd);
83 if (allowed == '1')
84 return 0;
85
86 ksft_print_msg("Compaction isn't allowed\n");
87 return -1;
88}
89
90int check_compaction(unsigned long mem_free, unsigned long hugepage_size)
91{
92 unsigned long nr_hugepages;
93 int compaction_index = 0;
94 int ret = -1;
95
96 /* We want to test with 80% of available memory. Else, OOM killer comes
97 in to play */
98 mem_free = mem_free * 0.8;
99
100 /*
101 * Request huge pages for about half of the free memory. The Kernel
102 * will allocate as much as it can, and we expect it will get at least 1/3
103 */
104 nr_hugepages = mem_free / hugepage_size / 2;
105 hugetlb_set_nr_default_pages(nr_hugepages);
106
107 /* We should have been able to request at least 1/3 rd of the memory in
108 huge pages */
109 nr_hugepages = hugetlb_nr_default_pages();
110 if (!nr_hugepages) {
111 ksft_print_msg("ERROR: No memory is available as huge pages\n");
112 goto out;
113 }
114 compaction_index = mem_free/(nr_hugepages * hugepage_size);
115
116 ksft_print_msg("Number of huge pages allocated = %lu\n", nr_hugepages);
117
118 if (compaction_index > 3) {
119 ksft_print_msg("ERROR: Less than 1/%d of memory is available\n"
120 "as huge pages\n", compaction_index);
121 goto out;
122 }
123
124 ret = 0;
125
126 out:
127 ksft_test_result(ret == 0, "check_compaction\n");
128 return ret;
129}
130
131int main(int argc, char **argv)
132{
133 struct rlimit lim;
134 struct map_list *list = NULL, *entry;
135 size_t page_size, i;
136 void *map = NULL;
137 unsigned long mem_free = 0;
138 unsigned long hugepage_size = 0;
139 long mem_fragmentable_MB = 0;
140
141 ksft_print_header();
142
143 if (prereq() || geteuid())
144 ksft_exit_skip("Prerequisites unsatisfied\n");
145
146 /* Start the test without hugepages reducing mem_free */
147 if (!hugetlb_setup_default_exact(0))
148 ksft_exit_skip("Could not reset nr_hugepages\n");
149
150 ksft_set_plan(1);
151
152 lim.rlim_cur = RLIM_INFINITY;
153 lim.rlim_max = RLIM_INFINITY;
154 if (setrlimit(RLIMIT_MEMLOCK, &lim))
155 ksft_exit_fail_msg("Failed to set rlimit: %s\n", strerror(errno));
156
157 page_size = getpagesize();
158
159 if (read_memory_info(&mem_free, &hugepage_size) != 0)
160 ksft_exit_fail_msg("Failed to get meminfo\n");
161
162 mem_fragmentable_MB = mem_free * 0.8 / 1024;
163
164 while (mem_fragmentable_MB > 0) {
165 map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
166 MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0);
167 if (map == MAP_FAILED)
168 break;
169
170 entry = malloc(sizeof(struct map_list));
171 if (!entry) {
172 munmap(map, MAP_SIZE);
173 break;
174 }
175 entry->map = map;
176 entry->next = list;
177 list = entry;
178
179 /* Write something (in this case the address of the map) to
180 * ensure that KSM can't merge the mapped pages
181 */
182 for (i = 0; i < MAP_SIZE; i += page_size)
183 *(unsigned long *)(map + i) = (unsigned long)map + i;
184
185 mem_fragmentable_MB -= MAP_SIZE_MB;
186 }
187
188 /* Unmap every other entry in the list to create fragmentation with
189 * locked pages before invoking check_compaction().
190 */
191 for (entry = list; entry != NULL; entry = entry->next) {
192 munmap(entry->map, MAP_SIZE);
193 if (!entry->next)
194 break;
195 entry = entry->next;
196 }
197
198 if (check_compaction(mem_free, hugepage_size) == 0)
199 ksft_exit_pass();
200
201 ksft_exit_fail();
202}