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
 21#define MAP_SIZE_MB	100
 22#define MAP_SIZE	(MAP_SIZE_MB * 1024 * 1024)
 23
 24struct map_list {
 25	void *map;
 26	struct map_list *next;
 27};
 28
 29int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize)
 30{
 31	char  buffer[256] = {0};
 32	char *cmd = "cat /proc/meminfo | grep -i memfree | grep -o '[0-9]*'";
 33	FILE *cmdfile = popen(cmd, "r");
 34
 35	if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
 36		ksft_print_msg("Failed to read meminfo: %s\n", strerror(errno));
 37		return -1;
 38	}
 39
 40	pclose(cmdfile);
 41
 42	*memfree = atoll(buffer);
 43	cmd = "cat /proc/meminfo | grep -i hugepagesize | grep -o '[0-9]*'";
 44	cmdfile = popen(cmd, "r");
 45
 46	if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
 47		ksft_print_msg("Failed to read meminfo: %s\n", strerror(errno));
 48		return -1;
 49	}
 50
 51	pclose(cmdfile);
 52	*hugepagesize = atoll(buffer);
 53
 54	return 0;
 55}
 56
 57int prereq(void)
 58{
 59	char allowed;
 60	int fd;
 61
 62	fd = open("/proc/sys/vm/compact_unevictable_allowed",
 63		  O_RDONLY | O_NONBLOCK);
 64	if (fd < 0) {
 65		ksft_print_msg("Failed to open /proc/sys/vm/compact_unevictable_allowed: %s\n",
 66			       strerror(errno));
 67		return -1;
 68	}
 69
 70	if (read(fd, &allowed, sizeof(char)) != sizeof(char)) {
 71		ksft_print_msg("Failed to read from /proc/sys/vm/compact_unevictable_allowed: %s\n",
 72			       strerror(errno));
 73		close(fd);
 74		return -1;
 75	}
 76
 77	close(fd);
 78	if (allowed == '1')
 79		return 0;
 80
 81	ksft_print_msg("Compaction isn't allowed\n");
 82	return -1;
 83}
 84
 85int check_compaction(unsigned long mem_free, unsigned int hugepage_size)
 86{
 87	int fd, ret = -1;
 88	int compaction_index = 0;
 89	char initial_nr_hugepages[10] = {0};
 90	char nr_hugepages[10] = {0};
 91
 92	/* We want to test with 80% of available memory. Else, OOM killer comes
 93	   in to play */
 94	mem_free = mem_free * 0.8;
 95
 96	fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
 97	if (fd < 0) {
 98		ksft_print_msg("Failed to open /proc/sys/vm/nr_hugepages: %s\n",
 99			       strerror(errno));
100		ret = -1;
101		goto out;
102	}
103
104	if (read(fd, initial_nr_hugepages, sizeof(initial_nr_hugepages)) <= 0) {
105		ksft_print_msg("Failed to read from /proc/sys/vm/nr_hugepages: %s\n",
106			       strerror(errno));
107		goto close_fd;
108	}
109
110	/* Start with the initial condition of 0 huge pages*/
111	if (write(fd, "0", sizeof(char)) != sizeof(char)) {
112		ksft_print_msg("Failed to write 0 to /proc/sys/vm/nr_hugepages: %s\n",
113			       strerror(errno));
114		goto close_fd;
115	}
116
117	lseek(fd, 0, SEEK_SET);
118
119	/* Request a large number of huge pages. The Kernel will allocate
120	   as much as it can */
121	if (write(fd, "100000", (6*sizeof(char))) != (6*sizeof(char))) {
122		ksft_print_msg("Failed to write 100000 to /proc/sys/vm/nr_hugepages: %s\n",
123			       strerror(errno));
124		goto close_fd;
125	}
126
127	lseek(fd, 0, SEEK_SET);
128
129	if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
130		ksft_print_msg("Failed to re-read from /proc/sys/vm/nr_hugepages: %s\n",
131			       strerror(errno));
132		goto close_fd;
133	}
134
135	/* We should have been able to request at least 1/3 rd of the memory in
136	   huge pages */
137	compaction_index = mem_free/(atoi(nr_hugepages) * hugepage_size);
138
139	lseek(fd, 0, SEEK_SET);
140
141	if (write(fd, initial_nr_hugepages, strlen(initial_nr_hugepages))
142	    != strlen(initial_nr_hugepages)) {
143		ksft_print_msg("Failed to write value to /proc/sys/vm/nr_hugepages: %s\n",
144			       strerror(errno));
145		goto close_fd;
146	}
147
148	ksft_print_msg("Number of huge pages allocated = %d\n",
149		       atoi(nr_hugepages));
150
151	if (compaction_index > 3) {
152		ksft_print_msg("ERROR: Less that 1/%d of memory is available\n"
153			       "as huge pages\n", compaction_index);
154		goto close_fd;
155	}
156
157	ret = 0;
158
159 close_fd:
160	close(fd);
161 out:
162	ksft_test_result(ret == 0, "check_compaction\n");
163	return ret;
164}
165
166
167int main(int argc, char **argv)
168{
169	struct rlimit lim;
170	struct map_list *list = NULL, *entry;
171	size_t page_size, i;
172	void *map = NULL;
173	unsigned long mem_free = 0;
174	unsigned long hugepage_size = 0;
175	long mem_fragmentable_MB = 0;
176
177	ksft_print_header();
178
179	if (prereq() || geteuid())
180		return ksft_exit_skip("Prerequisites unsatisfied\n");
181
182	ksft_set_plan(1);
183
184	lim.rlim_cur = RLIM_INFINITY;
185	lim.rlim_max = RLIM_INFINITY;
186	if (setrlimit(RLIMIT_MEMLOCK, &lim))
187		ksft_exit_fail_msg("Failed to set rlimit: %s\n", strerror(errno));
188
189	page_size = getpagesize();
190
191	if (read_memory_info(&mem_free, &hugepage_size) != 0)
192		ksft_exit_fail_msg("Failed to get meminfo\n");
193
194	mem_fragmentable_MB = mem_free * 0.8 / 1024;
195
196	while (mem_fragmentable_MB > 0) {
197		map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
198			   MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0);
199		if (map == MAP_FAILED)
200			break;
201
202		entry = malloc(sizeof(struct map_list));
203		if (!entry) {
204			munmap(map, MAP_SIZE);
205			break;
206		}
207		entry->map = map;
208		entry->next = list;
209		list = entry;
210
211		/* Write something (in this case the address of the map) to
212		 * ensure that KSM can't merge the mapped pages
213		 */
214		for (i = 0; i < MAP_SIZE; i += page_size)
215			*(unsigned long *)(map + i) = (unsigned long)map + i;
216
217		mem_fragmentable_MB -= MAP_SIZE_MB;
218	}
219
220	for (entry = list; entry != NULL; entry = entry->next) {
221		munmap(entry->map, MAP_SIZE);
222		if (!entry->next)
223			break;
224		entry = entry->next;
225	}
226
227	if (check_compaction(mem_free, hugepage_size) == 0)
228		return ksft_exit_pass();
229
230	return ksft_exit_fail();
231}