hugetlb-soft-offline.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Test soft offline behavior for HugeTLB pages:
  4 * - if enable_soft_offline = 0, hugepages should stay intact and soft
  5 *   offlining failed with EOPNOTSUPP.
  6 * - if enable_soft_offline = 1, a hugepage should be dissolved and
  7 *   nr_hugepages/free_hugepages should be reduced by 1.
  8 *
  9 * Before running, make sure more than 2 hugepages of default_hugepagesz
 10 * are allocated. For example, if /proc/meminfo/Hugepagesize is 2048kB:
 11 *   echo 8 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
 12 */
 13
 14#define _GNU_SOURCE
 15#include <errno.h>
 16#include <stdlib.h>
 17#include <stdio.h>
 18#include <string.h>
 19#include <unistd.h>
 20
 21#include <linux/magic.h>
 22#include <linux/memfd.h>
 23#include <sys/mman.h>
 24#include <sys/statfs.h>
 25#include <sys/types.h>
 26
 27#include "kselftest.h"
 28
 29#ifndef MADV_SOFT_OFFLINE
 30#define MADV_SOFT_OFFLINE 101
 31#endif
 32
 33#define EPREFIX " !!! "
 34
 35static int do_soft_offline(int fd, size_t len, int expect_errno)
 36{
 37	char *filemap = NULL;
 38	char *hwp_addr = NULL;
 39	const unsigned long pagesize = getpagesize();
 40	int ret = 0;
 41
 42	if (ftruncate(fd, len) < 0) {
 43		ksft_perror(EPREFIX "ftruncate to len failed");
 44		return -1;
 45	}
 46
 47	filemap = mmap(NULL, len, PROT_READ | PROT_WRITE,
 48		       MAP_SHARED | MAP_POPULATE, fd, 0);
 49	if (filemap == MAP_FAILED) {
 50		ksft_perror(EPREFIX "mmap failed");
 51		ret = -1;
 52		goto untruncate;
 53	}
 54
 55	memset(filemap, 0xab, len);
 56	ksft_print_msg("Allocated %#lx bytes of hugetlb pages\n", len);
 57
 58	hwp_addr = filemap + len / 2;
 59	ret = madvise(hwp_addr, pagesize, MADV_SOFT_OFFLINE);
 60	ksft_print_msg("MADV_SOFT_OFFLINE %p ret=%d, errno=%d\n",
 61		       hwp_addr, ret, errno);
 62	if (ret != 0)
 63		ksft_perror(EPREFIX "madvise failed");
 64
 65	if (errno == expect_errno)
 66		ret = 0;
 67	else {
 68		ksft_print_msg("MADV_SOFT_OFFLINE should ret %d\n",
 69			       expect_errno);
 70		ret = -1;
 71	}
 72
 73	munmap(filemap, len);
 74untruncate:
 75	if (ftruncate(fd, 0) < 0)
 76		ksft_perror(EPREFIX "ftruncate back to 0 failed");
 77
 78	return ret;
 79}
 80
 81static int set_enable_soft_offline(int value)
 82{
 83	char cmd[256] = {0};
 84	FILE *cmdfile = NULL;
 85
 86	if (value != 0 && value != 1)
 87		return -EINVAL;
 88
 89	sprintf(cmd, "echo %d > /proc/sys/vm/enable_soft_offline", value);
 90	cmdfile = popen(cmd, "r");
 91
 92	if (cmdfile)
 93		ksft_print_msg("enable_soft_offline => %d\n", value);
 94	else {
 95		ksft_perror(EPREFIX "failed to set enable_soft_offline");
 96		return errno;
 97	}
 98
 99	pclose(cmdfile);
100	return 0;
101}
102
103static int read_nr_hugepages(unsigned long hugepage_size,
104			     unsigned long *nr_hugepages)
105{
106	char buffer[256] = {0};
107	char cmd[256] = {0};
108
109	sprintf(cmd, "cat /sys/kernel/mm/hugepages/hugepages-%ldkB/nr_hugepages",
110		hugepage_size);
111	FILE *cmdfile = popen(cmd, "r");
112
113	if (cmdfile == NULL) {
114		ksft_perror(EPREFIX "failed to popen nr_hugepages");
115		return -1;
116	}
117
118	if (!fgets(buffer, sizeof(buffer), cmdfile)) {
119		ksft_perror(EPREFIX "failed to read nr_hugepages");
120		pclose(cmdfile);
121		return -1;
122	}
123
124	*nr_hugepages = atoll(buffer);
125	pclose(cmdfile);
126	return 0;
127}
128
129static int create_hugetlbfs_file(struct statfs *file_stat)
130{
131	int fd;
132
133	fd = memfd_create("hugetlb_tmp", MFD_HUGETLB);
134	if (fd < 0) {
135		ksft_perror(EPREFIX "could not open hugetlbfs file");
136		return -1;
137	}
138
139	memset(file_stat, 0, sizeof(*file_stat));
140	if (fstatfs(fd, file_stat)) {
141		ksft_perror(EPREFIX "fstatfs failed");
142		goto close;
143	}
144	if (file_stat->f_type != HUGETLBFS_MAGIC) {
145		ksft_print_msg(EPREFIX "not hugetlbfs file\n");
146		goto close;
147	}
148
149	return fd;
150close:
151	close(fd);
152	return -1;
153}
154
155static void test_soft_offline_common(int enable_soft_offline)
156{
157	int fd;
158	int expect_errno = enable_soft_offline ? 0 : EOPNOTSUPP;
159	struct statfs file_stat;
160	unsigned long hugepagesize_kb = 0;
161	unsigned long nr_hugepages_before = 0;
162	unsigned long nr_hugepages_after = 0;
163	int ret;
164
165	ksft_print_msg("Test soft-offline when enabled_soft_offline=%d\n",
166		       enable_soft_offline);
167
168	fd = create_hugetlbfs_file(&file_stat);
169	if (fd < 0)
170		ksft_exit_fail_msg("Failed to create hugetlbfs file\n");
171
172	hugepagesize_kb = file_stat.f_bsize / 1024;
173	ksft_print_msg("Hugepagesize is %ldkB\n", hugepagesize_kb);
174
175	if (set_enable_soft_offline(enable_soft_offline) != 0) {
176		close(fd);
177		ksft_exit_fail_msg("Failed to set enable_soft_offline\n");
178	}
179
180	if (read_nr_hugepages(hugepagesize_kb, &nr_hugepages_before) != 0) {
181		close(fd);
182		ksft_exit_fail_msg("Failed to read nr_hugepages\n");
183	}
184
185	ksft_print_msg("Before MADV_SOFT_OFFLINE nr_hugepages=%ld\n",
186		       nr_hugepages_before);
187
188	ret = do_soft_offline(fd, 2 * file_stat.f_bsize, expect_errno);
189
190	if (read_nr_hugepages(hugepagesize_kb, &nr_hugepages_after) != 0) {
191		close(fd);
192		ksft_exit_fail_msg("Failed to read nr_hugepages\n");
193	}
194
195	ksft_print_msg("After MADV_SOFT_OFFLINE nr_hugepages=%ld\n",
196		nr_hugepages_after);
197
198	// No need for the hugetlbfs file from now on.
199	close(fd);
200
201	if (enable_soft_offline) {
202		if (nr_hugepages_before != nr_hugepages_after + 1) {
203			ksft_test_result_fail("MADV_SOFT_OFFLINE should reduced 1 hugepage\n");
204			return;
205		}
206	} else {
207		if (nr_hugepages_before != nr_hugepages_after) {
208			ksft_test_result_fail("MADV_SOFT_OFFLINE reduced %lu hugepages\n",
209				nr_hugepages_before - nr_hugepages_after);
210			return;
211		}
212	}
213
214	ksft_test_result(ret == 0,
215			 "Test soft-offline when enabled_soft_offline=%d\n",
216			 enable_soft_offline);
217}
218
219int main(int argc, char **argv)
220{
221	ksft_print_header();
222	ksft_set_plan(2);
223
224	test_soft_offline_common(1);
225	test_soft_offline_common(0);
226
227	ksft_finished();
228}