summaryrefslogtreecommitdiffstats
path: root/tools/testing/selftests/mm/uffd-stress.c
blob: 7e83829bbb335b98022c354a6871e8f6340e7328 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Stress userfaultfd syscall.
 *
 *  Copyright (C) 2015  Red Hat, Inc.
 *
 * This test allocates two virtual areas and bounces the physical
 * memory across the two virtual areas (from area_src to area_dst)
 * using userfaultfd.
 *
 * There are three threads running per CPU:
 *
 * 1) one per-CPU thread takes a per-page pthread_mutex in a random
 *    page of the area_dst (while the physical page may still be in
 *    area_src), and increments a per-page counter in the same page,
 *    and checks its value against a verification region.
 *
 * 2) another per-CPU thread handles the userfaults generated by
 *    thread 1 above. userfaultfd blocking reads or poll() modes are
 *    exercised interleaved.
 *
 * 3) one last per-CPU thread transfers the memory in the background
 *    at maximum bandwidth (if not already transferred by thread
 *    2). Each cpu thread takes cares of transferring a portion of the
 *    area.
 *
 * When all threads of type 3 completed the transfer, one bounce is
 * complete. area_src and area_dst are then swapped. All threads are
 * respawned and so the bounce is immediately restarted in the
 * opposite direction.
 *
 * per-CPU threads 1 by triggering userfaults inside
 * pthread_mutex_lock will also verify the atomicity of the memory
 * transfer (UFFDIO_COPY).
 */

#include "uffd-common.h"

#ifdef __NR_userfaultfd

#define BOUNCE_RANDOM		(1<<0)
#define BOUNCE_RACINGFAULTS	(1<<1)
#define BOUNCE_VERIFY		(1<<2)
#define BOUNCE_POLL		(1<<3)
static int bounces;

/* exercise the test_uffdio_*_eexist every ALARM_INTERVAL_SECS */
#define ALARM_INTERVAL_SECS 10
static char *zeropage;
pthread_attr_t attr;

#define swap(a, b) \
	do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)

const char *examples =
	"# Run anonymous memory test on 100MiB region with 99999 bounces:\n"
	"./uffd-stress anon 100 99999\n\n"
	"# Run share memory test on 1GiB region with 99 bounces:\n"
	"./uffd-stress shmem 1000 99\n\n"
	"# Run hugetlb memory test on 256MiB region with 50 bounces:\n"
	"./uffd-stress hugetlb 256 50\n\n"
	"# Run the same hugetlb test but using private file:\n"
	"./uffd-stress hugetlb-private 256 50\n\n"
	"# 10MiB-~6GiB 999 bounces anonymous test, "
	"continue forever unless an error triggers\n"
	"while ./uffd-stress anon $[RANDOM % 6000 + 10] 999; do true; done\n\n";

static void usage(void)
{
	fprintf(stderr, "\nUsage: ./uffd-stress <test type> <MiB> <bounces>\n\n");
	fprintf(stderr, "Supported <test type>: anon, hugetlb, "
		"hugetlb-private, shmem, shmem-private\n\n");
	fprintf(stderr, "Examples:\n\n");
	fprintf(stderr, "%s", examples);
	exit(1);
}

static void uffd_stats_reset(struct uffd_args *args, unsigned long n_cpus)
{
	int i;

	for (i = 0; i < n_cpus; i++) {
		args[i].cpu = i;
		args[i].apply_wp = test_uffdio_wp;
		args[i].missing_faults = 0;
		args[i].wp_faults = 0;
		args[i].minor_faults = 0;
	}
}

static void *locking_thread(void *arg)
{
	unsigned long cpu = (unsigned long) arg;
	unsigned long page_nr;
	unsigned long long count;

	if (!(bounces & BOUNCE_RANDOM)) {
		page_nr = -bounces;
		if (!(bounces & BOUNCE_RACINGFAULTS))
			page_nr += cpu * nr_pages_per_cpu;
	}

	while (!finished) {
		if (bounces & BOUNCE_RANDOM) {
			if (getrandom(&page_nr, sizeof(page_nr), 0) != sizeof(page_nr))
				err("getrandom failed");
		} else
			page_nr += 1;
		page_nr %= nr_pages;
		pthread_mutex_lock(area_mutex(area_dst, page_nr));
		count = *area_count(area_dst, page_nr);
		if (count != count_verify[page_nr])
			err("page_nr %lu memory corruption %llu %llu",
			    page_nr, count, count_verify[page_nr]);
		count++;
		*area_count(area_dst, page_nr) = count_verify[page_nr] = count;
		pthread_mutex_unlock(area_mutex(area_dst, page_nr));
	}

	return NULL;
}

static int copy_page_retry(int ufd, unsigned long offset)
{
	return __copy_page(ufd, offset, true, test_uffdio_wp);
}

pthread_mutex_t uffd_read_mutex = PTHREAD_MUTEX_INITIALIZER;

static void *uffd_read_thread(void *arg)
{
	struct uffd_args *args = (struct uffd_args *)arg;
	struct uffd_msg msg;

	pthread_mutex_unlock(&uffd_read_mutex);
	/* from here cancellation is ok */

	for (;;) {
		if (uffd_read_msg(uffd, &msg))
			continue;
		uffd_handle_page_fault(&msg, args);
	}

	return NULL;
}

static void *background_thread(void *arg)
{
	unsigned long cpu = (unsigned long) arg;
	unsigned long page_nr, start_nr, mid_nr, end_nr;

	start_nr = cpu * nr_pages_per_cpu;
	end_nr = (cpu+1) * nr_pages_per_cpu;
	mid_nr = (start_nr + end_nr) / 2;

	/* Copy the first half of the pages */
	for (page_nr = start_nr; page_nr < mid_nr; page_nr++)
		copy_page_retry(uffd, page_nr * page_size);

	/*
	 * If we need to test uffd-wp, set it up now.  Then we'll have
	 * at least the first half of the pages mapped already which
	 * can be write-protected for testing
	 */
	if (test_uffdio_wp)
		wp_range(uffd, (unsigned long)area_dst + start_nr * page_size,
			nr_pages_per_cpu * page_size, true);

	/*
	 * Continue the 2nd half of the page copying, handling write
	 * protection faults if any
	 */
	for (page_nr = mid_nr; page_nr < end_nr; page_nr++)
		copy_page_retry(uffd, page_nr * page_size);

	return NULL;
}

static int stress(struct uffd_args *args)
{
	unsigned long cpu;
	pthread_t locking_threads[nr_cpus];
	pthread_t uffd_threads[nr_cpus];
	pthread_t background_threads[nr_cpus];

	finished = 0;
	for (cpu = 0; cpu < nr_cpus; cpu++) {
		if (pthread_create(&locking_threads[cpu], &attr,
				   locking_thread, (void *)cpu))
			return 1;
		if (bounces & BOUNCE_POLL) {
			if (pthread_create(&uffd_threads[cpu], &attr, uffd_poll_thread, &args[cpu]))
				err("uffd_poll_thread create");
		} else {
			if (pthread_create(&uffd_threads[cpu], &attr,
					   uffd_read_thread,
					   (void *)&args[cpu]))
				return 1;
			pthread_mutex_lock(&uffd_read_mutex);
		}
		if (pthread_create(&background_threads[cpu], &attr,
				   background_thread, (void *)cpu))
			return 1;
	}
	for (cpu = 0; cpu < nr_cpus; cpu++)
		if (pthread_join(background_threads[cpu], NULL))
			return 1;

	/*
	 * Be strict and immediately zap area_src, the whole area has
	 * been transferred already by the background treads. The
	 * area_src could then be faulted in a racy way by still
	 * running uffdio_threads reading zeropages after we zapped
	 * area_src (but they're guaranteed to get -EEXIST from
	 * UFFDIO_COPY without writing zero pages into area_dst
	 * because the background threads already completed).
	 */
	uffd_test_ops->release_pages(area_src);

	finished = 1;
	for (cpu = 0; cpu < nr_cpus; cpu++)
		if (pthread_join(locking_threads[cpu], NULL))
			return 1;

	for (cpu = 0; cpu < nr_cpus; cpu++) {
		char c;
		if (bounces & BOUNCE_POLL) {
			if (write(pipefd[cpu*2+1], &c, 1) != 1)
				err("pipefd write error");
			if (pthread_join(uffd_threads[cpu],
					 (void *)&args[cpu]))
				return 1;
		} else {
			if (pthread_cancel(uffd_threads[cpu]))
				return 1;
			if (pthread_join(uffd_threads[cpu], NULL))
				return 1;
		}
	}

	return 0;
}

static int userfaultfd_stress(void)
{
	void *area;
	unsigned long nr;
	struct uffd_args args[nr_cpus];
	uint64_t mem_size = nr_pages * page_size;

	memset(args, 0, sizeof(struct uffd_args) * nr_cpus);

	if (uffd_test_ctx_init(UFFD_FEATURE_WP_UNPOPULATED, NULL))
		err("context init failed");

	if (posix_memalign(&area, page_size, page_size))
		err("out of memory");
	zeropage = area;
	bzero(zeropage, page_size);

	pthread_mutex_lock(&uffd_read_mutex);

	pthread_attr_init(&attr);
	pthread_attr_setstacksize(&attr, 16*1024*1024);

	while (bounces--) {
		printf("bounces: %d, mode:", bounces);
		if (bounces & BOUNCE_RANDOM)
			printf(" rnd");
		if (bounces & BOUNCE_RACINGFAULTS)
			printf(" racing");
		if (bounces & BOUNCE_VERIFY)
			printf(" ver");
		if (bounces & BOUNCE_POLL)
			printf(" poll");
		else
			printf(" read");
		printf(", ");
		fflush(stdout);

		if (bounces & BOUNCE_POLL)
			fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
		else
			fcntl(uffd, F_SETFL, uffd_flags & ~O_NONBLOCK);

		/* register */
		if (uffd_register(uffd, area_dst, mem_size,
				  true, test_uffdio_wp, false))
			err("register failure");

		if (area_dst_alias) {
			if (uffd_register(uffd, area_dst_alias, mem_size,
					  true, test_uffdio_wp, false))
				err("register failure alias");
		}

		/*
		 * The madvise done previously isn't enough: some
		 * uffd_thread could have read userfaults (one of
		 * those already resolved by the background thread)
		 * and it may be in the process of calling
		 * UFFDIO_COPY. UFFDIO_COPY will read the zapped
		 * area_src and it would map a zero page in it (of
		 * course such a UFFDIO_COPY is perfectly safe as it'd
		 * return -EEXIST). The problem comes at the next
		 * bounce though: that racing UFFDIO_COPY would
		 * generate zeropages in the area_src, so invalidating
		 * the previous MADV_DONTNEED. Without this additional
		 * MADV_DONTNEED those zeropages leftovers in the
		 * area_src would lead to -EEXIST failure during the
		 * next bounce, effectively leaving a zeropage in the
		 * area_dst.
		 *
		 * Try to comment this out madvise to see the memory
		 * corruption being caught pretty quick.
		 *
		 * khugepaged is also inhibited to collapse THP after
		 * MADV_DONTNEED only after the UFFDIO_REGISTER, so it's
		 * required to MADV_DONTNEED here.
		 */
		uffd_test_ops->release_pages(area_dst);

		uffd_stats_reset(args, nr_cpus);

		/* bounce pass */
		if (stress(args)) {
			uffd_test_ctx_clear();
			return 1;
		}

		/* Clear all the write protections if there is any */
		if (test_uffdio_wp)
			wp_range(uffd, (unsigned long)area_dst,
				 nr_pages * page_size, false);

		/* unregister */
		if (uffd_unregister(uffd, area_dst, mem_size))
			err("unregister failure");
		if (area_dst_alias) {
			if (uffd_unregister(uffd, area_dst_alias, mem_size))
				err("unregister failure alias");
		}

		/* verification */
		if (bounces & BOUNCE_VERIFY)
			for (nr = 0; nr < nr_pages; nr++)
				if (*area_count(area_dst, nr) != count_verify[nr])
					err("error area_count %llu %llu %lu\n",
					    *area_count(area_src, nr),
					    count_verify[nr], nr);

		/* prepare next bounce */
		swap(area_src, area_dst);

		swap(area_src_alias, area_dst_alias);

		uffd_stats_report(args, nr_cpus);
	}
	uffd_test_ctx_clear();

	return 0;
}

static void set_test_type(const char *type)
{
	if (!strcmp(type, "anon")) {
		test_type = TEST_ANON;
		uffd_test_ops = &anon_uffd_test_ops;
	} else if (!strcmp(type, "hugetlb")) {
		test_type = TEST_HUGETLB;
		uffd_test_ops = &hugetlb_uffd_test_ops;
		map_shared = true;
	} else if (!strcmp(type, "hugetlb-private")) {
		test_type = TEST_HUGETLB;
		uffd_test_ops = &hugetlb_uffd_test_ops;
	} else if (!strcmp(type, "shmem")) {
		map_shared = true;
		test_type = TEST_SHMEM;
		uffd_test_ops = &shmem_uffd_test_ops;
	} else if (!strcmp(type, "shmem-private")) {
		test_type = TEST_SHMEM;
		uffd_test_ops = &shmem_uffd_test_ops;
	}
}

static void parse_test_type_arg(const char *raw_type)
{
	uint64_t features = UFFD_API_FEATURES;

	set_test_type(raw_type);

	if (!test_type)
		err("failed to parse test type argument: '%s'", raw_type);

	if (test_type == TEST_HUGETLB)
		page_size = default_huge_page_size();
	else
		page_size = sysconf(_SC_PAGE_SIZE);

	if (!page_size)
		err("Unable to determine page size");
	if ((unsigned long) area_count(NULL, 0) + sizeof(unsigned long long) * 2
	    > page_size)
		err("Impossible to run this test");

	/*
	 * Whether we can test certain features depends not just on test type,
	 * but also on whether or not this particular kernel supports the
	 * feature.
	 */

	if (userfaultfd_open(&features))
		err("Userfaultfd open failed");

	test_uffdio_wp = test_uffdio_wp &&
		(features & UFFD_FEATURE_PAGEFAULT_FLAG_WP);

	close(uffd);
	uffd = -1;
}

static void sigalrm(int sig)
{
	if (sig != SIGALRM)
		abort();
	test_uffdio_copy_eexist = true;
	alarm(ALARM_INTERVAL_SECS);
}

int main(int argc, char **argv)
{
	size_t bytes;

	if (argc < 4)
		usage();

	if (signal(SIGALRM, sigalrm) == SIG_ERR)
		err("failed to arm SIGALRM");
	alarm(ALARM_INTERVAL_SECS);

	parse_test_type_arg(argv[1]);
	bytes = atol(argv[2]) * 1024 * 1024;

	nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);

	nr_pages_per_cpu = bytes / page_size / nr_cpus;
	if (!nr_pages_per_cpu) {
		_err("invalid MiB");
		usage();
	}

	bounces = atoi(argv[3]);
	if (bounces <= 0) {
		_err("invalid bounces");
		usage();
	}
	nr_pages = nr_pages_per_cpu * nr_cpus;

	printf("nr_pages: %lu, nr_pages_per_cpu: %lu\n",
	       nr_pages, nr_pages_per_cpu);
	return userfaultfd_stress();
}

#else /* __NR_userfaultfd */

#warning "missing __NR_userfaultfd definition"

int main(void)
{
	printf("skip: Skipping userfaultfd test (missing __NR_userfaultfd)\n");
	return KSFT_SKIP;
}

#endif /* __NR_userfaultfd */