7b8171e3128a8715a62a10e020c69ea3ca1c5321
[muen/linux.git] / tools / testing / selftests / vm / userfaultfd.c
1 /*
2  * Stress userfaultfd syscall.
3  *
4  *  Copyright (C) 2015  Red Hat, Inc.
5  *
6  *  This work is licensed under the terms of the GNU GPL, version 2. See
7  *  the COPYING file in the top-level directory.
8  *
9  * This test allocates two virtual areas and bounces the physical
10  * memory across the two virtual areas (from area_src to area_dst)
11  * using userfaultfd.
12  *
13  * There are three threads running per CPU:
14  *
15  * 1) one per-CPU thread takes a per-page pthread_mutex in a random
16  *    page of the area_dst (while the physical page may still be in
17  *    area_src), and increments a per-page counter in the same page,
18  *    and checks its value against a verification region.
19  *
20  * 2) another per-CPU thread handles the userfaults generated by
21  *    thread 1 above. userfaultfd blocking reads or poll() modes are
22  *    exercised interleaved.
23  *
24  * 3) one last per-CPU thread transfers the memory in the background
25  *    at maximum bandwidth (if not already transferred by thread
26  *    2). Each cpu thread takes cares of transferring a portion of the
27  *    area.
28  *
29  * When all threads of type 3 completed the transfer, one bounce is
30  * complete. area_src and area_dst are then swapped. All threads are
31  * respawned and so the bounce is immediately restarted in the
32  * opposite direction.
33  *
34  * per-CPU threads 1 by triggering userfaults inside
35  * pthread_mutex_lock will also verify the atomicity of the memory
36  * transfer (UFFDIO_COPY).
37  *
38  * The program takes two parameters: the amounts of physical memory in
39  * megabytes (MiB) of the area and the number of bounces to execute.
40  *
41  * # 100MiB 99999 bounces
42  * ./userfaultfd 100 99999
43  *
44  * # 1GiB 99 bounces
45  * ./userfaultfd 1000 99
46  *
47  * # 10MiB-~6GiB 999 bounces, continue forever unless an error triggers
48  * while ./userfaultfd $[RANDOM % 6000 + 10] 999; do true; done
49  */
50
51 #define _GNU_SOURCE
52 #include <stdio.h>
53 #include <errno.h>
54 #include <unistd.h>
55 #include <stdlib.h>
56 #include <sys/types.h>
57 #include <sys/stat.h>
58 #include <fcntl.h>
59 #include <time.h>
60 #include <signal.h>
61 #include <poll.h>
62 #include <string.h>
63 #include <sys/mman.h>
64 #include <sys/syscall.h>
65 #include <sys/ioctl.h>
66 #include <sys/wait.h>
67 #include <pthread.h>
68 #include <linux/userfaultfd.h>
69 #include <setjmp.h>
70 #include <stdbool.h>
71
72 #include "../kselftest.h"
73
74 #ifdef __NR_userfaultfd
75
76 static unsigned long nr_cpus, nr_pages, nr_pages_per_cpu, page_size;
77
78 #define BOUNCE_RANDOM           (1<<0)
79 #define BOUNCE_RACINGFAULTS     (1<<1)
80 #define BOUNCE_VERIFY           (1<<2)
81 #define BOUNCE_POLL             (1<<3)
82 static int bounces;
83
84 #define TEST_ANON       1
85 #define TEST_HUGETLB    2
86 #define TEST_SHMEM      3
87 static int test_type;
88
89 /* exercise the test_uffdio_*_eexist every ALARM_INTERVAL_SECS */
90 #define ALARM_INTERVAL_SECS 10
91 static volatile bool test_uffdio_copy_eexist = true;
92 static volatile bool test_uffdio_zeropage_eexist = true;
93
94 static bool map_shared;
95 static int huge_fd;
96 static char *huge_fd_off0;
97 static unsigned long long *count_verify;
98 static int uffd, uffd_flags, finished, *pipefd;
99 static char *area_src, *area_src_alias, *area_dst, *area_dst_alias;
100 static char *zeropage;
101 pthread_attr_t attr;
102
103 /* pthread_mutex_t starts at page offset 0 */
104 #define area_mutex(___area, ___nr)                                      \
105         ((pthread_mutex_t *) ((___area) + (___nr)*page_size))
106 /*
107  * count is placed in the page after pthread_mutex_t naturally aligned
108  * to avoid non alignment faults on non-x86 archs.
109  */
110 #define area_count(___area, ___nr)                                      \
111         ((volatile unsigned long long *) ((unsigned long)               \
112                                  ((___area) + (___nr)*page_size +       \
113                                   sizeof(pthread_mutex_t) +             \
114                                   sizeof(unsigned long long) - 1) &     \
115                                  ~(unsigned long)(sizeof(unsigned long long) \
116                                                   -  1)))
117
118 static int anon_release_pages(char *rel_area)
119 {
120         int ret = 0;
121
122         if (madvise(rel_area, nr_pages * page_size, MADV_DONTNEED)) {
123                 perror("madvise");
124                 ret = 1;
125         }
126
127         return ret;
128 }
129
130 static void anon_allocate_area(void **alloc_area)
131 {
132         if (posix_memalign(alloc_area, page_size, nr_pages * page_size)) {
133                 fprintf(stderr, "out of memory\n");
134                 *alloc_area = NULL;
135         }
136 }
137
138 static void noop_alias_mapping(__u64 *start, size_t len, unsigned long offset)
139 {
140 }
141
142 /* HugeTLB memory */
143 static int hugetlb_release_pages(char *rel_area)
144 {
145         int ret = 0;
146
147         if (fallocate(huge_fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
148                                 rel_area == huge_fd_off0 ? 0 :
149                                 nr_pages * page_size,
150                                 nr_pages * page_size)) {
151                 perror("fallocate");
152                 ret = 1;
153         }
154
155         return ret;
156 }
157
158
159 static void hugetlb_allocate_area(void **alloc_area)
160 {
161         void *area_alias = NULL;
162         char **alloc_area_alias;
163         *alloc_area = mmap(NULL, nr_pages * page_size, PROT_READ | PROT_WRITE,
164                            (map_shared ? MAP_SHARED : MAP_PRIVATE) |
165                            MAP_HUGETLB,
166                            huge_fd, *alloc_area == area_src ? 0 :
167                            nr_pages * page_size);
168         if (*alloc_area == MAP_FAILED) {
169                 fprintf(stderr, "mmap of hugetlbfs file failed\n");
170                 *alloc_area = NULL;
171         }
172
173         if (map_shared) {
174                 area_alias = mmap(NULL, nr_pages * page_size, PROT_READ | PROT_WRITE,
175                                   MAP_SHARED | MAP_HUGETLB,
176                                   huge_fd, *alloc_area == area_src ? 0 :
177                                   nr_pages * page_size);
178                 if (area_alias == MAP_FAILED) {
179                         if (munmap(*alloc_area, nr_pages * page_size) < 0)
180                                 perror("hugetlb munmap"), exit(1);
181                         *alloc_area = NULL;
182                         return;
183                 }
184         }
185         if (*alloc_area == area_src) {
186                 huge_fd_off0 = *alloc_area;
187                 alloc_area_alias = &area_src_alias;
188         } else {
189                 alloc_area_alias = &area_dst_alias;
190         }
191         if (area_alias)
192                 *alloc_area_alias = area_alias;
193 }
194
195 static void hugetlb_alias_mapping(__u64 *start, size_t len, unsigned long offset)
196 {
197         if (!map_shared)
198                 return;
199         /*
200          * We can't zap just the pagetable with hugetlbfs because
201          * MADV_DONTEED won't work. So exercise -EEXIST on a alias
202          * mapping where the pagetables are not established initially,
203          * this way we'll exercise the -EEXEC at the fs level.
204          */
205         *start = (unsigned long) area_dst_alias + offset;
206 }
207
208 /* Shared memory */
209 static int shmem_release_pages(char *rel_area)
210 {
211         int ret = 0;
212
213         if (madvise(rel_area, nr_pages * page_size, MADV_REMOVE)) {
214                 perror("madvise");
215                 ret = 1;
216         }
217
218         return ret;
219 }
220
221 static void shmem_allocate_area(void **alloc_area)
222 {
223         *alloc_area = mmap(NULL, nr_pages * page_size, PROT_READ | PROT_WRITE,
224                            MAP_ANONYMOUS | MAP_SHARED, -1, 0);
225         if (*alloc_area == MAP_FAILED) {
226                 fprintf(stderr, "shared memory mmap failed\n");
227                 *alloc_area = NULL;
228         }
229 }
230
231 struct uffd_test_ops {
232         unsigned long expected_ioctls;
233         void (*allocate_area)(void **alloc_area);
234         int (*release_pages)(char *rel_area);
235         void (*alias_mapping)(__u64 *start, size_t len, unsigned long offset);
236 };
237
238 #define ANON_EXPECTED_IOCTLS            ((1 << _UFFDIO_WAKE) | \
239                                          (1 << _UFFDIO_COPY) | \
240                                          (1 << _UFFDIO_ZEROPAGE))
241
242 static struct uffd_test_ops anon_uffd_test_ops = {
243         .expected_ioctls = ANON_EXPECTED_IOCTLS,
244         .allocate_area  = anon_allocate_area,
245         .release_pages  = anon_release_pages,
246         .alias_mapping = noop_alias_mapping,
247 };
248
249 static struct uffd_test_ops shmem_uffd_test_ops = {
250         .expected_ioctls = ANON_EXPECTED_IOCTLS,
251         .allocate_area  = shmem_allocate_area,
252         .release_pages  = shmem_release_pages,
253         .alias_mapping = noop_alias_mapping,
254 };
255
256 static struct uffd_test_ops hugetlb_uffd_test_ops = {
257         .expected_ioctls = UFFD_API_RANGE_IOCTLS_BASIC,
258         .allocate_area  = hugetlb_allocate_area,
259         .release_pages  = hugetlb_release_pages,
260         .alias_mapping = hugetlb_alias_mapping,
261 };
262
263 static struct uffd_test_ops *uffd_test_ops;
264
265 static int my_bcmp(char *str1, char *str2, size_t n)
266 {
267         unsigned long i;
268         for (i = 0; i < n; i++)
269                 if (str1[i] != str2[i])
270                         return 1;
271         return 0;
272 }
273
274 static void *locking_thread(void *arg)
275 {
276         unsigned long cpu = (unsigned long) arg;
277         struct random_data rand;
278         unsigned long page_nr = *(&(page_nr)); /* uninitialized warning */
279         int32_t rand_nr;
280         unsigned long long count;
281         char randstate[64];
282         unsigned int seed;
283         time_t start;
284
285         if (bounces & BOUNCE_RANDOM) {
286                 seed = (unsigned int) time(NULL) - bounces;
287                 if (!(bounces & BOUNCE_RACINGFAULTS))
288                         seed += cpu;
289                 bzero(&rand, sizeof(rand));
290                 bzero(&randstate, sizeof(randstate));
291                 if (initstate_r(seed, randstate, sizeof(randstate), &rand))
292                         fprintf(stderr, "srandom_r error\n"), exit(1);
293         } else {
294                 page_nr = -bounces;
295                 if (!(bounces & BOUNCE_RACINGFAULTS))
296                         page_nr += cpu * nr_pages_per_cpu;
297         }
298
299         while (!finished) {
300                 if (bounces & BOUNCE_RANDOM) {
301                         if (random_r(&rand, &rand_nr))
302                                 fprintf(stderr, "random_r 1 error\n"), exit(1);
303                         page_nr = rand_nr;
304                         if (sizeof(page_nr) > sizeof(rand_nr)) {
305                                 if (random_r(&rand, &rand_nr))
306                                         fprintf(stderr, "random_r 2 error\n"), exit(1);
307                                 page_nr |= (((unsigned long) rand_nr) << 16) <<
308                                            16;
309                         }
310                 } else
311                         page_nr += 1;
312                 page_nr %= nr_pages;
313
314                 start = time(NULL);
315                 if (bounces & BOUNCE_VERIFY) {
316                         count = *area_count(area_dst, page_nr);
317                         if (!count)
318                                 fprintf(stderr,
319                                         "page_nr %lu wrong count %Lu %Lu\n",
320                                         page_nr, count,
321                                         count_verify[page_nr]), exit(1);
322
323
324                         /*
325                          * We can't use bcmp (or memcmp) because that
326                          * returns 0 erroneously if the memory is
327                          * changing under it (even if the end of the
328                          * page is never changing and always
329                          * different).
330                          */
331 #if 1
332                         if (!my_bcmp(area_dst + page_nr * page_size, zeropage,
333                                      page_size))
334                                 fprintf(stderr,
335                                         "my_bcmp page_nr %lu wrong count %Lu %Lu\n",
336                                         page_nr, count,
337                                         count_verify[page_nr]), exit(1);
338 #else
339                         unsigned long loops;
340
341                         loops = 0;
342                         /* uncomment the below line to test with mutex */
343                         /* pthread_mutex_lock(area_mutex(area_dst, page_nr)); */
344                         while (!bcmp(area_dst + page_nr * page_size, zeropage,
345                                      page_size)) {
346                                 loops += 1;
347                                 if (loops > 10)
348                                         break;
349                         }
350                         /* uncomment below line to test with mutex */
351                         /* pthread_mutex_unlock(area_mutex(area_dst, page_nr)); */
352                         if (loops) {
353                                 fprintf(stderr,
354                                         "page_nr %lu all zero thread %lu %p %lu\n",
355                                         page_nr, cpu, area_dst + page_nr * page_size,
356                                         loops);
357                                 if (loops > 10)
358                                         exit(1);
359                         }
360 #endif
361                 }
362
363                 pthread_mutex_lock(area_mutex(area_dst, page_nr));
364                 count = *area_count(area_dst, page_nr);
365                 if (count != count_verify[page_nr]) {
366                         fprintf(stderr,
367                                 "page_nr %lu memory corruption %Lu %Lu\n",
368                                 page_nr, count,
369                                 count_verify[page_nr]), exit(1);
370                 }
371                 count++;
372                 *area_count(area_dst, page_nr) = count_verify[page_nr] = count;
373                 pthread_mutex_unlock(area_mutex(area_dst, page_nr));
374
375                 if (time(NULL) - start > 1)
376                         fprintf(stderr,
377                                 "userfault too slow %ld "
378                                 "possible false positive with overcommit\n",
379                                 time(NULL) - start);
380         }
381
382         return NULL;
383 }
384
385 static void retry_copy_page(int ufd, struct uffdio_copy *uffdio_copy,
386                             unsigned long offset)
387 {
388         uffd_test_ops->alias_mapping(&uffdio_copy->dst,
389                                      uffdio_copy->len,
390                                      offset);
391         if (ioctl(ufd, UFFDIO_COPY, uffdio_copy)) {
392                 /* real retval in ufdio_copy.copy */
393                 if (uffdio_copy->copy != -EEXIST)
394                         fprintf(stderr, "UFFDIO_COPY retry error %Ld\n",
395                                 uffdio_copy->copy), exit(1);
396         } else {
397                 fprintf(stderr, "UFFDIO_COPY retry unexpected %Ld\n",
398                         uffdio_copy->copy), exit(1);
399         }
400 }
401
402 static int __copy_page(int ufd, unsigned long offset, bool retry)
403 {
404         struct uffdio_copy uffdio_copy;
405
406         if (offset >= nr_pages * page_size)
407                 fprintf(stderr, "unexpected offset %lu\n",
408                         offset), exit(1);
409         uffdio_copy.dst = (unsigned long) area_dst + offset;
410         uffdio_copy.src = (unsigned long) area_src + offset;
411         uffdio_copy.len = page_size;
412         uffdio_copy.mode = 0;
413         uffdio_copy.copy = 0;
414         if (ioctl(ufd, UFFDIO_COPY, &uffdio_copy)) {
415                 /* real retval in ufdio_copy.copy */
416                 if (uffdio_copy.copy != -EEXIST)
417                         fprintf(stderr, "UFFDIO_COPY error %Ld\n",
418                                 uffdio_copy.copy), exit(1);
419         } else if (uffdio_copy.copy != page_size) {
420                 fprintf(stderr, "UFFDIO_COPY unexpected copy %Ld\n",
421                         uffdio_copy.copy), exit(1);
422         } else {
423                 if (test_uffdio_copy_eexist && retry) {
424                         test_uffdio_copy_eexist = false;
425                         retry_copy_page(ufd, &uffdio_copy, offset);
426                 }
427                 return 1;
428         }
429         return 0;
430 }
431
432 static int copy_page_retry(int ufd, unsigned long offset)
433 {
434         return __copy_page(ufd, offset, true);
435 }
436
437 static int copy_page(int ufd, unsigned long offset)
438 {
439         return __copy_page(ufd, offset, false);
440 }
441
442 static void *uffd_poll_thread(void *arg)
443 {
444         unsigned long cpu = (unsigned long) arg;
445         struct pollfd pollfd[2];
446         struct uffd_msg msg;
447         struct uffdio_register uffd_reg;
448         int ret;
449         unsigned long offset;
450         char tmp_chr;
451         unsigned long userfaults = 0;
452
453         pollfd[0].fd = uffd;
454         pollfd[0].events = POLLIN;
455         pollfd[1].fd = pipefd[cpu*2];
456         pollfd[1].events = POLLIN;
457
458         for (;;) {
459                 ret = poll(pollfd, 2, -1);
460                 if (!ret)
461                         fprintf(stderr, "poll error %d\n", ret), exit(1);
462                 if (ret < 0)
463                         perror("poll"), exit(1);
464                 if (pollfd[1].revents & POLLIN) {
465                         if (read(pollfd[1].fd, &tmp_chr, 1) != 1)
466                                 fprintf(stderr, "read pipefd error\n"),
467                                         exit(1);
468                         break;
469                 }
470                 if (!(pollfd[0].revents & POLLIN))
471                         fprintf(stderr, "pollfd[0].revents %d\n",
472                                 pollfd[0].revents), exit(1);
473                 ret = read(uffd, &msg, sizeof(msg));
474                 if (ret < 0) {
475                         if (errno == EAGAIN)
476                                 continue;
477                         perror("nonblocking read error"), exit(1);
478                 }
479                 switch (msg.event) {
480                 default:
481                         fprintf(stderr, "unexpected msg event %u\n",
482                                 msg.event), exit(1);
483                         break;
484                 case UFFD_EVENT_PAGEFAULT:
485                         if (msg.arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_WRITE)
486                                 fprintf(stderr, "unexpected write fault\n"), exit(1);
487                         offset = (char *)(unsigned long)msg.arg.pagefault.address -
488                                 area_dst;
489                         offset &= ~(page_size-1);
490                         if (copy_page(uffd, offset))
491                                 userfaults++;
492                         break;
493                 case UFFD_EVENT_FORK:
494                         close(uffd);
495                         uffd = msg.arg.fork.ufd;
496                         pollfd[0].fd = uffd;
497                         break;
498                 case UFFD_EVENT_REMOVE:
499                         uffd_reg.range.start = msg.arg.remove.start;
500                         uffd_reg.range.len = msg.arg.remove.end -
501                                 msg.arg.remove.start;
502                         if (ioctl(uffd, UFFDIO_UNREGISTER, &uffd_reg.range))
503                                 fprintf(stderr, "remove failure\n"), exit(1);
504                         break;
505                 case UFFD_EVENT_REMAP:
506                         area_dst = (char *)(unsigned long)msg.arg.remap.to;
507                         break;
508                 }
509         }
510         return (void *)userfaults;
511 }
512
513 pthread_mutex_t uffd_read_mutex = PTHREAD_MUTEX_INITIALIZER;
514
515 static void *uffd_read_thread(void *arg)
516 {
517         unsigned long *this_cpu_userfaults;
518         struct uffd_msg msg;
519         unsigned long offset;
520         int ret;
521
522         this_cpu_userfaults = (unsigned long *) arg;
523         *this_cpu_userfaults = 0;
524
525         pthread_mutex_unlock(&uffd_read_mutex);
526         /* from here cancellation is ok */
527
528         for (;;) {
529                 ret = read(uffd, &msg, sizeof(msg));
530                 if (ret != sizeof(msg)) {
531                         if (ret < 0)
532                                 perror("blocking read error"), exit(1);
533                         else
534                                 fprintf(stderr, "short read\n"), exit(1);
535                 }
536                 if (msg.event != UFFD_EVENT_PAGEFAULT)
537                         fprintf(stderr, "unexpected msg event %u\n",
538                                 msg.event), exit(1);
539                 if (bounces & BOUNCE_VERIFY &&
540                     msg.arg.pagefault.flags & UFFD_PAGEFAULT_FLAG_WRITE)
541                         fprintf(stderr, "unexpected write fault\n"), exit(1);
542                 offset = (char *)(unsigned long)msg.arg.pagefault.address -
543                          area_dst;
544                 offset &= ~(page_size-1);
545                 if (copy_page(uffd, offset))
546                         (*this_cpu_userfaults)++;
547         }
548         return (void *)NULL;
549 }
550
551 static void *background_thread(void *arg)
552 {
553         unsigned long cpu = (unsigned long) arg;
554         unsigned long page_nr;
555
556         for (page_nr = cpu * nr_pages_per_cpu;
557              page_nr < (cpu+1) * nr_pages_per_cpu;
558              page_nr++)
559                 copy_page_retry(uffd, page_nr * page_size);
560
561         return NULL;
562 }
563
564 static int stress(unsigned long *userfaults)
565 {
566         unsigned long cpu;
567         pthread_t locking_threads[nr_cpus];
568         pthread_t uffd_threads[nr_cpus];
569         pthread_t background_threads[nr_cpus];
570         void **_userfaults = (void **) userfaults;
571
572         finished = 0;
573         for (cpu = 0; cpu < nr_cpus; cpu++) {
574                 if (pthread_create(&locking_threads[cpu], &attr,
575                                    locking_thread, (void *)cpu))
576                         return 1;
577                 if (bounces & BOUNCE_POLL) {
578                         if (pthread_create(&uffd_threads[cpu], &attr,
579                                            uffd_poll_thread, (void *)cpu))
580                                 return 1;
581                 } else {
582                         if (pthread_create(&uffd_threads[cpu], &attr,
583                                            uffd_read_thread,
584                                            &_userfaults[cpu]))
585                                 return 1;
586                         pthread_mutex_lock(&uffd_read_mutex);
587                 }
588                 if (pthread_create(&background_threads[cpu], &attr,
589                                    background_thread, (void *)cpu))
590                         return 1;
591         }
592         for (cpu = 0; cpu < nr_cpus; cpu++)
593                 if (pthread_join(background_threads[cpu], NULL))
594                         return 1;
595
596         /*
597          * Be strict and immediately zap area_src, the whole area has
598          * been transferred already by the background treads. The
599          * area_src could then be faulted in in a racy way by still
600          * running uffdio_threads reading zeropages after we zapped
601          * area_src (but they're guaranteed to get -EEXIST from
602          * UFFDIO_COPY without writing zero pages into area_dst
603          * because the background threads already completed).
604          */
605         if (uffd_test_ops->release_pages(area_src))
606                 return 1;
607
608         for (cpu = 0; cpu < nr_cpus; cpu++) {
609                 char c;
610                 if (bounces & BOUNCE_POLL) {
611                         if (write(pipefd[cpu*2+1], &c, 1) != 1) {
612                                 fprintf(stderr, "pipefd write error\n");
613                                 return 1;
614                         }
615                         if (pthread_join(uffd_threads[cpu], &_userfaults[cpu]))
616                                 return 1;
617                 } else {
618                         if (pthread_cancel(uffd_threads[cpu]))
619                                 return 1;
620                         if (pthread_join(uffd_threads[cpu], NULL))
621                                 return 1;
622                 }
623         }
624
625         finished = 1;
626         for (cpu = 0; cpu < nr_cpus; cpu++)
627                 if (pthread_join(locking_threads[cpu], NULL))
628                         return 1;
629
630         return 0;
631 }
632
633 static int userfaultfd_open(int features)
634 {
635         struct uffdio_api uffdio_api;
636
637         uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
638         if (uffd < 0) {
639                 fprintf(stderr,
640                         "userfaultfd syscall not available in this kernel\n");
641                 return 1;
642         }
643         uffd_flags = fcntl(uffd, F_GETFD, NULL);
644
645         uffdio_api.api = UFFD_API;
646         uffdio_api.features = features;
647         if (ioctl(uffd, UFFDIO_API, &uffdio_api)) {
648                 fprintf(stderr, "UFFDIO_API\n");
649                 return 1;
650         }
651         if (uffdio_api.api != UFFD_API) {
652                 fprintf(stderr, "UFFDIO_API error %Lu\n", uffdio_api.api);
653                 return 1;
654         }
655
656         return 0;
657 }
658
659 sigjmp_buf jbuf, *sigbuf;
660
661 static void sighndl(int sig, siginfo_t *siginfo, void *ptr)
662 {
663         if (sig == SIGBUS) {
664                 if (sigbuf)
665                         siglongjmp(*sigbuf, 1);
666                 abort();
667         }
668 }
669
670 /*
671  * For non-cooperative userfaultfd test we fork() a process that will
672  * generate pagefaults, will mremap the area monitored by the
673  * userfaultfd and at last this process will release the monitored
674  * area.
675  * For the anonymous and shared memory the area is divided into two
676  * parts, the first part is accessed before mremap, and the second
677  * part is accessed after mremap. Since hugetlbfs does not support
678  * mremap, the entire monitored area is accessed in a single pass for
679  * HUGETLB_TEST.
680  * The release of the pages currently generates event for shmem and
681  * anonymous memory (UFFD_EVENT_REMOVE), hence it is not checked
682  * for hugetlb.
683  * For signal test(UFFD_FEATURE_SIGBUS), signal_test = 1, we register
684  * monitored area, generate pagefaults and test that signal is delivered.
685  * Use UFFDIO_COPY to allocate missing page and retry. For signal_test = 2
686  * test robustness use case - we release monitored area, fork a process
687  * that will generate pagefaults and verify signal is generated.
688  * This also tests UFFD_FEATURE_EVENT_FORK event along with the signal
689  * feature. Using monitor thread, verify no userfault events are generated.
690  */
691 static int faulting_process(int signal_test)
692 {
693         unsigned long nr;
694         unsigned long long count;
695         unsigned long split_nr_pages;
696         unsigned long lastnr;
697         struct sigaction act;
698         unsigned long signalled = 0;
699
700         if (test_type != TEST_HUGETLB)
701                 split_nr_pages = (nr_pages + 1) / 2;
702         else
703                 split_nr_pages = nr_pages;
704
705         if (signal_test) {
706                 sigbuf = &jbuf;
707                 memset(&act, 0, sizeof(act));
708                 act.sa_sigaction = sighndl;
709                 act.sa_flags = SA_SIGINFO;
710                 if (sigaction(SIGBUS, &act, 0)) {
711                         perror("sigaction");
712                         return 1;
713                 }
714                 lastnr = (unsigned long)-1;
715         }
716
717         for (nr = 0; nr < split_nr_pages; nr++) {
718                 if (signal_test) {
719                         if (sigsetjmp(*sigbuf, 1) != 0) {
720                                 if (nr == lastnr) {
721                                         fprintf(stderr, "Signal repeated\n");
722                                         return 1;
723                                 }
724
725                                 lastnr = nr;
726                                 if (signal_test == 1) {
727                                         if (copy_page(uffd, nr * page_size))
728                                                 signalled++;
729                                 } else {
730                                         signalled++;
731                                         continue;
732                                 }
733                         }
734                 }
735
736                 count = *area_count(area_dst, nr);
737                 if (count != count_verify[nr]) {
738                         fprintf(stderr,
739                                 "nr %lu memory corruption %Lu %Lu\n",
740                                 nr, count,
741                                 count_verify[nr]), exit(1);
742                 }
743         }
744
745         if (signal_test)
746                 return signalled != split_nr_pages;
747
748         if (test_type == TEST_HUGETLB)
749                 return 0;
750
751         area_dst = mremap(area_dst, nr_pages * page_size,  nr_pages * page_size,
752                           MREMAP_MAYMOVE | MREMAP_FIXED, area_src);
753         if (area_dst == MAP_FAILED)
754                 perror("mremap"), exit(1);
755
756         for (; nr < nr_pages; nr++) {
757                 count = *area_count(area_dst, nr);
758                 if (count != count_verify[nr]) {
759                         fprintf(stderr,
760                                 "nr %lu memory corruption %Lu %Lu\n",
761                                 nr, count,
762                                 count_verify[nr]), exit(1);
763                 }
764         }
765
766         if (uffd_test_ops->release_pages(area_dst))
767                 return 1;
768
769         for (nr = 0; nr < nr_pages; nr++) {
770                 if (my_bcmp(area_dst + nr * page_size, zeropage, page_size))
771                         fprintf(stderr, "nr %lu is not zero\n", nr), exit(1);
772         }
773
774         return 0;
775 }
776
777 static void retry_uffdio_zeropage(int ufd,
778                                   struct uffdio_zeropage *uffdio_zeropage,
779                                   unsigned long offset)
780 {
781         uffd_test_ops->alias_mapping(&uffdio_zeropage->range.start,
782                                      uffdio_zeropage->range.len,
783                                      offset);
784         if (ioctl(ufd, UFFDIO_ZEROPAGE, uffdio_zeropage)) {
785                 if (uffdio_zeropage->zeropage != -EEXIST)
786                         fprintf(stderr, "UFFDIO_ZEROPAGE retry error %Ld\n",
787                                 uffdio_zeropage->zeropage), exit(1);
788         } else {
789                 fprintf(stderr, "UFFDIO_ZEROPAGE retry unexpected %Ld\n",
790                         uffdio_zeropage->zeropage), exit(1);
791         }
792 }
793
794 static int __uffdio_zeropage(int ufd, unsigned long offset, bool retry)
795 {
796         struct uffdio_zeropage uffdio_zeropage;
797         int ret;
798         unsigned long has_zeropage;
799
800         has_zeropage = uffd_test_ops->expected_ioctls & (1 << _UFFDIO_ZEROPAGE);
801
802         if (offset >= nr_pages * page_size)
803                 fprintf(stderr, "unexpected offset %lu\n",
804                         offset), exit(1);
805         uffdio_zeropage.range.start = (unsigned long) area_dst + offset;
806         uffdio_zeropage.range.len = page_size;
807         uffdio_zeropage.mode = 0;
808         ret = ioctl(ufd, UFFDIO_ZEROPAGE, &uffdio_zeropage);
809         if (ret) {
810                 /* real retval in ufdio_zeropage.zeropage */
811                 if (has_zeropage) {
812                         if (uffdio_zeropage.zeropage == -EEXIST)
813                                 fprintf(stderr, "UFFDIO_ZEROPAGE -EEXIST\n"),
814                                         exit(1);
815                         else
816                                 fprintf(stderr, "UFFDIO_ZEROPAGE error %Ld\n",
817                                         uffdio_zeropage.zeropage), exit(1);
818                 } else {
819                         if (uffdio_zeropage.zeropage != -EINVAL)
820                                 fprintf(stderr,
821                                         "UFFDIO_ZEROPAGE not -EINVAL %Ld\n",
822                                         uffdio_zeropage.zeropage), exit(1);
823                 }
824         } else if (has_zeropage) {
825                 if (uffdio_zeropage.zeropage != page_size) {
826                         fprintf(stderr, "UFFDIO_ZEROPAGE unexpected %Ld\n",
827                                 uffdio_zeropage.zeropage), exit(1);
828                 } else {
829                         if (test_uffdio_zeropage_eexist && retry) {
830                                 test_uffdio_zeropage_eexist = false;
831                                 retry_uffdio_zeropage(ufd, &uffdio_zeropage,
832                                                       offset);
833                         }
834                         return 1;
835                 }
836         } else {
837                 fprintf(stderr,
838                         "UFFDIO_ZEROPAGE succeeded %Ld\n",
839                         uffdio_zeropage.zeropage), exit(1);
840         }
841
842         return 0;
843 }
844
845 static int uffdio_zeropage(int ufd, unsigned long offset)
846 {
847         return __uffdio_zeropage(ufd, offset, false);
848 }
849
850 /* exercise UFFDIO_ZEROPAGE */
851 static int userfaultfd_zeropage_test(void)
852 {
853         struct uffdio_register uffdio_register;
854         unsigned long expected_ioctls;
855
856         printf("testing UFFDIO_ZEROPAGE: ");
857         fflush(stdout);
858
859         if (uffd_test_ops->release_pages(area_dst))
860                 return 1;
861
862         if (userfaultfd_open(0) < 0)
863                 return 1;
864         uffdio_register.range.start = (unsigned long) area_dst;
865         uffdio_register.range.len = nr_pages * page_size;
866         uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
867         if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register))
868                 fprintf(stderr, "register failure\n"), exit(1);
869
870         expected_ioctls = uffd_test_ops->expected_ioctls;
871         if ((uffdio_register.ioctls & expected_ioctls) !=
872             expected_ioctls)
873                 fprintf(stderr,
874                         "unexpected missing ioctl for anon memory\n"),
875                         exit(1);
876
877         if (uffdio_zeropage(uffd, 0)) {
878                 if (my_bcmp(area_dst, zeropage, page_size))
879                         fprintf(stderr, "zeropage is not zero\n"), exit(1);
880         }
881
882         close(uffd);
883         printf("done.\n");
884         return 0;
885 }
886
887 static int userfaultfd_events_test(void)
888 {
889         struct uffdio_register uffdio_register;
890         unsigned long expected_ioctls;
891         unsigned long userfaults;
892         pthread_t uffd_mon;
893         int err, features;
894         pid_t pid;
895         char c;
896
897         printf("testing events (fork, remap, remove): ");
898         fflush(stdout);
899
900         if (uffd_test_ops->release_pages(area_dst))
901                 return 1;
902
903         features = UFFD_FEATURE_EVENT_FORK | UFFD_FEATURE_EVENT_REMAP |
904                 UFFD_FEATURE_EVENT_REMOVE;
905         if (userfaultfd_open(features) < 0)
906                 return 1;
907         fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
908
909         uffdio_register.range.start = (unsigned long) area_dst;
910         uffdio_register.range.len = nr_pages * page_size;
911         uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
912         if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register))
913                 fprintf(stderr, "register failure\n"), exit(1);
914
915         expected_ioctls = uffd_test_ops->expected_ioctls;
916         if ((uffdio_register.ioctls & expected_ioctls) !=
917             expected_ioctls)
918                 fprintf(stderr,
919                         "unexpected missing ioctl for anon memory\n"),
920                         exit(1);
921
922         if (pthread_create(&uffd_mon, &attr, uffd_poll_thread, NULL))
923                 perror("uffd_poll_thread create"), exit(1);
924
925         pid = fork();
926         if (pid < 0)
927                 perror("fork"), exit(1);
928
929         if (!pid)
930                 return faulting_process(0);
931
932         waitpid(pid, &err, 0);
933         if (err)
934                 fprintf(stderr, "faulting process failed\n"), exit(1);
935
936         if (write(pipefd[1], &c, sizeof(c)) != sizeof(c))
937                 perror("pipe write"), exit(1);
938         if (pthread_join(uffd_mon, (void **)&userfaults))
939                 return 1;
940
941         close(uffd);
942         printf("userfaults: %ld\n", userfaults);
943
944         return userfaults != nr_pages;
945 }
946
947 static int userfaultfd_sig_test(void)
948 {
949         struct uffdio_register uffdio_register;
950         unsigned long expected_ioctls;
951         unsigned long userfaults;
952         pthread_t uffd_mon;
953         int err, features;
954         pid_t pid;
955         char c;
956
957         printf("testing signal delivery: ");
958         fflush(stdout);
959
960         if (uffd_test_ops->release_pages(area_dst))
961                 return 1;
962
963         features = UFFD_FEATURE_EVENT_FORK|UFFD_FEATURE_SIGBUS;
964         if (userfaultfd_open(features) < 0)
965                 return 1;
966         fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
967
968         uffdio_register.range.start = (unsigned long) area_dst;
969         uffdio_register.range.len = nr_pages * page_size;
970         uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
971         if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register))
972                 fprintf(stderr, "register failure\n"), exit(1);
973
974         expected_ioctls = uffd_test_ops->expected_ioctls;
975         if ((uffdio_register.ioctls & expected_ioctls) !=
976             expected_ioctls)
977                 fprintf(stderr,
978                         "unexpected missing ioctl for anon memory\n"),
979                         exit(1);
980
981         if (faulting_process(1))
982                 fprintf(stderr, "faulting process failed\n"), exit(1);
983
984         if (uffd_test_ops->release_pages(area_dst))
985                 return 1;
986
987         if (pthread_create(&uffd_mon, &attr, uffd_poll_thread, NULL))
988                 perror("uffd_poll_thread create"), exit(1);
989
990         pid = fork();
991         if (pid < 0)
992                 perror("fork"), exit(1);
993
994         if (!pid)
995                 exit(faulting_process(2));
996
997         waitpid(pid, &err, 0);
998         if (err)
999                 fprintf(stderr, "faulting process failed\n"), exit(1);
1000
1001         if (write(pipefd[1], &c, sizeof(c)) != sizeof(c))
1002                 perror("pipe write"), exit(1);
1003         if (pthread_join(uffd_mon, (void **)&userfaults))
1004                 return 1;
1005
1006         printf("done.\n");
1007         if (userfaults)
1008                 fprintf(stderr, "Signal test failed, userfaults: %ld\n",
1009                         userfaults);
1010         close(uffd);
1011         return userfaults != 0;
1012 }
1013 static int userfaultfd_stress(void)
1014 {
1015         void *area;
1016         char *tmp_area;
1017         unsigned long nr;
1018         struct uffdio_register uffdio_register;
1019         unsigned long cpu;
1020         int err;
1021         unsigned long userfaults[nr_cpus];
1022
1023         uffd_test_ops->allocate_area((void **)&area_src);
1024         if (!area_src)
1025                 return 1;
1026         uffd_test_ops->allocate_area((void **)&area_dst);
1027         if (!area_dst)
1028                 return 1;
1029
1030         if (userfaultfd_open(0) < 0)
1031                 return 1;
1032
1033         count_verify = malloc(nr_pages * sizeof(unsigned long long));
1034         if (!count_verify) {
1035                 perror("count_verify");
1036                 return 1;
1037         }
1038
1039         for (nr = 0; nr < nr_pages; nr++) {
1040                 *area_mutex(area_src, nr) = (pthread_mutex_t)
1041                         PTHREAD_MUTEX_INITIALIZER;
1042                 count_verify[nr] = *area_count(area_src, nr) = 1;
1043                 /*
1044                  * In the transition between 255 to 256, powerpc will
1045                  * read out of order in my_bcmp and see both bytes as
1046                  * zero, so leave a placeholder below always non-zero
1047                  * after the count, to avoid my_bcmp to trigger false
1048                  * positives.
1049                  */
1050                 *(area_count(area_src, nr) + 1) = 1;
1051         }
1052
1053         pipefd = malloc(sizeof(int) * nr_cpus * 2);
1054         if (!pipefd) {
1055                 perror("pipefd");
1056                 return 1;
1057         }
1058         for (cpu = 0; cpu < nr_cpus; cpu++) {
1059                 if (pipe2(&pipefd[cpu*2], O_CLOEXEC | O_NONBLOCK)) {
1060                         perror("pipe");
1061                         return 1;
1062                 }
1063         }
1064
1065         if (posix_memalign(&area, page_size, page_size)) {
1066                 fprintf(stderr, "out of memory\n");
1067                 return 1;
1068         }
1069         zeropage = area;
1070         bzero(zeropage, page_size);
1071
1072         pthread_mutex_lock(&uffd_read_mutex);
1073
1074         pthread_attr_init(&attr);
1075         pthread_attr_setstacksize(&attr, 16*1024*1024);
1076
1077         err = 0;
1078         while (bounces--) {
1079                 unsigned long expected_ioctls;
1080
1081                 printf("bounces: %d, mode:", bounces);
1082                 if (bounces & BOUNCE_RANDOM)
1083                         printf(" rnd");
1084                 if (bounces & BOUNCE_RACINGFAULTS)
1085                         printf(" racing");
1086                 if (bounces & BOUNCE_VERIFY)
1087                         printf(" ver");
1088                 if (bounces & BOUNCE_POLL)
1089                         printf(" poll");
1090                 printf(", ");
1091                 fflush(stdout);
1092
1093                 if (bounces & BOUNCE_POLL)
1094                         fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
1095                 else
1096                         fcntl(uffd, F_SETFL, uffd_flags & ~O_NONBLOCK);
1097
1098                 /* register */
1099                 uffdio_register.range.start = (unsigned long) area_dst;
1100                 uffdio_register.range.len = nr_pages * page_size;
1101                 uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
1102                 if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register)) {
1103                         fprintf(stderr, "register failure\n");
1104                         return 1;
1105                 }
1106                 expected_ioctls = uffd_test_ops->expected_ioctls;
1107                 if ((uffdio_register.ioctls & expected_ioctls) !=
1108                     expected_ioctls) {
1109                         fprintf(stderr,
1110                                 "unexpected missing ioctl for anon memory\n");
1111                         return 1;
1112                 }
1113
1114                 if (area_dst_alias) {
1115                         uffdio_register.range.start = (unsigned long)
1116                                 area_dst_alias;
1117                         if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register)) {
1118                                 fprintf(stderr, "register failure alias\n");
1119                                 return 1;
1120                         }
1121                 }
1122
1123                 /*
1124                  * The madvise done previously isn't enough: some
1125                  * uffd_thread could have read userfaults (one of
1126                  * those already resolved by the background thread)
1127                  * and it may be in the process of calling
1128                  * UFFDIO_COPY. UFFDIO_COPY will read the zapped
1129                  * area_src and it would map a zero page in it (of
1130                  * course such a UFFDIO_COPY is perfectly safe as it'd
1131                  * return -EEXIST). The problem comes at the next
1132                  * bounce though: that racing UFFDIO_COPY would
1133                  * generate zeropages in the area_src, so invalidating
1134                  * the previous MADV_DONTNEED. Without this additional
1135                  * MADV_DONTNEED those zeropages leftovers in the
1136                  * area_src would lead to -EEXIST failure during the
1137                  * next bounce, effectively leaving a zeropage in the
1138                  * area_dst.
1139                  *
1140                  * Try to comment this out madvise to see the memory
1141                  * corruption being caught pretty quick.
1142                  *
1143                  * khugepaged is also inhibited to collapse THP after
1144                  * MADV_DONTNEED only after the UFFDIO_REGISTER, so it's
1145                  * required to MADV_DONTNEED here.
1146                  */
1147                 if (uffd_test_ops->release_pages(area_dst))
1148                         return 1;
1149
1150                 /* bounce pass */
1151                 if (stress(userfaults))
1152                         return 1;
1153
1154                 /* unregister */
1155                 if (ioctl(uffd, UFFDIO_UNREGISTER, &uffdio_register.range)) {
1156                         fprintf(stderr, "unregister failure\n");
1157                         return 1;
1158                 }
1159                 if (area_dst_alias) {
1160                         uffdio_register.range.start = (unsigned long) area_dst;
1161                         if (ioctl(uffd, UFFDIO_UNREGISTER,
1162                                   &uffdio_register.range)) {
1163                                 fprintf(stderr, "unregister failure alias\n");
1164                                 return 1;
1165                         }
1166                 }
1167
1168                 /* verification */
1169                 if (bounces & BOUNCE_VERIFY) {
1170                         for (nr = 0; nr < nr_pages; nr++) {
1171                                 if (*area_count(area_dst, nr) != count_verify[nr]) {
1172                                         fprintf(stderr,
1173                                                 "error area_count %Lu %Lu %lu\n",
1174                                                 *area_count(area_src, nr),
1175                                                 count_verify[nr],
1176                                                 nr);
1177                                         err = 1;
1178                                         bounces = 0;
1179                                 }
1180                         }
1181                 }
1182
1183                 /* prepare next bounce */
1184                 tmp_area = area_src;
1185                 area_src = area_dst;
1186                 area_dst = tmp_area;
1187
1188                 tmp_area = area_src_alias;
1189                 area_src_alias = area_dst_alias;
1190                 area_dst_alias = tmp_area;
1191
1192                 printf("userfaults:");
1193                 for (cpu = 0; cpu < nr_cpus; cpu++)
1194                         printf(" %lu", userfaults[cpu]);
1195                 printf("\n");
1196         }
1197
1198         if (err)
1199                 return err;
1200
1201         close(uffd);
1202         return userfaultfd_zeropage_test() || userfaultfd_sig_test()
1203                 || userfaultfd_events_test();
1204 }
1205
1206 /*
1207  * Copied from mlock2-tests.c
1208  */
1209 unsigned long default_huge_page_size(void)
1210 {
1211         unsigned long hps = 0;
1212         char *line = NULL;
1213         size_t linelen = 0;
1214         FILE *f = fopen("/proc/meminfo", "r");
1215
1216         if (!f)
1217                 return 0;
1218         while (getline(&line, &linelen, f) > 0) {
1219                 if (sscanf(line, "Hugepagesize:       %lu kB", &hps) == 1) {
1220                         hps <<= 10;
1221                         break;
1222                 }
1223         }
1224
1225         free(line);
1226         fclose(f);
1227         return hps;
1228 }
1229
1230 static void set_test_type(const char *type)
1231 {
1232         if (!strcmp(type, "anon")) {
1233                 test_type = TEST_ANON;
1234                 uffd_test_ops = &anon_uffd_test_ops;
1235         } else if (!strcmp(type, "hugetlb")) {
1236                 test_type = TEST_HUGETLB;
1237                 uffd_test_ops = &hugetlb_uffd_test_ops;
1238         } else if (!strcmp(type, "hugetlb_shared")) {
1239                 map_shared = true;
1240                 test_type = TEST_HUGETLB;
1241                 uffd_test_ops = &hugetlb_uffd_test_ops;
1242         } else if (!strcmp(type, "shmem")) {
1243                 map_shared = true;
1244                 test_type = TEST_SHMEM;
1245                 uffd_test_ops = &shmem_uffd_test_ops;
1246         } else {
1247                 fprintf(stderr, "Unknown test type: %s\n", type), exit(1);
1248         }
1249
1250         if (test_type == TEST_HUGETLB)
1251                 page_size = default_huge_page_size();
1252         else
1253                 page_size = sysconf(_SC_PAGE_SIZE);
1254
1255         if (!page_size)
1256                 fprintf(stderr, "Unable to determine page size\n"),
1257                                 exit(2);
1258         if ((unsigned long) area_count(NULL, 0) + sizeof(unsigned long long) * 2
1259             > page_size)
1260                 fprintf(stderr, "Impossible to run this test\n"), exit(2);
1261 }
1262
1263 static void sigalrm(int sig)
1264 {
1265         if (sig != SIGALRM)
1266                 abort();
1267         test_uffdio_copy_eexist = true;
1268         test_uffdio_zeropage_eexist = true;
1269         alarm(ALARM_INTERVAL_SECS);
1270 }
1271
1272 int main(int argc, char **argv)
1273 {
1274         if (argc < 4)
1275                 fprintf(stderr, "Usage: <test type> <MiB> <bounces> [hugetlbfs_file]\n"),
1276                                 exit(1);
1277
1278         if (signal(SIGALRM, sigalrm) == SIG_ERR)
1279                 fprintf(stderr, "failed to arm SIGALRM"), exit(1);
1280         alarm(ALARM_INTERVAL_SECS);
1281
1282         set_test_type(argv[1]);
1283
1284         nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
1285         nr_pages_per_cpu = atol(argv[2]) * 1024*1024 / page_size /
1286                 nr_cpus;
1287         if (!nr_pages_per_cpu) {
1288                 fprintf(stderr, "invalid MiB\n");
1289                 fprintf(stderr, "Usage: <MiB> <bounces>\n"), exit(1);
1290         }
1291
1292         bounces = atoi(argv[3]);
1293         if (bounces <= 0) {
1294                 fprintf(stderr, "invalid bounces\n");
1295                 fprintf(stderr, "Usage: <MiB> <bounces>\n"), exit(1);
1296         }
1297         nr_pages = nr_pages_per_cpu * nr_cpus;
1298
1299         if (test_type == TEST_HUGETLB) {
1300                 if (argc < 5)
1301                         fprintf(stderr, "Usage: hugetlb <MiB> <bounces> <hugetlbfs_file>\n"),
1302                                 exit(1);
1303                 huge_fd = open(argv[4], O_CREAT | O_RDWR, 0755);
1304                 if (huge_fd < 0) {
1305                         fprintf(stderr, "Open of %s failed", argv[3]);
1306                         perror("open");
1307                         exit(1);
1308                 }
1309                 if (ftruncate(huge_fd, 0)) {
1310                         fprintf(stderr, "ftruncate %s to size 0 failed", argv[3]);
1311                         perror("ftruncate");
1312                         exit(1);
1313                 }
1314         }
1315         printf("nr_pages: %lu, nr_pages_per_cpu: %lu\n",
1316                nr_pages, nr_pages_per_cpu);
1317         return userfaultfd_stress();
1318 }
1319
1320 #else /* __NR_userfaultfd */
1321
1322 #warning "missing __NR_userfaultfd definition"
1323
1324 int main(void)
1325 {
1326         printf("skip: Skipping userfaultfd test (missing __NR_userfaultfd)\n");
1327         return KSFT_SKIP;
1328 }
1329
1330 #endif /* __NR_userfaultfd */