xref: /openbmc/linux/lib/test_lockup.c (revision 6a1c70de)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Test module to generate lockups
4  */
5 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
6 
7 #include <linux/kernel.h>
8 #include <linux/module.h>
9 #include <linux/delay.h>
10 #include <linux/sched.h>
11 #include <linux/sched/signal.h>
12 #include <linux/sched/clock.h>
13 #include <linux/cpu.h>
14 #include <linux/nmi.h>
15 #include <linux/mm.h>
16 #include <linux/uaccess.h>
17 #include <linux/file.h>
18 
19 static unsigned int time_secs;
20 module_param(time_secs, uint, 0600);
21 MODULE_PARM_DESC(time_secs, "lockup time in seconds, default 0");
22 
23 static unsigned int time_nsecs;
24 module_param(time_nsecs, uint, 0600);
25 MODULE_PARM_DESC(time_nsecs, "nanoseconds part of lockup time, default 0");
26 
27 static unsigned int cooldown_secs;
28 module_param(cooldown_secs, uint, 0600);
29 MODULE_PARM_DESC(cooldown_secs, "cooldown time between iterations in seconds, default 0");
30 
31 static unsigned int cooldown_nsecs;
32 module_param(cooldown_nsecs, uint, 0600);
33 MODULE_PARM_DESC(cooldown_nsecs, "nanoseconds part of cooldown, default 0");
34 
35 static unsigned int iterations = 1;
36 module_param(iterations, uint, 0600);
37 MODULE_PARM_DESC(iterations, "lockup iterations, default 1");
38 
39 static bool all_cpus;
40 module_param(all_cpus, bool, 0400);
41 MODULE_PARM_DESC(all_cpus, "trigger lockup at all cpus at once");
42 
43 static int wait_state;
44 static char *state = "R";
45 module_param(state, charp, 0400);
46 MODULE_PARM_DESC(state, "wait in 'R' running (default), 'D' uninterruptible, 'K' killable, 'S' interruptible state");
47 
48 static bool use_hrtimer;
49 module_param(use_hrtimer, bool, 0400);
50 MODULE_PARM_DESC(use_hrtimer, "use high-resolution timer for sleeping");
51 
52 static bool iowait;
53 module_param(iowait, bool, 0400);
54 MODULE_PARM_DESC(iowait, "account sleep time as iowait");
55 
56 static bool lock_read;
57 module_param(lock_read, bool, 0400);
58 MODULE_PARM_DESC(lock_read, "lock read-write locks for read");
59 
60 static bool lock_single;
61 module_param(lock_single, bool, 0400);
62 MODULE_PARM_DESC(lock_single, "acquire locks only at one cpu");
63 
64 static bool reacquire_locks;
65 module_param(reacquire_locks, bool, 0400);
66 MODULE_PARM_DESC(reacquire_locks, "release and reacquire locks/irq/preempt between iterations");
67 
68 static bool touch_softlockup;
69 module_param(touch_softlockup, bool, 0600);
70 MODULE_PARM_DESC(touch_softlockup, "touch soft-lockup watchdog between iterations");
71 
72 static bool touch_hardlockup;
73 module_param(touch_hardlockup, bool, 0600);
74 MODULE_PARM_DESC(touch_hardlockup, "touch hard-lockup watchdog between iterations");
75 
76 static bool call_cond_resched;
77 module_param(call_cond_resched, bool, 0600);
78 MODULE_PARM_DESC(call_cond_resched, "call cond_resched() between iterations");
79 
80 static bool measure_lock_wait;
81 module_param(measure_lock_wait, bool, 0400);
82 MODULE_PARM_DESC(measure_lock_wait, "measure lock wait time");
83 
84 static unsigned long lock_wait_threshold = ULONG_MAX;
85 module_param(lock_wait_threshold, ulong, 0400);
86 MODULE_PARM_DESC(lock_wait_threshold, "print lock wait time longer than this in nanoseconds, default off");
87 
88 static bool test_disable_irq;
89 module_param_named(disable_irq, test_disable_irq, bool, 0400);
90 MODULE_PARM_DESC(disable_irq, "disable interrupts: generate hard-lockups");
91 
92 static bool disable_softirq;
93 module_param(disable_softirq, bool, 0400);
94 MODULE_PARM_DESC(disable_softirq, "disable bottom-half irq handlers");
95 
96 static bool disable_preempt;
97 module_param(disable_preempt, bool, 0400);
98 MODULE_PARM_DESC(disable_preempt, "disable preemption: generate soft-lockups");
99 
100 static bool lock_rcu;
101 module_param(lock_rcu, bool, 0400);
102 MODULE_PARM_DESC(lock_rcu, "grab rcu_read_lock: generate rcu stalls");
103 
104 static bool lock_mmap_sem;
105 module_param(lock_mmap_sem, bool, 0400);
106 MODULE_PARM_DESC(lock_mmap_sem, "lock mm->mmap_lock: block procfs interfaces");
107 
108 static unsigned long lock_rwsem_ptr;
109 module_param_unsafe(lock_rwsem_ptr, ulong, 0400);
110 MODULE_PARM_DESC(lock_rwsem_ptr, "lock rw_semaphore at address");
111 
112 static unsigned long lock_mutex_ptr;
113 module_param_unsafe(lock_mutex_ptr, ulong, 0400);
114 MODULE_PARM_DESC(lock_mutex_ptr, "lock mutex at address");
115 
116 static unsigned long lock_spinlock_ptr;
117 module_param_unsafe(lock_spinlock_ptr, ulong, 0400);
118 MODULE_PARM_DESC(lock_spinlock_ptr, "lock spinlock at address");
119 
120 static unsigned long lock_rwlock_ptr;
121 module_param_unsafe(lock_rwlock_ptr, ulong, 0400);
122 MODULE_PARM_DESC(lock_rwlock_ptr, "lock rwlock at address");
123 
124 static unsigned int alloc_pages_nr;
125 module_param_unsafe(alloc_pages_nr, uint, 0600);
126 MODULE_PARM_DESC(alloc_pages_nr, "allocate and free pages under locks");
127 
128 static unsigned int alloc_pages_order;
129 module_param(alloc_pages_order, uint, 0400);
130 MODULE_PARM_DESC(alloc_pages_order, "page order to allocate");
131 
132 static gfp_t alloc_pages_gfp = GFP_KERNEL;
133 module_param_unsafe(alloc_pages_gfp, uint, 0400);
134 MODULE_PARM_DESC(alloc_pages_gfp, "allocate pages with this gfp_mask, default GFP_KERNEL");
135 
136 static bool alloc_pages_atomic;
137 module_param(alloc_pages_atomic, bool, 0400);
138 MODULE_PARM_DESC(alloc_pages_atomic, "allocate pages with GFP_ATOMIC");
139 
140 static bool reallocate_pages;
141 module_param(reallocate_pages, bool, 0400);
142 MODULE_PARM_DESC(reallocate_pages, "free and allocate pages between iterations");
143 
144 struct file *test_file;
145 static struct inode *test_inode;
146 static char test_file_path[256];
147 module_param_string(file_path, test_file_path, sizeof(test_file_path), 0400);
148 MODULE_PARM_DESC(file_path, "file path to test");
149 
150 static bool test_lock_inode;
151 module_param_named(lock_inode, test_lock_inode, bool, 0400);
152 MODULE_PARM_DESC(lock_inode, "lock file -> inode -> i_rwsem");
153 
154 static bool test_lock_mapping;
155 module_param_named(lock_mapping, test_lock_mapping, bool, 0400);
156 MODULE_PARM_DESC(lock_mapping, "lock file -> mapping -> i_mmap_rwsem");
157 
158 static bool test_lock_sb_umount;
159 module_param_named(lock_sb_umount, test_lock_sb_umount, bool, 0400);
160 MODULE_PARM_DESC(lock_sb_umount, "lock file -> sb -> s_umount");
161 
162 static atomic_t alloc_pages_failed = ATOMIC_INIT(0);
163 
164 static atomic64_t max_lock_wait = ATOMIC64_INIT(0);
165 
166 static struct task_struct *main_task;
167 static int master_cpu;
168 
test_lock(bool master,bool verbose)169 static void test_lock(bool master, bool verbose)
170 {
171 	u64 wait_start;
172 
173 	if (measure_lock_wait)
174 		wait_start = local_clock();
175 
176 	if (lock_mutex_ptr && master) {
177 		if (verbose)
178 			pr_notice("lock mutex %ps\n", (void *)lock_mutex_ptr);
179 		mutex_lock((struct mutex *)lock_mutex_ptr);
180 	}
181 
182 	if (lock_rwsem_ptr && master) {
183 		if (verbose)
184 			pr_notice("lock rw_semaphore %ps\n",
185 				  (void *)lock_rwsem_ptr);
186 		if (lock_read)
187 			down_read((struct rw_semaphore *)lock_rwsem_ptr);
188 		else
189 			down_write((struct rw_semaphore *)lock_rwsem_ptr);
190 	}
191 
192 	if (lock_mmap_sem && master) {
193 		if (verbose)
194 			pr_notice("lock mmap_lock pid=%d\n", main_task->pid);
195 		if (lock_read)
196 			mmap_read_lock(main_task->mm);
197 		else
198 			mmap_write_lock(main_task->mm);
199 	}
200 
201 	if (test_disable_irq)
202 		local_irq_disable();
203 
204 	if (disable_softirq)
205 		local_bh_disable();
206 
207 	if (disable_preempt)
208 		preempt_disable();
209 
210 	if (lock_rcu)
211 		rcu_read_lock();
212 
213 	if (lock_spinlock_ptr && master) {
214 		if (verbose)
215 			pr_notice("lock spinlock %ps\n",
216 				  (void *)lock_spinlock_ptr);
217 		spin_lock((spinlock_t *)lock_spinlock_ptr);
218 	}
219 
220 	if (lock_rwlock_ptr && master) {
221 		if (verbose)
222 			pr_notice("lock rwlock %ps\n",
223 				  (void *)lock_rwlock_ptr);
224 		if (lock_read)
225 			read_lock((rwlock_t *)lock_rwlock_ptr);
226 		else
227 			write_lock((rwlock_t *)lock_rwlock_ptr);
228 	}
229 
230 	if (measure_lock_wait) {
231 		s64 cur_wait = local_clock() - wait_start;
232 		s64 max_wait = atomic64_read(&max_lock_wait);
233 
234 		do {
235 			if (cur_wait < max_wait)
236 				break;
237 			max_wait = atomic64_cmpxchg(&max_lock_wait,
238 						    max_wait, cur_wait);
239 		} while (max_wait != cur_wait);
240 
241 		if (cur_wait > lock_wait_threshold)
242 			pr_notice_ratelimited("lock wait %lld ns\n", cur_wait);
243 	}
244 }
245 
test_unlock(bool master,bool verbose)246 static void test_unlock(bool master, bool verbose)
247 {
248 	if (lock_rwlock_ptr && master) {
249 		if (lock_read)
250 			read_unlock((rwlock_t *)lock_rwlock_ptr);
251 		else
252 			write_unlock((rwlock_t *)lock_rwlock_ptr);
253 		if (verbose)
254 			pr_notice("unlock rwlock %ps\n",
255 				  (void *)lock_rwlock_ptr);
256 	}
257 
258 	if (lock_spinlock_ptr && master) {
259 		spin_unlock((spinlock_t *)lock_spinlock_ptr);
260 		if (verbose)
261 			pr_notice("unlock spinlock %ps\n",
262 				  (void *)lock_spinlock_ptr);
263 	}
264 
265 	if (lock_rcu)
266 		rcu_read_unlock();
267 
268 	if (disable_preempt)
269 		preempt_enable();
270 
271 	if (disable_softirq)
272 		local_bh_enable();
273 
274 	if (test_disable_irq)
275 		local_irq_enable();
276 
277 	if (lock_mmap_sem && master) {
278 		if (lock_read)
279 			mmap_read_unlock(main_task->mm);
280 		else
281 			mmap_write_unlock(main_task->mm);
282 		if (verbose)
283 			pr_notice("unlock mmap_lock pid=%d\n", main_task->pid);
284 	}
285 
286 	if (lock_rwsem_ptr && master) {
287 		if (lock_read)
288 			up_read((struct rw_semaphore *)lock_rwsem_ptr);
289 		else
290 			up_write((struct rw_semaphore *)lock_rwsem_ptr);
291 		if (verbose)
292 			pr_notice("unlock rw_semaphore %ps\n",
293 				  (void *)lock_rwsem_ptr);
294 	}
295 
296 	if (lock_mutex_ptr && master) {
297 		mutex_unlock((struct mutex *)lock_mutex_ptr);
298 		if (verbose)
299 			pr_notice("unlock mutex %ps\n",
300 				  (void *)lock_mutex_ptr);
301 	}
302 }
303 
test_alloc_pages(struct list_head * pages)304 static void test_alloc_pages(struct list_head *pages)
305 {
306 	struct page *page;
307 	unsigned int i;
308 
309 	for (i = 0; i < alloc_pages_nr; i++) {
310 		page = alloc_pages(alloc_pages_gfp, alloc_pages_order);
311 		if (!page) {
312 			atomic_inc(&alloc_pages_failed);
313 			break;
314 		}
315 		list_add(&page->lru, pages);
316 	}
317 }
318 
test_free_pages(struct list_head * pages)319 static void test_free_pages(struct list_head *pages)
320 {
321 	struct page *page, *next;
322 
323 	list_for_each_entry_safe(page, next, pages, lru)
324 		__free_pages(page, alloc_pages_order);
325 	INIT_LIST_HEAD(pages);
326 }
327 
test_wait(unsigned int secs,unsigned int nsecs)328 static void test_wait(unsigned int secs, unsigned int nsecs)
329 {
330 	if (wait_state == TASK_RUNNING) {
331 		if (secs)
332 			mdelay(secs * MSEC_PER_SEC);
333 		if (nsecs)
334 			ndelay(nsecs);
335 		return;
336 	}
337 
338 	__set_current_state(wait_state);
339 	if (use_hrtimer) {
340 		ktime_t time;
341 
342 		time = ns_to_ktime((u64)secs * NSEC_PER_SEC + nsecs);
343 		schedule_hrtimeout(&time, HRTIMER_MODE_REL);
344 	} else {
345 		schedule_timeout(secs * HZ + nsecs_to_jiffies(nsecs));
346 	}
347 }
348 
test_lockup(bool master)349 static void test_lockup(bool master)
350 {
351 	u64 lockup_start = local_clock();
352 	unsigned int iter = 0;
353 	LIST_HEAD(pages);
354 
355 	pr_notice("Start on CPU%d\n", raw_smp_processor_id());
356 
357 	test_lock(master, true);
358 
359 	test_alloc_pages(&pages);
360 
361 	while (iter++ < iterations && !signal_pending(main_task)) {
362 
363 		if (iowait)
364 			current->in_iowait = 1;
365 
366 		test_wait(time_secs, time_nsecs);
367 
368 		if (iowait)
369 			current->in_iowait = 0;
370 
371 		if (reallocate_pages)
372 			test_free_pages(&pages);
373 
374 		if (reacquire_locks)
375 			test_unlock(master, false);
376 
377 		if (touch_softlockup)
378 			touch_softlockup_watchdog();
379 
380 		if (touch_hardlockup)
381 			touch_nmi_watchdog();
382 
383 		if (call_cond_resched)
384 			cond_resched();
385 
386 		test_wait(cooldown_secs, cooldown_nsecs);
387 
388 		if (reacquire_locks)
389 			test_lock(master, false);
390 
391 		if (reallocate_pages)
392 			test_alloc_pages(&pages);
393 	}
394 
395 	pr_notice("Finish on CPU%d in %lld ns\n", raw_smp_processor_id(),
396 		  local_clock() - lockup_start);
397 
398 	test_free_pages(&pages);
399 
400 	test_unlock(master, true);
401 }
402 
403 static DEFINE_PER_CPU(struct work_struct, test_works);
404 
test_work_fn(struct work_struct * work)405 static void test_work_fn(struct work_struct *work)
406 {
407 	test_lockup(!lock_single ||
408 		    work == per_cpu_ptr(&test_works, master_cpu));
409 }
410 
test_kernel_ptr(unsigned long addr,int size)411 static bool test_kernel_ptr(unsigned long addr, int size)
412 {
413 	void *ptr = (void *)addr;
414 	char buf;
415 
416 	if (!addr)
417 		return false;
418 
419 	/* should be at least readable kernel address */
420 	if (!IS_ENABLED(CONFIG_ALTERNATE_USER_ADDRESS_SPACE) &&
421 	    (access_ok((void __user *)ptr, 1) ||
422 	     access_ok((void __user *)ptr + size - 1, 1))) {
423 		pr_err("user space ptr invalid in kernel: %#lx\n", addr);
424 		return true;
425 	}
426 
427 	if (get_kernel_nofault(buf, ptr) ||
428 	    get_kernel_nofault(buf, ptr + size - 1)) {
429 		pr_err("invalid kernel ptr: %#lx\n", addr);
430 		return true;
431 	}
432 
433 	return false;
434 }
435 
test_magic(unsigned long addr,int offset,unsigned int expected)436 static bool __maybe_unused test_magic(unsigned long addr, int offset,
437 				      unsigned int expected)
438 {
439 	void *ptr = (void *)addr + offset;
440 	unsigned int magic = 0;
441 
442 	if (!addr)
443 		return false;
444 
445 	if (get_kernel_nofault(magic, ptr) || magic != expected) {
446 		pr_err("invalid magic at %#lx + %#x = %#x, expected %#x\n",
447 		       addr, offset, magic, expected);
448 		return true;
449 	}
450 
451 	return false;
452 }
453 
test_lockup_init(void)454 static int __init test_lockup_init(void)
455 {
456 	u64 test_start = local_clock();
457 
458 	main_task = current;
459 
460 	switch (state[0]) {
461 	case 'S':
462 		wait_state = TASK_INTERRUPTIBLE;
463 		break;
464 	case 'D':
465 		wait_state = TASK_UNINTERRUPTIBLE;
466 		break;
467 	case 'K':
468 		wait_state = TASK_KILLABLE;
469 		break;
470 	case 'R':
471 		wait_state = TASK_RUNNING;
472 		break;
473 	default:
474 		pr_err("unknown state=%s\n", state);
475 		return -EINVAL;
476 	}
477 
478 	if (alloc_pages_atomic)
479 		alloc_pages_gfp = GFP_ATOMIC;
480 
481 	if (test_kernel_ptr(lock_spinlock_ptr, sizeof(spinlock_t)) ||
482 	    test_kernel_ptr(lock_rwlock_ptr, sizeof(rwlock_t)) ||
483 	    test_kernel_ptr(lock_mutex_ptr, sizeof(struct mutex)) ||
484 	    test_kernel_ptr(lock_rwsem_ptr, sizeof(struct rw_semaphore)))
485 		return -EINVAL;
486 
487 #ifdef CONFIG_DEBUG_SPINLOCK
488 #ifdef CONFIG_PREEMPT_RT
489 	if (test_magic(lock_spinlock_ptr,
490 		       offsetof(spinlock_t, lock.wait_lock.magic),
491 		       SPINLOCK_MAGIC) ||
492 	    test_magic(lock_rwlock_ptr,
493 		       offsetof(rwlock_t, rwbase.rtmutex.wait_lock.magic),
494 		       SPINLOCK_MAGIC) ||
495 	    test_magic(lock_mutex_ptr,
496 		       offsetof(struct mutex, rtmutex.wait_lock.magic),
497 		       SPINLOCK_MAGIC) ||
498 	    test_magic(lock_rwsem_ptr,
499 		       offsetof(struct rw_semaphore, rwbase.rtmutex.wait_lock.magic),
500 		       SPINLOCK_MAGIC))
501 		return -EINVAL;
502 #else
503 	if (test_magic(lock_spinlock_ptr,
504 		       offsetof(spinlock_t, rlock.magic),
505 		       SPINLOCK_MAGIC) ||
506 	    test_magic(lock_rwlock_ptr,
507 		       offsetof(rwlock_t, magic),
508 		       RWLOCK_MAGIC) ||
509 	    test_magic(lock_mutex_ptr,
510 		       offsetof(struct mutex, wait_lock.magic),
511 		       SPINLOCK_MAGIC) ||
512 	    test_magic(lock_rwsem_ptr,
513 		       offsetof(struct rw_semaphore, wait_lock.magic),
514 		       SPINLOCK_MAGIC))
515 		return -EINVAL;
516 #endif
517 #endif
518 
519 	if ((wait_state != TASK_RUNNING ||
520 	     (call_cond_resched && !reacquire_locks) ||
521 	     (alloc_pages_nr && gfpflags_allow_blocking(alloc_pages_gfp))) &&
522 	    (test_disable_irq || disable_softirq || disable_preempt ||
523 	     lock_rcu || lock_spinlock_ptr || lock_rwlock_ptr)) {
524 		pr_err("refuse to sleep in atomic context\n");
525 		return -EINVAL;
526 	}
527 
528 	if (lock_mmap_sem && !main_task->mm) {
529 		pr_err("no mm to lock mmap_lock\n");
530 		return -EINVAL;
531 	}
532 
533 	if (test_file_path[0]) {
534 		test_file = filp_open(test_file_path, O_RDONLY, 0);
535 		if (IS_ERR(test_file)) {
536 			pr_err("failed to open %s: %ld\n", test_file_path, PTR_ERR(test_file));
537 			return PTR_ERR(test_file);
538 		}
539 		test_inode = file_inode(test_file);
540 	} else if (test_lock_inode ||
541 		   test_lock_mapping ||
542 		   test_lock_sb_umount) {
543 		pr_err("no file to lock\n");
544 		return -EINVAL;
545 	}
546 
547 	if (test_lock_inode && test_inode)
548 		lock_rwsem_ptr = (unsigned long)&test_inode->i_rwsem;
549 
550 	if (test_lock_mapping && test_file && test_file->f_mapping)
551 		lock_rwsem_ptr = (unsigned long)&test_file->f_mapping->i_mmap_rwsem;
552 
553 	if (test_lock_sb_umount && test_inode)
554 		lock_rwsem_ptr = (unsigned long)&test_inode->i_sb->s_umount;
555 
556 	pr_notice("START pid=%d time=%u +%u ns cooldown=%u +%u ns iterations=%u state=%s %s%s%s%s%s%s%s%s%s%s%s\n",
557 		  main_task->pid, time_secs, time_nsecs,
558 		  cooldown_secs, cooldown_nsecs, iterations, state,
559 		  all_cpus ? "all_cpus " : "",
560 		  iowait ? "iowait " : "",
561 		  test_disable_irq ? "disable_irq " : "",
562 		  disable_softirq ? "disable_softirq " : "",
563 		  disable_preempt ? "disable_preempt " : "",
564 		  lock_rcu ? "lock_rcu " : "",
565 		  lock_read ? "lock_read " : "",
566 		  touch_softlockup ? "touch_softlockup " : "",
567 		  touch_hardlockup ? "touch_hardlockup " : "",
568 		  call_cond_resched ? "call_cond_resched " : "",
569 		  reacquire_locks ? "reacquire_locks " : "");
570 
571 	if (alloc_pages_nr)
572 		pr_notice("ALLOCATE PAGES nr=%u order=%u gfp=%pGg %s\n",
573 			  alloc_pages_nr, alloc_pages_order, &alloc_pages_gfp,
574 			  reallocate_pages ? "reallocate_pages " : "");
575 
576 	if (all_cpus) {
577 		unsigned int cpu;
578 
579 		cpus_read_lock();
580 
581 		preempt_disable();
582 		master_cpu = smp_processor_id();
583 		for_each_online_cpu(cpu) {
584 			INIT_WORK(per_cpu_ptr(&test_works, cpu), test_work_fn);
585 			queue_work_on(cpu, system_highpri_wq,
586 				      per_cpu_ptr(&test_works, cpu));
587 		}
588 		preempt_enable();
589 
590 		for_each_online_cpu(cpu)
591 			flush_work(per_cpu_ptr(&test_works, cpu));
592 
593 		cpus_read_unlock();
594 	} else {
595 		test_lockup(true);
596 	}
597 
598 	if (measure_lock_wait)
599 		pr_notice("Maximum lock wait: %lld ns\n",
600 			  atomic64_read(&max_lock_wait));
601 
602 	if (alloc_pages_nr)
603 		pr_notice("Page allocation failed %u times\n",
604 			  atomic_read(&alloc_pages_failed));
605 
606 	pr_notice("FINISH in %llu ns\n", local_clock() - test_start);
607 
608 	if (test_file)
609 		fput(test_file);
610 
611 	if (signal_pending(main_task))
612 		return -EINTR;
613 
614 	return -EAGAIN;
615 }
616 module_init(test_lockup_init);
617 
618 MODULE_LICENSE("GPL");
619 MODULE_AUTHOR("Konstantin Khlebnikov <khlebnikov@yandex-team.ru>");
620 MODULE_DESCRIPTION("Test module to generate lockups");
621