1 /*
2 * Collaborative memory management interface.
3 *
4 * Copyright (C) 2008 IBM Corporation
5 * Author(s): Brian King (brking@linux.vnet.ibm.com),
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 *
21 */
22
23 #include <linux/ctype.h>
24 #include <linux/delay.h>
25 #include <linux/errno.h>
26 #include <linux/fs.h>
27 #include <linux/gfp.h>
28 #include <linux/init.h>
29 #include <linux/kthread.h>
30 #include <linux/module.h>
31 #include <linux/oom.h>
32 #include <linux/reboot.h>
33 #include <linux/sched.h>
34 #include <linux/stringify.h>
35 #include <linux/swap.h>
36 #include <linux/sysdev.h>
37 #include <asm/firmware.h>
38 #include <asm/hvcall.h>
39 #include <asm/mmu.h>
40 #include <asm/pgalloc.h>
41 #include <asm/uaccess.h>
42 #include <linux/memory.h>
43
44 #include "plpar_wrappers.h"
45
46 #define CMM_DRIVER_VERSION "1.0.0"
47 #define CMM_DEFAULT_DELAY 1
48 #define CMM_HOTPLUG_DELAY 5
49 #define CMM_DEBUG 0
50 #define CMM_DISABLE 0
51 #define CMM_OOM_KB 1024
52 #define CMM_MIN_MEM_MB 256
53 #define KB2PAGES(_p) ((_p)>>(PAGE_SHIFT-10))
54 #define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10))
55 /*
56 * The priority level tries to ensure that this notifier is called as
57 * late as possible to reduce thrashing in the shared memory pool.
58 */
59 #define CMM_MEM_HOTPLUG_PRI 1
60 #define CMM_MEM_ISOLATE_PRI 15
61
62 static unsigned int delay = CMM_DEFAULT_DELAY;
63 static unsigned int hotplug_delay = CMM_HOTPLUG_DELAY;
64 static unsigned int oom_kb = CMM_OOM_KB;
65 static unsigned int cmm_debug = CMM_DEBUG;
66 static unsigned int cmm_disabled = CMM_DISABLE;
67 static unsigned long min_mem_mb = CMM_MIN_MEM_MB;
68 static struct sys_device cmm_sysdev;
69
70 MODULE_AUTHOR("Brian King <brking@linux.vnet.ibm.com>");
71 MODULE_DESCRIPTION("IBM System p Collaborative Memory Manager");
72 MODULE_LICENSE("GPL");
73 MODULE_VERSION(CMM_DRIVER_VERSION);
74
75 module_param_named(delay, delay, uint, S_IRUGO | S_IWUSR);
76 MODULE_PARM_DESC(delay, "Delay (in seconds) between polls to query hypervisor paging requests. "
77 "[Default=" __stringify(CMM_DEFAULT_DELAY) "]");
78 module_param_named(hotplug_delay, hotplug_delay, uint, S_IRUGO | S_IWUSR);
79 MODULE_PARM_DESC(delay, "Delay (in seconds) after memory hotplug remove "
80 "before loaning resumes. "
81 "[Default=" __stringify(CMM_HOTPLUG_DELAY) "]");
82 module_param_named(oom_kb, oom_kb, uint, S_IRUGO | S_IWUSR);
83 MODULE_PARM_DESC(oom_kb, "Amount of memory in kb to free on OOM. "
84 "[Default=" __stringify(CMM_OOM_KB) "]");
85 module_param_named(min_mem_mb, min_mem_mb, ulong, S_IRUGO | S_IWUSR);
86 MODULE_PARM_DESC(min_mem_mb, "Minimum amount of memory (in MB) to not balloon. "
87 "[Default=" __stringify(CMM_MIN_MEM_MB) "]");
88 module_param_named(debug, cmm_debug, uint, S_IRUGO | S_IWUSR);
89 MODULE_PARM_DESC(debug, "Enable module debugging logging. Set to 1 to enable. "
90 "[Default=" __stringify(CMM_DEBUG) "]");
91
92 #define CMM_NR_PAGES ((PAGE_SIZE - sizeof(void *) - sizeof(unsigned long)) / sizeof(unsigned long))
93
94 #define cmm_dbg(...) if (cmm_debug) { printk(KERN_INFO "cmm: "__VA_ARGS__); }
95
96 struct cmm_page_array {
97 struct cmm_page_array *next;
98 unsigned long index;
99 unsigned long page[CMM_NR_PAGES];
100 };
101
102 static unsigned long loaned_pages;
103 static unsigned long loaned_pages_target;
104 static unsigned long oom_freed_pages;
105
106 static struct cmm_page_array *cmm_page_list;
107 static DEFINE_SPINLOCK(cmm_lock);
108
109 static DEFINE_MUTEX(hotplug_mutex);
110 static int hotplug_occurred; /* protected by the hotplug mutex */
111
112 static struct task_struct *cmm_thread_ptr;
113
114 /**
115 * cmm_alloc_pages - Allocate pages and mark them as loaned
116 * @nr: number of pages to allocate
117 *
118 * Return value:
119 * number of pages requested to be allocated which were not
120 **/
cmm_alloc_pages(long nr)121 static long cmm_alloc_pages(long nr)
122 {
123 struct cmm_page_array *pa, *npa;
124 unsigned long addr;
125 long rc;
126
127 cmm_dbg("Begin request for %ld pages\n", nr);
128
129 while (nr) {
130 /* Exit if a hotplug operation is in progress or occurred */
131 if (mutex_trylock(&hotplug_mutex)) {
132 if (hotplug_occurred) {
133 mutex_unlock(&hotplug_mutex);
134 break;
135 }
136 mutex_unlock(&hotplug_mutex);
137 } else {
138 break;
139 }
140
141 addr = __get_free_page(GFP_NOIO | __GFP_NOWARN |
142 __GFP_NORETRY | __GFP_NOMEMALLOC);
143 if (!addr)
144 break;
145 spin_lock(&cmm_lock);
146 pa = cmm_page_list;
147 if (!pa || pa->index >= CMM_NR_PAGES) {
148 /* Need a new page for the page list. */
149 spin_unlock(&cmm_lock);
150 npa = (struct cmm_page_array *)__get_free_page(
151 GFP_NOIO | __GFP_NOWARN |
152 __GFP_NORETRY | __GFP_NOMEMALLOC);
153 if (!npa) {
154 pr_info("%s: Can not allocate new page list\n", __func__);
155 free_page(addr);
156 break;
157 }
158 spin_lock(&cmm_lock);
159 pa = cmm_page_list;
160
161 if (!pa || pa->index >= CMM_NR_PAGES) {
162 npa->next = pa;
163 npa->index = 0;
164 pa = npa;
165 cmm_page_list = pa;
166 } else
167 free_page((unsigned long) npa);
168 }
169
170 if ((rc = plpar_page_set_loaned(__pa(addr)))) {
171 pr_err("%s: Can not set page to loaned. rc=%ld\n", __func__, rc);
172 spin_unlock(&cmm_lock);
173 free_page(addr);
174 break;
175 }
176
177 pa->page[pa->index++] = addr;
178 loaned_pages++;
179 totalram_pages--;
180 spin_unlock(&cmm_lock);
181 nr--;
182 }
183
184 cmm_dbg("End request with %ld pages unfulfilled\n", nr);
185 return nr;
186 }
187
188 /**
189 * cmm_free_pages - Free pages and mark them as active
190 * @nr: number of pages to free
191 *
192 * Return value:
193 * number of pages requested to be freed which were not
194 **/
cmm_free_pages(long nr)195 static long cmm_free_pages(long nr)
196 {
197 struct cmm_page_array *pa;
198 unsigned long addr;
199
200 cmm_dbg("Begin free of %ld pages.\n", nr);
201 spin_lock(&cmm_lock);
202 pa = cmm_page_list;
203 while (nr) {
204 if (!pa || pa->index <= 0)
205 break;
206 addr = pa->page[--pa->index];
207
208 if (pa->index == 0) {
209 pa = pa->next;
210 free_page((unsigned long) cmm_page_list);
211 cmm_page_list = pa;
212 }
213
214 plpar_page_set_active(__pa(addr));
215 free_page(addr);
216 loaned_pages--;
217 nr--;
218 totalram_pages++;
219 }
220 spin_unlock(&cmm_lock);
221 cmm_dbg("End request with %ld pages unfulfilled\n", nr);
222 return nr;
223 }
224
225 /**
226 * cmm_oom_notify - OOM notifier
227 * @self: notifier block struct
228 * @dummy: not used
229 * @parm: returned - number of pages freed
230 *
231 * Return value:
232 * NOTIFY_OK
233 **/
cmm_oom_notify(struct notifier_block * self,unsigned long dummy,void * parm)234 static int cmm_oom_notify(struct notifier_block *self,
235 unsigned long dummy, void *parm)
236 {
237 unsigned long *freed = parm;
238 long nr = KB2PAGES(oom_kb);
239
240 cmm_dbg("OOM processing started\n");
241 nr = cmm_free_pages(nr);
242 loaned_pages_target = loaned_pages;
243 *freed += KB2PAGES(oom_kb) - nr;
244 oom_freed_pages += KB2PAGES(oom_kb) - nr;
245 cmm_dbg("OOM processing complete\n");
246 return NOTIFY_OK;
247 }
248
249 /**
250 * cmm_get_mpp - Read memory performance parameters
251 *
252 * Makes hcall to query the current page loan request from the hypervisor.
253 *
254 * Return value:
255 * nothing
256 **/
cmm_get_mpp(void)257 static void cmm_get_mpp(void)
258 {
259 int rc;
260 struct hvcall_mpp_data mpp_data;
261 signed long active_pages_target, page_loan_request, target;
262 signed long total_pages = totalram_pages + loaned_pages;
263 signed long min_mem_pages = (min_mem_mb * 1024 * 1024) / PAGE_SIZE;
264
265 rc = h_get_mpp(&mpp_data);
266
267 if (rc != H_SUCCESS)
268 return;
269
270 page_loan_request = div_s64((s64)mpp_data.loan_request, PAGE_SIZE);
271 target = page_loan_request + (signed long)loaned_pages;
272
273 if (target < 0 || total_pages < min_mem_pages)
274 target = 0;
275
276 if (target > oom_freed_pages)
277 target -= oom_freed_pages;
278 else
279 target = 0;
280
281 active_pages_target = total_pages - target;
282
283 if (min_mem_pages > active_pages_target)
284 target = total_pages - min_mem_pages;
285
286 if (target < 0)
287 target = 0;
288
289 loaned_pages_target = target;
290
291 cmm_dbg("delta = %ld, loaned = %lu, target = %lu, oom = %lu, totalram = %lu\n",
292 page_loan_request, loaned_pages, loaned_pages_target,
293 oom_freed_pages, totalram_pages);
294 }
295
296 static struct notifier_block cmm_oom_nb = {
297 .notifier_call = cmm_oom_notify
298 };
299
300 /**
301 * cmm_thread - CMM task thread
302 * @dummy: not used
303 *
304 * Return value:
305 * 0
306 **/
cmm_thread(void * dummy)307 static int cmm_thread(void *dummy)
308 {
309 unsigned long timeleft;
310
311 while (1) {
312 timeleft = msleep_interruptible(delay * 1000);
313
314 if (kthread_should_stop() || timeleft)
315 break;
316
317 if (mutex_trylock(&hotplug_mutex)) {
318 if (hotplug_occurred) {
319 hotplug_occurred = 0;
320 mutex_unlock(&hotplug_mutex);
321 cmm_dbg("Hotplug operation has occurred, "
322 "loaning activity suspended "
323 "for %d seconds.\n",
324 hotplug_delay);
325 timeleft = msleep_interruptible(hotplug_delay *
326 1000);
327 if (kthread_should_stop() || timeleft)
328 break;
329 continue;
330 }
331 mutex_unlock(&hotplug_mutex);
332 } else {
333 cmm_dbg("Hotplug operation in progress, activity "
334 "suspended\n");
335 continue;
336 }
337
338 cmm_get_mpp();
339
340 if (loaned_pages_target > loaned_pages) {
341 if (cmm_alloc_pages(loaned_pages_target - loaned_pages))
342 loaned_pages_target = loaned_pages;
343 } else if (loaned_pages_target < loaned_pages)
344 cmm_free_pages(loaned_pages - loaned_pages_target);
345 }
346 return 0;
347 }
348
349 #define CMM_SHOW(name, format, args...) \
350 static ssize_t show_##name(struct sys_device *dev, \
351 struct sysdev_attribute *attr, \
352 char *buf) \
353 { \
354 return sprintf(buf, format, ##args); \
355 } \
356 static SYSDEV_ATTR(name, S_IRUGO, show_##name, NULL)
357
358 CMM_SHOW(loaned_kb, "%lu\n", PAGES2KB(loaned_pages));
359 CMM_SHOW(loaned_target_kb, "%lu\n", PAGES2KB(loaned_pages_target));
360
show_oom_pages(struct sys_device * dev,struct sysdev_attribute * attr,char * buf)361 static ssize_t show_oom_pages(struct sys_device *dev,
362 struct sysdev_attribute *attr, char *buf)
363 {
364 return sprintf(buf, "%lu\n", PAGES2KB(oom_freed_pages));
365 }
366
store_oom_pages(struct sys_device * dev,struct sysdev_attribute * attr,const char * buf,size_t count)367 static ssize_t store_oom_pages(struct sys_device *dev,
368 struct sysdev_attribute *attr,
369 const char *buf, size_t count)
370 {
371 unsigned long val = simple_strtoul (buf, NULL, 10);
372
373 if (!capable(CAP_SYS_ADMIN))
374 return -EPERM;
375 if (val != 0)
376 return -EBADMSG;
377
378 oom_freed_pages = 0;
379 return count;
380 }
381
382 static SYSDEV_ATTR(oom_freed_kb, S_IWUSR| S_IRUGO,
383 show_oom_pages, store_oom_pages);
384
385 static struct sysdev_attribute *cmm_attrs[] = {
386 &attr_loaned_kb,
387 &attr_loaned_target_kb,
388 &attr_oom_freed_kb,
389 };
390
391 static struct sysdev_class cmm_sysdev_class = {
392 .name = "cmm",
393 };
394
395 /**
396 * cmm_sysfs_register - Register with sysfs
397 *
398 * Return value:
399 * 0 on success / other on failure
400 **/
cmm_sysfs_register(struct sys_device * sysdev)401 static int cmm_sysfs_register(struct sys_device *sysdev)
402 {
403 int i, rc;
404
405 if ((rc = sysdev_class_register(&cmm_sysdev_class)))
406 return rc;
407
408 sysdev->id = 0;
409 sysdev->cls = &cmm_sysdev_class;
410
411 if ((rc = sysdev_register(sysdev)))
412 goto class_unregister;
413
414 for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++) {
415 if ((rc = sysdev_create_file(sysdev, cmm_attrs[i])))
416 goto fail;
417 }
418
419 return 0;
420
421 fail:
422 while (--i >= 0)
423 sysdev_remove_file(sysdev, cmm_attrs[i]);
424 sysdev_unregister(sysdev);
425 class_unregister:
426 sysdev_class_unregister(&cmm_sysdev_class);
427 return rc;
428 }
429
430 /**
431 * cmm_unregister_sysfs - Unregister from sysfs
432 *
433 **/
cmm_unregister_sysfs(struct sys_device * sysdev)434 static void cmm_unregister_sysfs(struct sys_device *sysdev)
435 {
436 int i;
437
438 for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++)
439 sysdev_remove_file(sysdev, cmm_attrs[i]);
440 sysdev_unregister(sysdev);
441 sysdev_class_unregister(&cmm_sysdev_class);
442 }
443
444 /**
445 * cmm_reboot_notifier - Make sure pages are not still marked as "loaned"
446 *
447 **/
cmm_reboot_notifier(struct notifier_block * nb,unsigned long action,void * unused)448 static int cmm_reboot_notifier(struct notifier_block *nb,
449 unsigned long action, void *unused)
450 {
451 if (action == SYS_RESTART) {
452 if (cmm_thread_ptr)
453 kthread_stop(cmm_thread_ptr);
454 cmm_thread_ptr = NULL;
455 cmm_free_pages(loaned_pages);
456 }
457 return NOTIFY_DONE;
458 }
459
460 static struct notifier_block cmm_reboot_nb = {
461 .notifier_call = cmm_reboot_notifier,
462 };
463
464 /**
465 * cmm_count_pages - Count the number of pages loaned in a particular range.
466 *
467 * @arg: memory_isolate_notify structure with address range and count
468 *
469 * Return value:
470 * 0 on success
471 **/
cmm_count_pages(void * arg)472 static unsigned long cmm_count_pages(void *arg)
473 {
474 struct memory_isolate_notify *marg = arg;
475 struct cmm_page_array *pa;
476 unsigned long start = (unsigned long)pfn_to_kaddr(marg->start_pfn);
477 unsigned long end = start + (marg->nr_pages << PAGE_SHIFT);
478 unsigned long idx;
479
480 spin_lock(&cmm_lock);
481 pa = cmm_page_list;
482 while (pa) {
483 if ((unsigned long)pa >= start && (unsigned long)pa < end)
484 marg->pages_found++;
485 for (idx = 0; idx < pa->index; idx++)
486 if (pa->page[idx] >= start && pa->page[idx] < end)
487 marg->pages_found++;
488 pa = pa->next;
489 }
490 spin_unlock(&cmm_lock);
491 return 0;
492 }
493
494 /**
495 * cmm_memory_isolate_cb - Handle memory isolation notifier calls
496 * @self: notifier block struct
497 * @action: action to take
498 * @arg: struct memory_isolate_notify data for handler
499 *
500 * Return value:
501 * NOTIFY_OK or notifier error based on subfunction return value
502 **/
cmm_memory_isolate_cb(struct notifier_block * self,unsigned long action,void * arg)503 static int cmm_memory_isolate_cb(struct notifier_block *self,
504 unsigned long action, void *arg)
505 {
506 int ret = 0;
507
508 if (action == MEM_ISOLATE_COUNT)
509 ret = cmm_count_pages(arg);
510
511 return notifier_from_errno(ret);
512 }
513
514 static struct notifier_block cmm_mem_isolate_nb = {
515 .notifier_call = cmm_memory_isolate_cb,
516 .priority = CMM_MEM_ISOLATE_PRI
517 };
518
519 /**
520 * cmm_mem_going_offline - Unloan pages where memory is to be removed
521 * @arg: memory_notify structure with page range to be offlined
522 *
523 * Return value:
524 * 0 on success
525 **/
cmm_mem_going_offline(void * arg)526 static int cmm_mem_going_offline(void *arg)
527 {
528 struct memory_notify *marg = arg;
529 unsigned long start_page = (unsigned long)pfn_to_kaddr(marg->start_pfn);
530 unsigned long end_page = start_page + (marg->nr_pages << PAGE_SHIFT);
531 struct cmm_page_array *pa_curr, *pa_last, *npa;
532 unsigned long idx;
533 unsigned long freed = 0;
534
535 cmm_dbg("Memory going offline, searching 0x%lx (%ld pages).\n",
536 start_page, marg->nr_pages);
537 spin_lock(&cmm_lock);
538
539 /* Search the page list for pages in the range to be offlined */
540 pa_last = pa_curr = cmm_page_list;
541 while (pa_curr) {
542 for (idx = (pa_curr->index - 1); (idx + 1) > 0; idx--) {
543 if ((pa_curr->page[idx] < start_page) ||
544 (pa_curr->page[idx] >= end_page))
545 continue;
546
547 plpar_page_set_active(__pa(pa_curr->page[idx]));
548 free_page(pa_curr->page[idx]);
549 freed++;
550 loaned_pages--;
551 totalram_pages++;
552 pa_curr->page[idx] = pa_last->page[--pa_last->index];
553 if (pa_last->index == 0) {
554 if (pa_curr == pa_last)
555 pa_curr = pa_last->next;
556 pa_last = pa_last->next;
557 free_page((unsigned long)cmm_page_list);
558 cmm_page_list = pa_last;
559 continue;
560 }
561 }
562 pa_curr = pa_curr->next;
563 }
564
565 /* Search for page list structures in the range to be offlined */
566 pa_last = NULL;
567 pa_curr = cmm_page_list;
568 while (pa_curr) {
569 if (((unsigned long)pa_curr >= start_page) &&
570 ((unsigned long)pa_curr < end_page)) {
571 npa = (struct cmm_page_array *)__get_free_page(
572 GFP_NOIO | __GFP_NOWARN |
573 __GFP_NORETRY | __GFP_NOMEMALLOC);
574 if (!npa) {
575 spin_unlock(&cmm_lock);
576 cmm_dbg("Failed to allocate memory for list "
577 "management. Memory hotplug "
578 "failed.\n");
579 return ENOMEM;
580 }
581 memcpy(npa, pa_curr, PAGE_SIZE);
582 if (pa_curr == cmm_page_list)
583 cmm_page_list = npa;
584 if (pa_last)
585 pa_last->next = npa;
586 free_page((unsigned long) pa_curr);
587 freed++;
588 pa_curr = npa;
589 }
590
591 pa_last = pa_curr;
592 pa_curr = pa_curr->next;
593 }
594
595 spin_unlock(&cmm_lock);
596 cmm_dbg("Released %ld pages in the search range.\n", freed);
597
598 return 0;
599 }
600
601 /**
602 * cmm_memory_cb - Handle memory hotplug notifier calls
603 * @self: notifier block struct
604 * @action: action to take
605 * @arg: struct memory_notify data for handler
606 *
607 * Return value:
608 * NOTIFY_OK or notifier error based on subfunction return value
609 *
610 **/
cmm_memory_cb(struct notifier_block * self,unsigned long action,void * arg)611 static int cmm_memory_cb(struct notifier_block *self,
612 unsigned long action, void *arg)
613 {
614 int ret = 0;
615
616 switch (action) {
617 case MEM_GOING_OFFLINE:
618 mutex_lock(&hotplug_mutex);
619 hotplug_occurred = 1;
620 ret = cmm_mem_going_offline(arg);
621 break;
622 case MEM_OFFLINE:
623 case MEM_CANCEL_OFFLINE:
624 mutex_unlock(&hotplug_mutex);
625 cmm_dbg("Memory offline operation complete.\n");
626 break;
627 case MEM_GOING_ONLINE:
628 case MEM_ONLINE:
629 case MEM_CANCEL_ONLINE:
630 break;
631 }
632
633 return notifier_from_errno(ret);
634 }
635
636 static struct notifier_block cmm_mem_nb = {
637 .notifier_call = cmm_memory_cb,
638 .priority = CMM_MEM_HOTPLUG_PRI
639 };
640
641 /**
642 * cmm_init - Module initialization
643 *
644 * Return value:
645 * 0 on success / other on failure
646 **/
cmm_init(void)647 static int cmm_init(void)
648 {
649 int rc = -ENOMEM;
650
651 if (!firmware_has_feature(FW_FEATURE_CMO))
652 return -EOPNOTSUPP;
653
654 if ((rc = register_oom_notifier(&cmm_oom_nb)) < 0)
655 return rc;
656
657 if ((rc = register_reboot_notifier(&cmm_reboot_nb)))
658 goto out_oom_notifier;
659
660 if ((rc = cmm_sysfs_register(&cmm_sysdev)))
661 goto out_reboot_notifier;
662
663 if (register_memory_notifier(&cmm_mem_nb) ||
664 register_memory_isolate_notifier(&cmm_mem_isolate_nb))
665 goto out_unregister_notifier;
666
667 if (cmm_disabled)
668 return rc;
669
670 cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
671 if (IS_ERR(cmm_thread_ptr)) {
672 rc = PTR_ERR(cmm_thread_ptr);
673 goto out_unregister_notifier;
674 }
675
676 return rc;
677
678 out_unregister_notifier:
679 unregister_memory_notifier(&cmm_mem_nb);
680 unregister_memory_isolate_notifier(&cmm_mem_isolate_nb);
681 cmm_unregister_sysfs(&cmm_sysdev);
682 out_reboot_notifier:
683 unregister_reboot_notifier(&cmm_reboot_nb);
684 out_oom_notifier:
685 unregister_oom_notifier(&cmm_oom_nb);
686 return rc;
687 }
688
689 /**
690 * cmm_exit - Module exit
691 *
692 * Return value:
693 * nothing
694 **/
cmm_exit(void)695 static void cmm_exit(void)
696 {
697 if (cmm_thread_ptr)
698 kthread_stop(cmm_thread_ptr);
699 unregister_oom_notifier(&cmm_oom_nb);
700 unregister_reboot_notifier(&cmm_reboot_nb);
701 unregister_memory_notifier(&cmm_mem_nb);
702 unregister_memory_isolate_notifier(&cmm_mem_isolate_nb);
703 cmm_free_pages(loaned_pages);
704 cmm_unregister_sysfs(&cmm_sysdev);
705 }
706
707 /**
708 * cmm_set_disable - Disable/Enable CMM
709 *
710 * Return value:
711 * 0 on success / other on failure
712 **/
cmm_set_disable(const char * val,struct kernel_param * kp)713 static int cmm_set_disable(const char *val, struct kernel_param *kp)
714 {
715 int disable = simple_strtoul(val, NULL, 10);
716
717 if (disable != 0 && disable != 1)
718 return -EINVAL;
719
720 if (disable && !cmm_disabled) {
721 if (cmm_thread_ptr)
722 kthread_stop(cmm_thread_ptr);
723 cmm_thread_ptr = NULL;
724 cmm_free_pages(loaned_pages);
725 } else if (!disable && cmm_disabled) {
726 cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
727 if (IS_ERR(cmm_thread_ptr))
728 return PTR_ERR(cmm_thread_ptr);
729 }
730
731 cmm_disabled = disable;
732 return 0;
733 }
734
735 module_param_call(disable, cmm_set_disable, param_get_uint,
736 &cmm_disabled, S_IRUGO | S_IWUSR);
737 MODULE_PARM_DESC(disable, "Disable CMM. Set to 1 to disable. "
738 "[Default=" __stringify(CMM_DISABLE) "]");
739
740 module_init(cmm_init);
741 module_exit(cmm_exit);
742