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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/device.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
57
58
59#define CMM_MEM_HOTPLUG_PRI 1
60#define CMM_MEM_ISOLATE_PRI 15
61
62static unsigned int delay = CMM_DEFAULT_DELAY;
63static unsigned int hotplug_delay = CMM_HOTPLUG_DELAY;
64static unsigned int oom_kb = CMM_OOM_KB;
65static unsigned int cmm_debug = CMM_DEBUG;
66static unsigned int cmm_disabled = CMM_DISABLE;
67static unsigned long min_mem_mb = CMM_MIN_MEM_MB;
68static struct device cmm_dev;
69
70MODULE_AUTHOR("Brian King <brking@linux.vnet.ibm.com>");
71MODULE_DESCRIPTION("IBM System p Collaborative Memory Manager");
72MODULE_LICENSE("GPL");
73MODULE_VERSION(CMM_DRIVER_VERSION);
74
75module_param_named(delay, delay, uint, S_IRUGO | S_IWUSR);
76MODULE_PARM_DESC(delay, "Delay (in seconds) between polls to query hypervisor paging requests. "
77 "[Default=" __stringify(CMM_DEFAULT_DELAY) "]");
78module_param_named(hotplug_delay, hotplug_delay, uint, S_IRUGO | S_IWUSR);
79MODULE_PARM_DESC(delay, "Delay (in seconds) after memory hotplug remove "
80 "before loaning resumes. "
81 "[Default=" __stringify(CMM_HOTPLUG_DELAY) "]");
82module_param_named(oom_kb, oom_kb, uint, S_IRUGO | S_IWUSR);
83MODULE_PARM_DESC(oom_kb, "Amount of memory in kb to free on OOM. "
84 "[Default=" __stringify(CMM_OOM_KB) "]");
85module_param_named(min_mem_mb, min_mem_mb, ulong, S_IRUGO | S_IWUSR);
86MODULE_PARM_DESC(min_mem_mb, "Minimum amount of memory (in MB) to not balloon. "
87 "[Default=" __stringify(CMM_MIN_MEM_MB) "]");
88module_param_named(debug, cmm_debug, uint, S_IRUGO | S_IWUSR);
89MODULE_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
96struct cmm_page_array {
97 struct cmm_page_array *next;
98 unsigned long index;
99 unsigned long page[CMM_NR_PAGES];
100};
101
102static unsigned long loaned_pages;
103static unsigned long loaned_pages_target;
104static unsigned long oom_freed_pages;
105
106static struct cmm_page_array *cmm_page_list;
107static DEFINE_SPINLOCK(cmm_lock);
108
109static DEFINE_MUTEX(hotplug_mutex);
110static int hotplug_occurred;
111
112static struct task_struct *cmm_thread_ptr;
113
114
115
116
117
118
119
120
121static 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
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
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
190
191
192
193
194
195static 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
227
228
229
230
231
232
233
234static 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
251
252
253
254
255
256
257static 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
296static struct notifier_block cmm_oom_nb = {
297 .notifier_call = cmm_oom_notify
298};
299
300
301
302
303
304
305
306
307static 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 device *dev, \
351 struct device_attribute *attr, \
352 char *buf) \
353 { \
354 return sprintf(buf, format, ##args); \
355 } \
356 static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
357
358CMM_SHOW(loaned_kb, "%lu\n", PAGES2KB(loaned_pages));
359CMM_SHOW(loaned_target_kb, "%lu\n", PAGES2KB(loaned_pages_target));
360
361static ssize_t show_oom_pages(struct device *dev,
362 struct device_attribute *attr, char *buf)
363{
364 return sprintf(buf, "%lu\n", PAGES2KB(oom_freed_pages));
365}
366
367static ssize_t store_oom_pages(struct device *dev,
368 struct device_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
382static DEVICE_ATTR(oom_freed_kb, S_IWUSR | S_IRUGO,
383 show_oom_pages, store_oom_pages);
384
385static struct device_attribute *cmm_attrs[] = {
386 &dev_attr_loaned_kb,
387 &dev_attr_loaned_target_kb,
388 &dev_attr_oom_freed_kb,
389};
390
391static struct bus_type cmm_subsys = {
392 .name = "cmm",
393 .dev_name = "cmm",
394};
395
396
397
398
399
400
401
402static int cmm_sysfs_register(struct device *dev)
403{
404 int i, rc;
405
406 if ((rc = subsys_system_register(&cmm_subsys, NULL)))
407 return rc;
408
409 dev->id = 0;
410 dev->bus = &cmm_subsys;
411
412 if ((rc = device_register(dev)))
413 goto subsys_unregister;
414
415 for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++) {
416 if ((rc = device_create_file(dev, cmm_attrs[i])))
417 goto fail;
418 }
419
420 return 0;
421
422fail:
423 while (--i >= 0)
424 device_remove_file(dev, cmm_attrs[i]);
425 device_unregister(dev);
426subsys_unregister:
427 bus_unregister(&cmm_subsys);
428 return rc;
429}
430
431
432
433
434
435static void cmm_unregister_sysfs(struct device *dev)
436{
437 int i;
438
439 for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++)
440 device_remove_file(dev, cmm_attrs[i]);
441 device_unregister(dev);
442 bus_unregister(&cmm_subsys);
443}
444
445
446
447
448
449static int cmm_reboot_notifier(struct notifier_block *nb,
450 unsigned long action, void *unused)
451{
452 if (action == SYS_RESTART) {
453 if (cmm_thread_ptr)
454 kthread_stop(cmm_thread_ptr);
455 cmm_thread_ptr = NULL;
456 cmm_free_pages(loaned_pages);
457 }
458 return NOTIFY_DONE;
459}
460
461static struct notifier_block cmm_reboot_nb = {
462 .notifier_call = cmm_reboot_notifier,
463};
464
465
466
467
468
469
470
471
472
473static unsigned long cmm_count_pages(void *arg)
474{
475 struct memory_isolate_notify *marg = arg;
476 struct cmm_page_array *pa;
477 unsigned long start = (unsigned long)pfn_to_kaddr(marg->start_pfn);
478 unsigned long end = start + (marg->nr_pages << PAGE_SHIFT);
479 unsigned long idx;
480
481 spin_lock(&cmm_lock);
482 pa = cmm_page_list;
483 while (pa) {
484 if ((unsigned long)pa >= start && (unsigned long)pa < end)
485 marg->pages_found++;
486 for (idx = 0; idx < pa->index; idx++)
487 if (pa->page[idx] >= start && pa->page[idx] < end)
488 marg->pages_found++;
489 pa = pa->next;
490 }
491 spin_unlock(&cmm_lock);
492 return 0;
493}
494
495
496
497
498
499
500
501
502
503
504static int cmm_memory_isolate_cb(struct notifier_block *self,
505 unsigned long action, void *arg)
506{
507 int ret = 0;
508
509 if (action == MEM_ISOLATE_COUNT)
510 ret = cmm_count_pages(arg);
511
512 return notifier_from_errno(ret);
513}
514
515static struct notifier_block cmm_mem_isolate_nb = {
516 .notifier_call = cmm_memory_isolate_cb,
517 .priority = CMM_MEM_ISOLATE_PRI
518};
519
520
521
522
523
524
525
526
527static int cmm_mem_going_offline(void *arg)
528{
529 struct memory_notify *marg = arg;
530 unsigned long start_page = (unsigned long)pfn_to_kaddr(marg->start_pfn);
531 unsigned long end_page = start_page + (marg->nr_pages << PAGE_SHIFT);
532 struct cmm_page_array *pa_curr, *pa_last, *npa;
533 unsigned long idx;
534 unsigned long freed = 0;
535
536 cmm_dbg("Memory going offline, searching 0x%lx (%ld pages).\n",
537 start_page, marg->nr_pages);
538 spin_lock(&cmm_lock);
539
540
541 pa_last = pa_curr = cmm_page_list;
542 while (pa_curr) {
543 for (idx = (pa_curr->index - 1); (idx + 1) > 0; idx--) {
544 if ((pa_curr->page[idx] < start_page) ||
545 (pa_curr->page[idx] >= end_page))
546 continue;
547
548 plpar_page_set_active(__pa(pa_curr->page[idx]));
549 free_page(pa_curr->page[idx]);
550 freed++;
551 loaned_pages--;
552 totalram_pages++;
553 pa_curr->page[idx] = pa_last->page[--pa_last->index];
554 if (pa_last->index == 0) {
555 if (pa_curr == pa_last)
556 pa_curr = pa_last->next;
557 pa_last = pa_last->next;
558 free_page((unsigned long)cmm_page_list);
559 cmm_page_list = pa_last;
560 continue;
561 }
562 }
563 pa_curr = pa_curr->next;
564 }
565
566
567 pa_last = NULL;
568 pa_curr = cmm_page_list;
569 while (pa_curr) {
570 if (((unsigned long)pa_curr >= start_page) &&
571 ((unsigned long)pa_curr < end_page)) {
572 npa = (struct cmm_page_array *)__get_free_page(
573 GFP_NOIO | __GFP_NOWARN |
574 __GFP_NORETRY | __GFP_NOMEMALLOC);
575 if (!npa) {
576 spin_unlock(&cmm_lock);
577 cmm_dbg("Failed to allocate memory for list "
578 "management. Memory hotplug "
579 "failed.\n");
580 return ENOMEM;
581 }
582 memcpy(npa, pa_curr, PAGE_SIZE);
583 if (pa_curr == cmm_page_list)
584 cmm_page_list = npa;
585 if (pa_last)
586 pa_last->next = npa;
587 free_page((unsigned long) pa_curr);
588 freed++;
589 pa_curr = npa;
590 }
591
592 pa_last = pa_curr;
593 pa_curr = pa_curr->next;
594 }
595
596 spin_unlock(&cmm_lock);
597 cmm_dbg("Released %ld pages in the search range.\n", freed);
598
599 return 0;
600}
601
602
603
604
605
606
607
608
609
610
611
612static int cmm_memory_cb(struct notifier_block *self,
613 unsigned long action, void *arg)
614{
615 int ret = 0;
616
617 switch (action) {
618 case MEM_GOING_OFFLINE:
619 mutex_lock(&hotplug_mutex);
620 hotplug_occurred = 1;
621 ret = cmm_mem_going_offline(arg);
622 break;
623 case MEM_OFFLINE:
624 case MEM_CANCEL_OFFLINE:
625 mutex_unlock(&hotplug_mutex);
626 cmm_dbg("Memory offline operation complete.\n");
627 break;
628 case MEM_GOING_ONLINE:
629 case MEM_ONLINE:
630 case MEM_CANCEL_ONLINE:
631 break;
632 }
633
634 return notifier_from_errno(ret);
635}
636
637static struct notifier_block cmm_mem_nb = {
638 .notifier_call = cmm_memory_cb,
639 .priority = CMM_MEM_HOTPLUG_PRI
640};
641
642
643
644
645
646
647
648static int cmm_init(void)
649{
650 int rc = -ENOMEM;
651
652 if (!firmware_has_feature(FW_FEATURE_CMO))
653 return -EOPNOTSUPP;
654
655 if ((rc = register_oom_notifier(&cmm_oom_nb)) < 0)
656 return rc;
657
658 if ((rc = register_reboot_notifier(&cmm_reboot_nb)))
659 goto out_oom_notifier;
660
661 if ((rc = cmm_sysfs_register(&cmm_dev)))
662 goto out_reboot_notifier;
663
664 if (register_memory_notifier(&cmm_mem_nb) ||
665 register_memory_isolate_notifier(&cmm_mem_isolate_nb))
666 goto out_unregister_notifier;
667
668 if (cmm_disabled)
669 return rc;
670
671 cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
672 if (IS_ERR(cmm_thread_ptr)) {
673 rc = PTR_ERR(cmm_thread_ptr);
674 goto out_unregister_notifier;
675 }
676
677 return rc;
678
679out_unregister_notifier:
680 unregister_memory_notifier(&cmm_mem_nb);
681 unregister_memory_isolate_notifier(&cmm_mem_isolate_nb);
682 cmm_unregister_sysfs(&cmm_dev);
683out_reboot_notifier:
684 unregister_reboot_notifier(&cmm_reboot_nb);
685out_oom_notifier:
686 unregister_oom_notifier(&cmm_oom_nb);
687 return rc;
688}
689
690
691
692
693
694
695
696static void cmm_exit(void)
697{
698 if (cmm_thread_ptr)
699 kthread_stop(cmm_thread_ptr);
700 unregister_oom_notifier(&cmm_oom_nb);
701 unregister_reboot_notifier(&cmm_reboot_nb);
702 unregister_memory_notifier(&cmm_mem_nb);
703 unregister_memory_isolate_notifier(&cmm_mem_isolate_nb);
704 cmm_free_pages(loaned_pages);
705 cmm_unregister_sysfs(&cmm_dev);
706}
707
708
709
710
711
712
713
714static int cmm_set_disable(const char *val, struct kernel_param *kp)
715{
716 int disable = simple_strtoul(val, NULL, 10);
717
718 if (disable != 0 && disable != 1)
719 return -EINVAL;
720
721 if (disable && !cmm_disabled) {
722 if (cmm_thread_ptr)
723 kthread_stop(cmm_thread_ptr);
724 cmm_thread_ptr = NULL;
725 cmm_free_pages(loaned_pages);
726 } else if (!disable && cmm_disabled) {
727 cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
728 if (IS_ERR(cmm_thread_ptr))
729 return PTR_ERR(cmm_thread_ptr);
730 }
731
732 cmm_disabled = disable;
733 return 0;
734}
735
736module_param_call(disable, cmm_set_disable, param_get_uint,
737 &cmm_disabled, S_IRUGO | S_IWUSR);
738MODULE_PARM_DESC(disable, "Disable CMM. Set to 1 to disable. "
739 "[Default=" __stringify(CMM_DISABLE) "]");
740
741module_init(cmm_init);
742module_exit(cmm_exit);
743