2 * Collaborative memory management interface.
4 * Copyright (C) 2008 IBM Corporation
5 * Author(s): Brian King (brking@linux.vnet.ibm.com),
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.
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.
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
23 #include <linux/ctype.h>
24 #include <linux/delay.h>
25 #include <linux/errno.h>
27 #include <linux/gfp.h>
28 #include <linux/kthread.h>
29 #include <linux/module.h>
30 #include <linux/oom.h>
31 #include <linux/reboot.h>
32 #include <linux/sched.h>
33 #include <linux/stringify.h>
34 #include <linux/swap.h>
35 #include <linux/device.h>
36 #include <asm/firmware.h>
37 #include <asm/hvcall.h>
39 #include <asm/pgalloc.h>
40 #include <linux/uaccess.h>
41 #include <linux/memory.h>
42 #include <asm/plpar_wrappers.h>
46 #define CMM_DRIVER_VERSION "1.0.0"
47 #define CMM_DEFAULT_DELAY 1
48 #define CMM_HOTPLUG_DELAY 5
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))
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.
59 #define CMM_MEM_HOTPLUG_PRI 1
60 #define CMM_MEM_ISOLATE_PRI 15
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 device cmm_dev;
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);
75 module_param_named(delay, delay, uint, 0644);
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, 0644);
79 MODULE_PARM_DESC(hotplug_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, 0644);
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, 0644);
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, 0644);
89 MODULE_PARM_DESC(debug, "Enable module debugging logging. Set to 1 to enable. "
90 "[Default=" __stringify(CMM_DEBUG) "]");
92 #define CMM_NR_PAGES ((PAGE_SIZE - sizeof(void *) - sizeof(unsigned long)) / sizeof(unsigned long))
94 #define cmm_dbg(...) if (cmm_debug) { printk(KERN_INFO "cmm: "__VA_ARGS__); }
96 struct cmm_page_array {
97 struct cmm_page_array *next;
99 unsigned long page[CMM_NR_PAGES];
102 static unsigned long loaned_pages;
103 static unsigned long loaned_pages_target;
104 static unsigned long oom_freed_pages;
106 static struct cmm_page_array *cmm_page_list;
107 static DEFINE_SPINLOCK(cmm_lock);
109 static DEFINE_MUTEX(hotplug_mutex);
110 static int hotplug_occurred; /* protected by the hotplug mutex */
112 static struct task_struct *cmm_thread_ptr;
114 static long plpar_page_set_loaned(unsigned long vpa)
116 unsigned long cmo_page_sz = cmo_get_page_size();
120 for (i = 0; !rc && i < PAGE_SIZE; i += cmo_page_sz)
121 rc = plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_LOANED, vpa + i, 0);
123 for (i -= cmo_page_sz; rc && i != 0; i -= cmo_page_sz)
124 plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_ACTIVE,
125 vpa + i - cmo_page_sz, 0);
130 static long plpar_page_set_active(unsigned long vpa)
132 unsigned long cmo_page_sz = cmo_get_page_size();
136 for (i = 0; !rc && i < PAGE_SIZE; i += cmo_page_sz)
137 rc = plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_ACTIVE, vpa + i, 0);
139 for (i -= cmo_page_sz; rc && i != 0; i -= cmo_page_sz)
140 plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_LOANED,
141 vpa + i - cmo_page_sz, 0);
147 * cmm_alloc_pages - Allocate pages and mark them as loaned
148 * @nr: number of pages to allocate
151 * number of pages requested to be allocated which were not
153 static long cmm_alloc_pages(long nr)
155 struct cmm_page_array *pa, *npa;
159 cmm_dbg("Begin request for %ld pages\n", nr);
162 /* Exit if a hotplug operation is in progress or occurred */
163 if (mutex_trylock(&hotplug_mutex)) {
164 if (hotplug_occurred) {
165 mutex_unlock(&hotplug_mutex);
168 mutex_unlock(&hotplug_mutex);
173 addr = __get_free_page(GFP_NOIO | __GFP_NOWARN |
174 __GFP_NORETRY | __GFP_NOMEMALLOC);
177 spin_lock(&cmm_lock);
179 if (!pa || pa->index >= CMM_NR_PAGES) {
180 /* Need a new page for the page list. */
181 spin_unlock(&cmm_lock);
182 npa = (struct cmm_page_array *)__get_free_page(
183 GFP_NOIO | __GFP_NOWARN |
184 __GFP_NORETRY | __GFP_NOMEMALLOC);
186 pr_info("%s: Can not allocate new page list\n", __func__);
190 spin_lock(&cmm_lock);
193 if (!pa || pa->index >= CMM_NR_PAGES) {
199 free_page((unsigned long) npa);
202 if ((rc = plpar_page_set_loaned(__pa(addr)))) {
203 pr_err("%s: Can not set page to loaned. rc=%ld\n", __func__, rc);
204 spin_unlock(&cmm_lock);
209 pa->page[pa->index++] = addr;
212 spin_unlock(&cmm_lock);
216 cmm_dbg("End request with %ld pages unfulfilled\n", nr);
221 * cmm_free_pages - Free pages and mark them as active
222 * @nr: number of pages to free
225 * number of pages requested to be freed which were not
227 static long cmm_free_pages(long nr)
229 struct cmm_page_array *pa;
232 cmm_dbg("Begin free of %ld pages.\n", nr);
233 spin_lock(&cmm_lock);
236 if (!pa || pa->index <= 0)
238 addr = pa->page[--pa->index];
240 if (pa->index == 0) {
242 free_page((unsigned long) cmm_page_list);
246 plpar_page_set_active(__pa(addr));
252 spin_unlock(&cmm_lock);
253 cmm_dbg("End request with %ld pages unfulfilled\n", nr);
258 * cmm_oom_notify - OOM notifier
259 * @self: notifier block struct
261 * @parm: returned - number of pages freed
266 static int cmm_oom_notify(struct notifier_block *self,
267 unsigned long dummy, void *parm)
269 unsigned long *freed = parm;
270 long nr = KB2PAGES(oom_kb);
272 cmm_dbg("OOM processing started\n");
273 nr = cmm_free_pages(nr);
274 loaned_pages_target = loaned_pages;
275 *freed += KB2PAGES(oom_kb) - nr;
276 oom_freed_pages += KB2PAGES(oom_kb) - nr;
277 cmm_dbg("OOM processing complete\n");
282 * cmm_get_mpp - Read memory performance parameters
284 * Makes hcall to query the current page loan request from the hypervisor.
289 static void cmm_get_mpp(void)
292 struct hvcall_mpp_data mpp_data;
293 signed long active_pages_target, page_loan_request, target;
294 signed long total_pages = totalram_pages + loaned_pages;
295 signed long min_mem_pages = (min_mem_mb * 1024 * 1024) / PAGE_SIZE;
297 rc = h_get_mpp(&mpp_data);
302 page_loan_request = div_s64((s64)mpp_data.loan_request, PAGE_SIZE);
303 target = page_loan_request + (signed long)loaned_pages;
305 if (target < 0 || total_pages < min_mem_pages)
308 if (target > oom_freed_pages)
309 target -= oom_freed_pages;
313 active_pages_target = total_pages - target;
315 if (min_mem_pages > active_pages_target)
316 target = total_pages - min_mem_pages;
321 loaned_pages_target = target;
323 cmm_dbg("delta = %ld, loaned = %lu, target = %lu, oom = %lu, totalram = %lu\n",
324 page_loan_request, loaned_pages, loaned_pages_target,
325 oom_freed_pages, totalram_pages);
328 static struct notifier_block cmm_oom_nb = {
329 .notifier_call = cmm_oom_notify
333 * cmm_thread - CMM task thread
339 static int cmm_thread(void *dummy)
341 unsigned long timeleft;
344 timeleft = msleep_interruptible(delay * 1000);
346 if (kthread_should_stop() || timeleft)
349 if (mutex_trylock(&hotplug_mutex)) {
350 if (hotplug_occurred) {
351 hotplug_occurred = 0;
352 mutex_unlock(&hotplug_mutex);
353 cmm_dbg("Hotplug operation has occurred, "
354 "loaning activity suspended "
357 timeleft = msleep_interruptible(hotplug_delay *
359 if (kthread_should_stop() || timeleft)
363 mutex_unlock(&hotplug_mutex);
365 cmm_dbg("Hotplug operation in progress, activity "
372 if (loaned_pages_target > loaned_pages) {
373 if (cmm_alloc_pages(loaned_pages_target - loaned_pages))
374 loaned_pages_target = loaned_pages;
375 } else if (loaned_pages_target < loaned_pages)
376 cmm_free_pages(loaned_pages - loaned_pages_target);
381 #define CMM_SHOW(name, format, args...) \
382 static ssize_t show_##name(struct device *dev, \
383 struct device_attribute *attr, \
386 return sprintf(buf, format, ##args); \
388 static DEVICE_ATTR(name, 0444, show_##name, NULL)
390 CMM_SHOW(loaned_kb, "%lu\n", PAGES2KB(loaned_pages));
391 CMM_SHOW(loaned_target_kb, "%lu\n", PAGES2KB(loaned_pages_target));
393 static ssize_t show_oom_pages(struct device *dev,
394 struct device_attribute *attr, char *buf)
396 return sprintf(buf, "%lu\n", PAGES2KB(oom_freed_pages));
399 static ssize_t store_oom_pages(struct device *dev,
400 struct device_attribute *attr,
401 const char *buf, size_t count)
403 unsigned long val = simple_strtoul (buf, NULL, 10);
405 if (!capable(CAP_SYS_ADMIN))
414 static DEVICE_ATTR(oom_freed_kb, 0644,
415 show_oom_pages, store_oom_pages);
417 static struct device_attribute *cmm_attrs[] = {
419 &dev_attr_loaned_target_kb,
420 &dev_attr_oom_freed_kb,
423 static struct bus_type cmm_subsys = {
428 static void cmm_release_device(struct device *dev)
433 * cmm_sysfs_register - Register with sysfs
436 * 0 on success / other on failure
438 static int cmm_sysfs_register(struct device *dev)
442 if ((rc = subsys_system_register(&cmm_subsys, NULL)))
446 dev->bus = &cmm_subsys;
447 dev->release = cmm_release_device;
449 if ((rc = device_register(dev)))
450 goto subsys_unregister;
452 for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++) {
453 if ((rc = device_create_file(dev, cmm_attrs[i])))
461 device_remove_file(dev, cmm_attrs[i]);
462 device_unregister(dev);
464 bus_unregister(&cmm_subsys);
469 * cmm_unregister_sysfs - Unregister from sysfs
472 static void cmm_unregister_sysfs(struct device *dev)
476 for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++)
477 device_remove_file(dev, cmm_attrs[i]);
478 device_unregister(dev);
479 bus_unregister(&cmm_subsys);
483 * cmm_reboot_notifier - Make sure pages are not still marked as "loaned"
486 static int cmm_reboot_notifier(struct notifier_block *nb,
487 unsigned long action, void *unused)
489 if (action == SYS_RESTART) {
491 kthread_stop(cmm_thread_ptr);
492 cmm_thread_ptr = NULL;
493 cmm_free_pages(loaned_pages);
498 static struct notifier_block cmm_reboot_nb = {
499 .notifier_call = cmm_reboot_notifier,
503 * cmm_count_pages - Count the number of pages loaned in a particular range.
505 * @arg: memory_isolate_notify structure with address range and count
510 static unsigned long cmm_count_pages(void *arg)
512 struct memory_isolate_notify *marg = arg;
513 struct cmm_page_array *pa;
514 unsigned long start = (unsigned long)pfn_to_kaddr(marg->start_pfn);
515 unsigned long end = start + (marg->nr_pages << PAGE_SHIFT);
518 spin_lock(&cmm_lock);
521 if ((unsigned long)pa >= start && (unsigned long)pa < end)
523 for (idx = 0; idx < pa->index; idx++)
524 if (pa->page[idx] >= start && pa->page[idx] < end)
528 spin_unlock(&cmm_lock);
533 * cmm_memory_isolate_cb - Handle memory isolation notifier calls
534 * @self: notifier block struct
535 * @action: action to take
536 * @arg: struct memory_isolate_notify data for handler
539 * NOTIFY_OK or notifier error based on subfunction return value
541 static int cmm_memory_isolate_cb(struct notifier_block *self,
542 unsigned long action, void *arg)
546 if (action == MEM_ISOLATE_COUNT)
547 ret = cmm_count_pages(arg);
549 return notifier_from_errno(ret);
552 static struct notifier_block cmm_mem_isolate_nb = {
553 .notifier_call = cmm_memory_isolate_cb,
554 .priority = CMM_MEM_ISOLATE_PRI
558 * cmm_mem_going_offline - Unloan pages where memory is to be removed
559 * @arg: memory_notify structure with page range to be offlined
564 static int cmm_mem_going_offline(void *arg)
566 struct memory_notify *marg = arg;
567 unsigned long start_page = (unsigned long)pfn_to_kaddr(marg->start_pfn);
568 unsigned long end_page = start_page + (marg->nr_pages << PAGE_SHIFT);
569 struct cmm_page_array *pa_curr, *pa_last, *npa;
571 unsigned long freed = 0;
573 cmm_dbg("Memory going offline, searching 0x%lx (%ld pages).\n",
574 start_page, marg->nr_pages);
575 spin_lock(&cmm_lock);
577 /* Search the page list for pages in the range to be offlined */
578 pa_last = pa_curr = cmm_page_list;
580 for (idx = (pa_curr->index - 1); (idx + 1) > 0; idx--) {
581 if ((pa_curr->page[idx] < start_page) ||
582 (pa_curr->page[idx] >= end_page))
585 plpar_page_set_active(__pa(pa_curr->page[idx]));
586 free_page(pa_curr->page[idx]);
590 pa_curr->page[idx] = pa_last->page[--pa_last->index];
591 if (pa_last->index == 0) {
592 if (pa_curr == pa_last)
593 pa_curr = pa_last->next;
594 pa_last = pa_last->next;
595 free_page((unsigned long)cmm_page_list);
596 cmm_page_list = pa_last;
599 pa_curr = pa_curr->next;
602 /* Search for page list structures in the range to be offlined */
604 pa_curr = cmm_page_list;
606 if (((unsigned long)pa_curr >= start_page) &&
607 ((unsigned long)pa_curr < end_page)) {
608 npa = (struct cmm_page_array *)__get_free_page(
609 GFP_NOIO | __GFP_NOWARN |
610 __GFP_NORETRY | __GFP_NOMEMALLOC);
612 spin_unlock(&cmm_lock);
613 cmm_dbg("Failed to allocate memory for list "
614 "management. Memory hotplug "
618 memcpy(npa, pa_curr, PAGE_SIZE);
619 if (pa_curr == cmm_page_list)
623 free_page((unsigned long) pa_curr);
629 pa_curr = pa_curr->next;
632 spin_unlock(&cmm_lock);
633 cmm_dbg("Released %ld pages in the search range.\n", freed);
639 * cmm_memory_cb - Handle memory hotplug notifier calls
640 * @self: notifier block struct
641 * @action: action to take
642 * @arg: struct memory_notify data for handler
645 * NOTIFY_OK or notifier error based on subfunction return value
648 static int cmm_memory_cb(struct notifier_block *self,
649 unsigned long action, void *arg)
654 case MEM_GOING_OFFLINE:
655 mutex_lock(&hotplug_mutex);
656 hotplug_occurred = 1;
657 ret = cmm_mem_going_offline(arg);
660 case MEM_CANCEL_OFFLINE:
661 mutex_unlock(&hotplug_mutex);
662 cmm_dbg("Memory offline operation complete.\n");
664 case MEM_GOING_ONLINE:
666 case MEM_CANCEL_ONLINE:
670 return notifier_from_errno(ret);
673 static struct notifier_block cmm_mem_nb = {
674 .notifier_call = cmm_memory_cb,
675 .priority = CMM_MEM_HOTPLUG_PRI
679 * cmm_init - Module initialization
682 * 0 on success / other on failure
684 static int cmm_init(void)
688 if (!firmware_has_feature(FW_FEATURE_CMO))
691 if ((rc = register_oom_notifier(&cmm_oom_nb)) < 0)
694 if ((rc = register_reboot_notifier(&cmm_reboot_nb)))
695 goto out_oom_notifier;
697 if ((rc = cmm_sysfs_register(&cmm_dev)))
698 goto out_reboot_notifier;
700 if (register_memory_notifier(&cmm_mem_nb) ||
701 register_memory_isolate_notifier(&cmm_mem_isolate_nb))
702 goto out_unregister_notifier;
707 cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
708 if (IS_ERR(cmm_thread_ptr)) {
709 rc = PTR_ERR(cmm_thread_ptr);
710 goto out_unregister_notifier;
715 out_unregister_notifier:
716 unregister_memory_notifier(&cmm_mem_nb);
717 unregister_memory_isolate_notifier(&cmm_mem_isolate_nb);
718 cmm_unregister_sysfs(&cmm_dev);
720 unregister_reboot_notifier(&cmm_reboot_nb);
722 unregister_oom_notifier(&cmm_oom_nb);
727 * cmm_exit - Module exit
732 static void cmm_exit(void)
735 kthread_stop(cmm_thread_ptr);
736 unregister_oom_notifier(&cmm_oom_nb);
737 unregister_reboot_notifier(&cmm_reboot_nb);
738 unregister_memory_notifier(&cmm_mem_nb);
739 unregister_memory_isolate_notifier(&cmm_mem_isolate_nb);
740 cmm_free_pages(loaned_pages);
741 cmm_unregister_sysfs(&cmm_dev);
745 * cmm_set_disable - Disable/Enable CMM
748 * 0 on success / other on failure
750 static int cmm_set_disable(const char *val, const struct kernel_param *kp)
752 int disable = simple_strtoul(val, NULL, 10);
754 if (disable != 0 && disable != 1)
757 if (disable && !cmm_disabled) {
759 kthread_stop(cmm_thread_ptr);
760 cmm_thread_ptr = NULL;
761 cmm_free_pages(loaned_pages);
762 } else if (!disable && cmm_disabled) {
763 cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
764 if (IS_ERR(cmm_thread_ptr))
765 return PTR_ERR(cmm_thread_ptr);
768 cmm_disabled = disable;
772 module_param_call(disable, cmm_set_disable, param_get_uint,
773 &cmm_disabled, 0644);
774 MODULE_PARM_DESC(disable, "Disable CMM. Set to 1 to disable. "
775 "[Default=" __stringify(CMM_DISABLE) "]");
777 module_init(cmm_init);
778 module_exit(cmm_exit);