Pileus Git - ~andy/linux/blob - arch/powerpc/platforms/pseries/cmm.c

   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/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  * 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 device cmm_dev;
  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  **/
 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  **/
 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  **/
 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  **/
 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  **/
 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 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
 358 CMM_SHOW(loaned_kb, "%lu\n", PAGES2KB(loaned_pages));
 359 CMM_SHOW(loaned_target_kb, "%lu\n", PAGES2KB(loaned_pages_target));
 360
 361 static 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
 367 static 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
 382 static DEVICE_ATTR(oom_freed_kb, S_IWUSR | S_IRUGO,
 383                    show_oom_pages, store_oom_pages);
 384
 385 static struct device_attribute *cmm_attrs[] = {
 386         &dev_attr_loaned_kb,
 387         &dev_attr_loaned_target_kb,
 388         &dev_attr_oom_freed_kb,
 389 };
 390
 391 static struct bus_type cmm_subsys = {
 392         .name = "cmm",
 393         .dev_name = "cmm",
 394 };
 395
 396 /**
 397  * cmm_sysfs_register - Register with sysfs
 398  *
 399  * Return value:
 400  *      0 on success / other on failure
 401  **/
 402 static 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
 422 fail:
 423         while (--i >= 0)
 424                 device_remove_file(dev, cmm_attrs[i]);
 425         device_unregister(dev);
 426 subsys_unregister:
 427         bus_unregister(&cmm_subsys);
 428         return rc;
 429 }
 430
 431 /**
 432  * cmm_unregister_sysfs - Unregister from sysfs
 433  *
 434  **/
 435 static 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  * cmm_reboot_notifier - Make sure pages are not still marked as "loaned"
 447  *
 448  **/
 449 static 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
 461 static struct notifier_block cmm_reboot_nb = {
 462         .notifier_call = cmm_reboot_notifier,
 463 };
 464
 465 /**
 466  * cmm_count_pages - Count the number of pages loaned in a particular range.
 467  *
 468  * @arg: memory_isolate_notify structure with address range and count
 469  *
 470  * Return value:
 471  *      0 on success
 472  **/
 473 static 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  * cmm_memory_isolate_cb - Handle memory isolation notifier calls
 497  * @self:       notifier block struct
 498  * @action:     action to take
 499  * @arg:        struct memory_isolate_notify data for handler
 500  *
 501  * Return value:
 502  *      NOTIFY_OK or notifier error based on subfunction return value
 503  **/
 504 static 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
 515 static struct notifier_block cmm_mem_isolate_nb = {
 516         .notifier_call = cmm_memory_isolate_cb,
 517         .priority = CMM_MEM_ISOLATE_PRI
 518 };
 519
 520 /**
 521  * cmm_mem_going_offline - Unloan pages where memory is to be removed
 522  * @arg: memory_notify structure with page range to be offlined
 523  *
 524  * Return value:
 525  *      0 on success
 526  **/
 527 static 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         /* Search the page list for pages in the range to be offlined */
 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         /* Search for page list structures in the range to be offlined */
 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  * cmm_memory_cb - Handle memory hotplug notifier calls
 604  * @self:       notifier block struct
 605  * @action:     action to take
 606  * @arg:        struct memory_notify data for handler
 607  *
 608  * Return value:
 609  *      NOTIFY_OK or notifier error based on subfunction return value
 610  *
 611  **/
 612 static 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
 637 static struct notifier_block cmm_mem_nb = {
 638         .notifier_call = cmm_memory_cb,
 639         .priority = CMM_MEM_HOTPLUG_PRI
 640 };
 641
 642 /**
 643  * cmm_init - Module initialization
 644  *
 645  * Return value:
 646  *      0 on success / other on failure
 647  **/
 648 static 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
 679 out_unregister_notifier:
 680         unregister_memory_notifier(&cmm_mem_nb);
 681         unregister_memory_isolate_notifier(&cmm_mem_isolate_nb);
 682         cmm_unregister_sysfs(&cmm_dev);
 683 out_reboot_notifier:
 684         unregister_reboot_notifier(&cmm_reboot_nb);
 685 out_oom_notifier:
 686         unregister_oom_notifier(&cmm_oom_nb);
 687         return rc;
 688 }
 689
 690 /**
 691  * cmm_exit - Module exit
 692  *
 693  * Return value:
 694  *      nothing
 695  **/
 696 static 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  * cmm_set_disable - Disable/Enable CMM
 710  *
 711  * Return value:
 712  *      0 on success / other on failure
 713  **/
 714 static 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
 736 module_param_call(disable, cmm_set_disable, param_get_uint,
 737                   &cmm_disabled, S_IRUGO | S_IWUSR);
 738 MODULE_PARM_DESC(disable, "Disable CMM. Set to 1 to disable. "
 739                  "[Default=" __stringify(CMM_DISABLE) "]");
 740
 741 module_init(cmm_init);
 742 module_exit(cmm_exit);