arch/powerpc/platforms/pseries/cmm.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Collaborative memory management interface.
   4  *
   5  * Copyright (C) 2008 IBM Corporation
   6  * Author(s): Brian King (brking@linux.vnet.ibm.com),
   7  */
   8
   9 #include <linux/ctype.h>
  10 #include <linux/delay.h>
  11 #include <linux/errno.h>
  12 #include <linux/fs.h>
  13 #include <linux/gfp.h>
  14 #include <linux/kthread.h>
  15 #include <linux/module.h>
  16 #include <linux/oom.h>
  17 #include <linux/reboot.h>
  18 #include <linux/sched.h>
  19 #include <linux/stringify.h>
  20 #include <linux/swap.h>
  21 #include <linux/device.h>
  22 #include <asm/firmware.h>
  23 #include <asm/hvcall.h>
  24 #include <asm/mmu.h>
  25 #include <asm/pgalloc.h>
  26 #include <linux/uaccess.h>
  27 #include <linux/memory.h>
  28 #include <asm/plpar_wrappers.h>
  29
  30 #include "pseries.h"
  31
  32 #define CMM_DRIVER_VERSION      "1.0.0"
  33 #define CMM_DEFAULT_DELAY       1
  34 #define CMM_HOTPLUG_DELAY       5
  35 #define CMM_DEBUG                       0
  36 #define CMM_DISABLE             0
  37 #define CMM_OOM_KB              1024
  38 #define CMM_MIN_MEM_MB          256
  39 #define KB2PAGES(_p)            ((_p)>>(PAGE_SHIFT-10))
  40 #define PAGES2KB(_p)            ((_p)<<(PAGE_SHIFT-10))
  41 /*
  42  * The priority level tries to ensure that this notifier is called as
  43  * late as possible to reduce thrashing in the shared memory pool.
  44  */
  45 #define CMM_MEM_HOTPLUG_PRI     1
  46 #define CMM_MEM_ISOLATE_PRI     15
  47
  48 static unsigned int delay = CMM_DEFAULT_DELAY;
  49 static unsigned int hotplug_delay = CMM_HOTPLUG_DELAY;
  50 static unsigned int oom_kb = CMM_OOM_KB;
  51 static unsigned int cmm_debug = CMM_DEBUG;
  52 static unsigned int cmm_disabled = CMM_DISABLE;
  53 static unsigned long min_mem_mb = CMM_MIN_MEM_MB;
  54 static struct device cmm_dev;
  55
  56 MODULE_AUTHOR("Brian King <brking@linux.vnet.ibm.com>");
  57 MODULE_DESCRIPTION("IBM System p Collaborative Memory Manager");
  58 MODULE_LICENSE("GPL");
  59 MODULE_VERSION(CMM_DRIVER_VERSION);
  60
  61 module_param_named(delay, delay, uint, 0644);
  62 MODULE_PARM_DESC(delay, "Delay (in seconds) between polls to query hypervisor paging requests. "
  63                  "[Default=" __stringify(CMM_DEFAULT_DELAY) "]");
  64 module_param_named(hotplug_delay, hotplug_delay, uint, 0644);
  65 MODULE_PARM_DESC(hotplug_delay, "Delay (in seconds) after memory hotplug remove "
  66                  "before loaning resumes. "
  67                  "[Default=" __stringify(CMM_HOTPLUG_DELAY) "]");
  68 module_param_named(oom_kb, oom_kb, uint, 0644);
  69 MODULE_PARM_DESC(oom_kb, "Amount of memory in kb to free on OOM. "
  70                  "[Default=" __stringify(CMM_OOM_KB) "]");
  71 module_param_named(min_mem_mb, min_mem_mb, ulong, 0644);
  72 MODULE_PARM_DESC(min_mem_mb, "Minimum amount of memory (in MB) to not balloon. "
  73                  "[Default=" __stringify(CMM_MIN_MEM_MB) "]");
  74 module_param_named(debug, cmm_debug, uint, 0644);
  75 MODULE_PARM_DESC(debug, "Enable module debugging logging. Set to 1 to enable. "
  76                  "[Default=" __stringify(CMM_DEBUG) "]");
  77
  78 #define cmm_dbg(...) if (cmm_debug) { printk(KERN_INFO "cmm: "__VA_ARGS__); }
  79
  80 static unsigned long loaned_pages;
  81 static unsigned long loaned_pages_target;
  82 static unsigned long oom_freed_pages;
  83
  84 static LIST_HEAD(cmm_page_list);
  85 static DEFINE_SPINLOCK(cmm_lock);
  86
  87 static DEFINE_MUTEX(hotplug_mutex);
  88 static int hotplug_occurred; /* protected by the hotplug mutex */
  89
  90 static struct task_struct *cmm_thread_ptr;
  91
  92 static long plpar_page_set_loaned(struct page *page)
  93 {
  94         const unsigned long vpa = page_to_phys(page);
  95         unsigned long cmo_page_sz = cmo_get_page_size();
  96         long rc = 0;
  97         int i;
  98
  99         for (i = 0; !rc && i < PAGE_SIZE; i += cmo_page_sz)
 100                 rc = plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_LOANED, vpa + i, 0);
 101
 102         for (i -= cmo_page_sz; rc && i != 0; i -= cmo_page_sz)
 103                 plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_ACTIVE,
 104                                    vpa + i - cmo_page_sz, 0);
 105
 106         return rc;
 107 }
 108
 109 static long plpar_page_set_active(struct page *page)
 110 {
 111         const unsigned long vpa = page_to_phys(page);
 112         unsigned long cmo_page_sz = cmo_get_page_size();
 113         long rc = 0;
 114         int i;
 115
 116         for (i = 0; !rc && i < PAGE_SIZE; i += cmo_page_sz)
 117                 rc = plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_ACTIVE, vpa + i, 0);
 118
 119         for (i -= cmo_page_sz; rc && i != 0; i -= cmo_page_sz)
 120                 plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_LOANED,
 121                                    vpa + i - cmo_page_sz, 0);
 122
 123         return rc;
 124 }
 125
 126 /**
 127  * cmm_alloc_pages - Allocate pages and mark them as loaned
 128  * @nr: number of pages to allocate
 129  *
 130  * Return value:
 131  *      number of pages requested to be allocated which were not
 132  **/
 133 static long cmm_alloc_pages(long nr)
 134 {
 135         struct page *page;
 136         long rc;
 137
 138         cmm_dbg("Begin request for %ld pages\n", nr);
 139
 140         while (nr) {
 141                 /* Exit if a hotplug operation is in progress or occurred */
 142                 if (mutex_trylock(&hotplug_mutex)) {
 143                         if (hotplug_occurred) {
 144                                 mutex_unlock(&hotplug_mutex);
 145                                 break;
 146                         }
 147                         mutex_unlock(&hotplug_mutex);
 148                 } else {
 149                         break;
 150                 }
 151
 152                 page = alloc_page(GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY |
 153                                   __GFP_NOMEMALLOC);
 154                 if (!page)
 155                         break;
 156                 spin_lock(&cmm_lock);
 157                 rc = plpar_page_set_loaned(page);
 158                 if (rc) {
 159                         pr_err("%s: Can not set page to loaned. rc=%ld\n", __func__, rc);
 160                         spin_unlock(&cmm_lock);
 161                         __free_page(page);
 162                         break;
 163                 }
 164
 165                 list_add(&page->lru, &cmm_page_list);
 166                 loaned_pages++;
 167                 totalram_pages_dec();
 168                 spin_unlock(&cmm_lock);
 169                 nr--;
 170         }
 171
 172         cmm_dbg("End request with %ld pages unfulfilled\n", nr);
 173         return nr;
 174 }
 175
 176 /**
 177  * cmm_free_pages - Free pages and mark them as active
 178  * @nr: number of pages to free
 179  *
 180  * Return value:
 181  *      number of pages requested to be freed which were not
 182  **/
 183 static long cmm_free_pages(long nr)
 184 {
 185         struct page *page, *tmp;
 186
 187         cmm_dbg("Begin free of %ld pages.\n", nr);
 188         spin_lock(&cmm_lock);
 189         list_for_each_entry_safe(page, tmp, &cmm_page_list, lru) {
 190                 if (!nr)
 191                         break;
 192                 plpar_page_set_active(page);
 193                 list_del(&page->lru);
 194                 __free_page(page);
 195                 loaned_pages--;
 196                 nr--;
 197                 totalram_pages_inc();
 198         }
 199         spin_unlock(&cmm_lock);
 200         cmm_dbg("End request with %ld pages unfulfilled\n", nr);
 201         return nr;
 202 }
 203
 204 /**
 205  * cmm_oom_notify - OOM notifier
 206  * @self:       notifier block struct
 207  * @dummy:      not used
 208  * @parm:       returned - number of pages freed
 209  *
 210  * Return value:
 211  *      NOTIFY_OK
 212  **/
 213 static int cmm_oom_notify(struct notifier_block *self,
 214                           unsigned long dummy, void *parm)
 215 {
 216         unsigned long *freed = parm;
 217         long nr = KB2PAGES(oom_kb);
 218
 219         cmm_dbg("OOM processing started\n");
 220         nr = cmm_free_pages(nr);
 221         loaned_pages_target = loaned_pages;
 222         *freed += KB2PAGES(oom_kb) - nr;
 223         oom_freed_pages += KB2PAGES(oom_kb) - nr;
 224         cmm_dbg("OOM processing complete\n");
 225         return NOTIFY_OK;
 226 }
 227
 228 /**
 229  * cmm_get_mpp - Read memory performance parameters
 230  *
 231  * Makes hcall to query the current page loan request from the hypervisor.
 232  *
 233  * Return value:
 234  *      nothing
 235  **/
 236 static void cmm_get_mpp(void)
 237 {
 238         int rc;
 239         struct hvcall_mpp_data mpp_data;
 240         signed long active_pages_target, page_loan_request, target;
 241         signed long total_pages = totalram_pages() + loaned_pages;
 242         signed long min_mem_pages = (min_mem_mb * 1024 * 1024) / PAGE_SIZE;
 243
 244         rc = h_get_mpp(&mpp_data);
 245
 246         if (rc != H_SUCCESS)
 247                 return;
 248
 249         page_loan_request = div_s64((s64)mpp_data.loan_request, PAGE_SIZE);
 250         target = page_loan_request + (signed long)loaned_pages;
 251
 252         if (target < 0 || total_pages < min_mem_pages)
 253                 target = 0;
 254
 255         if (target > oom_freed_pages)
 256                 target -= oom_freed_pages;
 257         else
 258                 target = 0;
 259
 260         active_pages_target = total_pages - target;
 261
 262         if (min_mem_pages > active_pages_target)
 263                 target = total_pages - min_mem_pages;
 264
 265         if (target < 0)
 266                 target = 0;
 267
 268         loaned_pages_target = target;
 269
 270         cmm_dbg("delta = %ld, loaned = %lu, target = %lu, oom = %lu, totalram = %lu\n",
 271                 page_loan_request, loaned_pages, loaned_pages_target,
 272                 oom_freed_pages, totalram_pages());
 273 }
 274
 275 static struct notifier_block cmm_oom_nb = {
 276         .notifier_call = cmm_oom_notify
 277 };
 278
 279 /**
 280  * cmm_thread - CMM task thread
 281  * @dummy:      not used
 282  *
 283  * Return value:
 284  *      0
 285  **/
 286 static int cmm_thread(void *dummy)
 287 {
 288         unsigned long timeleft;
 289
 290         while (1) {
 291                 timeleft = msleep_interruptible(delay * 1000);
 292
 293                 if (kthread_should_stop() || timeleft)
 294                         break;
 295
 296                 if (mutex_trylock(&hotplug_mutex)) {
 297                         if (hotplug_occurred) {
 298                                 hotplug_occurred = 0;
 299                                 mutex_unlock(&hotplug_mutex);
 300                                 cmm_dbg("Hotplug operation has occurred, "
 301                                                 "loaning activity suspended "
 302                                                 "for %d seconds.\n",
 303                                                 hotplug_delay);
 304                                 timeleft = msleep_interruptible(hotplug_delay *
 305                                                 1000);
 306                                 if (kthread_should_stop() || timeleft)
 307                                         break;
 308                                 continue;
 309                         }
 310                         mutex_unlock(&hotplug_mutex);
 311                 } else {
 312                         cmm_dbg("Hotplug operation in progress, activity "
 313                                         "suspended\n");
 314                         continue;
 315                 }
 316
 317                 cmm_get_mpp();
 318
 319                 if (loaned_pages_target > loaned_pages) {
 320                         if (cmm_alloc_pages(loaned_pages_target - loaned_pages))
 321                                 loaned_pages_target = loaned_pages;
 322                 } else if (loaned_pages_target < loaned_pages)
 323                         cmm_free_pages(loaned_pages - loaned_pages_target);
 324         }
 325         return 0;
 326 }
 327
 328 #define CMM_SHOW(name, format, args...)                 \
 329         static ssize_t show_##name(struct device *dev,  \
 330                                    struct device_attribute *attr,       \
 331                                    char *buf)                   \
 332         {                                                       \
 333                 return sprintf(buf, format, ##args);            \
 334         }                                                       \
 335         static DEVICE_ATTR(name, 0444, show_##name, NULL)
 336
 337 CMM_SHOW(loaned_kb, "%lu\n", PAGES2KB(loaned_pages));
 338 CMM_SHOW(loaned_target_kb, "%lu\n", PAGES2KB(loaned_pages_target));
 339
 340 static ssize_t show_oom_pages(struct device *dev,
 341                               struct device_attribute *attr, char *buf)
 342 {
 343         return sprintf(buf, "%lu\n", PAGES2KB(oom_freed_pages));
 344 }
 345
 346 static ssize_t store_oom_pages(struct device *dev,
 347                                struct device_attribute *attr,
 348                                const char *buf, size_t count)
 349 {
 350         unsigned long val = simple_strtoul (buf, NULL, 10);
 351
 352         if (!capable(CAP_SYS_ADMIN))
 353                 return -EPERM;
 354         if (val != 0)
 355                 return -EBADMSG;
 356
 357         oom_freed_pages = 0;
 358         return count;
 359 }
 360
 361 static DEVICE_ATTR(oom_freed_kb, 0644,
 362                    show_oom_pages, store_oom_pages);
 363
 364 static struct device_attribute *cmm_attrs[] = {
 365         &dev_attr_loaned_kb,
 366         &dev_attr_loaned_target_kb,
 367         &dev_attr_oom_freed_kb,
 368 };
 369
 370 static struct bus_type cmm_subsys = {
 371         .name = "cmm",
 372         .dev_name = "cmm",
 373 };
 374
 375 static void cmm_release_device(struct device *dev)
 376 {
 377 }
 378
 379 /**
 380  * cmm_sysfs_register - Register with sysfs
 381  *
 382  * Return value:
 383  *      0 on success / other on failure
 384  **/
 385 static int cmm_sysfs_register(struct device *dev)
 386 {
 387         int i, rc;
 388
 389         if ((rc = subsys_system_register(&cmm_subsys, NULL)))
 390                 return rc;
 391
 392         dev->id = 0;
 393         dev->bus = &cmm_subsys;
 394         dev->release = cmm_release_device;
 395
 396         if ((rc = device_register(dev)))
 397                 goto subsys_unregister;
 398
 399         for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++) {
 400                 if ((rc = device_create_file(dev, cmm_attrs[i])))
 401                         goto fail;
 402         }
 403
 404         return 0;
 405
 406 fail:
 407         while (--i >= 0)
 408                 device_remove_file(dev, cmm_attrs[i]);
 409         device_unregister(dev);
 410 subsys_unregister:
 411         bus_unregister(&cmm_subsys);
 412         return rc;
 413 }
 414
 415 /**
 416  * cmm_unregister_sysfs - Unregister from sysfs
 417  *
 418  **/
 419 static void cmm_unregister_sysfs(struct device *dev)
 420 {
 421         int i;
 422
 423         for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++)
 424                 device_remove_file(dev, cmm_attrs[i]);
 425         device_unregister(dev);
 426         bus_unregister(&cmm_subsys);
 427 }
 428
 429 /**
 430  * cmm_reboot_notifier - Make sure pages are not still marked as "loaned"
 431  *
 432  **/
 433 static int cmm_reboot_notifier(struct notifier_block *nb,
 434                                unsigned long action, void *unused)
 435 {
 436         if (action == SYS_RESTART) {
 437                 if (cmm_thread_ptr)
 438                         kthread_stop(cmm_thread_ptr);
 439                 cmm_thread_ptr = NULL;
 440                 cmm_free_pages(loaned_pages);
 441         }
 442         return NOTIFY_DONE;
 443 }
 444
 445 static struct notifier_block cmm_reboot_nb = {
 446         .notifier_call = cmm_reboot_notifier,
 447 };
 448
 449 /**
 450  * cmm_count_pages - Count the number of pages loaned in a particular range.
 451  *
 452  * @arg: memory_isolate_notify structure with address range and count
 453  *
 454  * Return value:
 455  *      0 on success
 456  **/
 457 static unsigned long cmm_count_pages(void *arg)
 458 {
 459         struct memory_isolate_notify *marg = arg;
 460         struct page *page;
 461
 462         spin_lock(&cmm_lock);
 463         list_for_each_entry(page, &cmm_page_list, lru) {
 464                 if (page_to_pfn(page) >= marg->start_pfn &&
 465                     page_to_pfn(page) < marg->start_pfn + marg->nr_pages)
 466                         marg->pages_found++;
 467         }
 468         spin_unlock(&cmm_lock);
 469         return 0;
 470 }
 471
 472 /**
 473  * cmm_memory_isolate_cb - Handle memory isolation notifier calls
 474  * @self:       notifier block struct
 475  * @action:     action to take
 476  * @arg:        struct memory_isolate_notify data for handler
 477  *
 478  * Return value:
 479  *      NOTIFY_OK or notifier error based on subfunction return value
 480  **/
 481 static int cmm_memory_isolate_cb(struct notifier_block *self,
 482                                  unsigned long action, void *arg)
 483 {
 484         int ret = 0;
 485
 486         if (action == MEM_ISOLATE_COUNT)
 487                 ret = cmm_count_pages(arg);
 488
 489         return notifier_from_errno(ret);
 490 }
 491
 492 static struct notifier_block cmm_mem_isolate_nb = {
 493         .notifier_call = cmm_memory_isolate_cb,
 494         .priority = CMM_MEM_ISOLATE_PRI
 495 };
 496
 497 /**
 498  * cmm_mem_going_offline - Unloan pages where memory is to be removed
 499  * @arg: memory_notify structure with page range to be offlined
 500  *
 501  * Return value:
 502  *      0 on success
 503  **/
 504 static int cmm_mem_going_offline(void *arg)
 505 {
 506         struct memory_notify *marg = arg;
 507         struct page *page, *tmp;
 508         unsigned long freed = 0;
 509
 510         cmm_dbg("Memory going offline, searching PFN 0x%lx (%ld pages).\n",
 511                 marg->start_pfn, marg->nr_pages);
 512         spin_lock(&cmm_lock);
 513
 514         /* Search the page list for pages in the range to be offlined */
 515         list_for_each_entry_safe(page, tmp, &cmm_page_list, lru) {
 516                 if (page_to_pfn(page) < marg->start_pfn ||
 517                     page_to_pfn(page) >= marg->start_pfn + marg->nr_pages)
 518                         continue;
 519                 plpar_page_set_active(page);
 520                 list_del(&page->lru);
 521                 __free_page(page);
 522                 freed++;
 523                 loaned_pages--;
 524                 totalram_pages_inc();
 525         }
 526
 527         spin_unlock(&cmm_lock);
 528         cmm_dbg("Released %ld pages in the search range.\n", freed);
 529
 530         return 0;
 531 }
 532
 533 /**
 534  * cmm_memory_cb - Handle memory hotplug notifier calls
 535  * @self:       notifier block struct
 536  * @action:     action to take
 537  * @arg:        struct memory_notify data for handler
 538  *
 539  * Return value:
 540  *      NOTIFY_OK or notifier error based on subfunction return value
 541  *
 542  **/
 543 static int cmm_memory_cb(struct notifier_block *self,
 544                         unsigned long action, void *arg)
 545 {
 546         int ret = 0;
 547
 548         switch (action) {
 549         case MEM_GOING_OFFLINE:
 550                 mutex_lock(&hotplug_mutex);
 551                 hotplug_occurred = 1;
 552                 ret = cmm_mem_going_offline(arg);
 553                 break;
 554         case MEM_OFFLINE:
 555         case MEM_CANCEL_OFFLINE:
 556                 mutex_unlock(&hotplug_mutex);
 557                 cmm_dbg("Memory offline operation complete.\n");
 558                 break;
 559         case MEM_GOING_ONLINE:
 560         case MEM_ONLINE:
 561         case MEM_CANCEL_ONLINE:
 562                 break;
 563         }
 564
 565         return notifier_from_errno(ret);
 566 }
 567
 568 static struct notifier_block cmm_mem_nb = {
 569         .notifier_call = cmm_memory_cb,
 570         .priority = CMM_MEM_HOTPLUG_PRI
 571 };
 572
 573 /**
 574  * cmm_init - Module initialization
 575  *
 576  * Return value:
 577  *      0 on success / other on failure
 578  **/
 579 static int cmm_init(void)
 580 {
 581         int rc;
 582
 583         if (!firmware_has_feature(FW_FEATURE_CMO))
 584                 return -EOPNOTSUPP;
 585
 586         if ((rc = register_oom_notifier(&cmm_oom_nb)) < 0)
 587                 return rc;
 588
 589         if ((rc = register_reboot_notifier(&cmm_reboot_nb)))
 590                 goto out_oom_notifier;
 591
 592         if ((rc = cmm_sysfs_register(&cmm_dev)))
 593                 goto out_reboot_notifier;
 594
 595         rc = register_memory_notifier(&cmm_mem_nb);
 596         if (rc)
 597                 goto out_unregister_notifier;
 598
 599         rc = register_memory_isolate_notifier(&cmm_mem_isolate_nb);
 600         if (rc)
 601                 goto out_unregister_notifier;
 602
 603         if (cmm_disabled)
 604                 return 0;
 605
 606         cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
 607         if (IS_ERR(cmm_thread_ptr)) {
 608                 rc = PTR_ERR(cmm_thread_ptr);
 609                 goto out_unregister_notifier;
 610         }
 611
 612         return 0;
 613 out_unregister_notifier:
 614         unregister_memory_notifier(&cmm_mem_nb);
 615         unregister_memory_isolate_notifier(&cmm_mem_isolate_nb);
 616         cmm_unregister_sysfs(&cmm_dev);
 617 out_reboot_notifier:
 618         unregister_reboot_notifier(&cmm_reboot_nb);
 619 out_oom_notifier:
 620         unregister_oom_notifier(&cmm_oom_nb);
 621         return rc;
 622 }
 623
 624 /**
 625  * cmm_exit - Module exit
 626  *
 627  * Return value:
 628  *      nothing
 629  **/
 630 static void cmm_exit(void)
 631 {
 632         if (cmm_thread_ptr)
 633                 kthread_stop(cmm_thread_ptr);
 634         unregister_oom_notifier(&cmm_oom_nb);
 635         unregister_reboot_notifier(&cmm_reboot_nb);
 636         unregister_memory_notifier(&cmm_mem_nb);
 637         unregister_memory_isolate_notifier(&cmm_mem_isolate_nb);
 638         cmm_free_pages(loaned_pages);
 639         cmm_unregister_sysfs(&cmm_dev);
 640 }
 641
 642 /**
 643  * cmm_set_disable - Disable/Enable CMM
 644  *
 645  * Return value:
 646  *      0 on success / other on failure
 647  **/
 648 static int cmm_set_disable(const char *val, const struct kernel_param *kp)
 649 {
 650         int disable = simple_strtoul(val, NULL, 10);
 651
 652         if (disable != 0 && disable != 1)
 653                 return -EINVAL;
 654
 655         if (disable && !cmm_disabled) {
 656                 if (cmm_thread_ptr)
 657                         kthread_stop(cmm_thread_ptr);
 658                 cmm_thread_ptr = NULL;
 659                 cmm_free_pages(loaned_pages);
 660         } else if (!disable && cmm_disabled) {
 661                 cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
 662                 if (IS_ERR(cmm_thread_ptr))
 663                         return PTR_ERR(cmm_thread_ptr);
 664         }
 665
 666         cmm_disabled = disable;
 667         return 0;
 668 }
 669
 670 module_param_call(disable, cmm_set_disable, param_get_uint,
 671                   &cmm_disabled, 0644);
 672 MODULE_PARM_DESC(disable, "Disable CMM. Set to 1 to disable. "
 673                  "[Default=" __stringify(CMM_DISABLE) "]");
 674
 675 module_init(cmm_init);
 676 module_exit(cmm_exit);