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/init.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/sysdev.h> 36 #include <asm/firmware.h> 37 #include <asm/hvcall.h> 38 #include <asm/mmu.h> 39 #include <asm/pgalloc.h> 40 #include <asm/uaccess.h> 41 #include <linux/memory.h> 42 43 #include "plpar_wrappers.h" 44 45 #define CMM_DRIVER_VERSION "1.0.0" 46 #define CMM_DEFAULT_DELAY 1 47 #define CMM_HOTPLUG_DELAY 5 48 #define CMM_DEBUG 0 49 #define CMM_DISABLE 0 50 #define CMM_OOM_KB 1024 51 #define CMM_MIN_MEM_MB 256 52 #define KB2PAGES(_p) ((_p)>>(PAGE_SHIFT-10)) 53 #define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10)) 54 /* 55 * The priority level tries to ensure that this notifier is called as 56 * late as possible to reduce thrashing in the shared memory pool. 57 */ 58 #define CMM_MEM_HOTPLUG_PRI 1 59 #define CMM_MEM_ISOLATE_PRI 15 60 61 static unsigned int delay = CMM_DEFAULT_DELAY; 62 static unsigned int hotplug_delay = CMM_HOTPLUG_DELAY; 63 static unsigned int oom_kb = CMM_OOM_KB; 64 static unsigned int cmm_debug = CMM_DEBUG; 65 static unsigned int cmm_disabled = CMM_DISABLE; 66 static unsigned long min_mem_mb = CMM_MIN_MEM_MB; 67 static struct sys_device cmm_sysdev; 68 69 MODULE_AUTHOR("Brian King <brking@linux.vnet.ibm.com>"); 70 MODULE_DESCRIPTION("IBM System p Collaborative Memory Manager"); 71 MODULE_LICENSE("GPL"); 72 MODULE_VERSION(CMM_DRIVER_VERSION); 73 74 module_param_named(delay, delay, uint, S_IRUGO | S_IWUSR); 75 MODULE_PARM_DESC(delay, "Delay (in seconds) between polls to query hypervisor paging requests. " 76 "[Default=" __stringify(CMM_DEFAULT_DELAY) "]"); 77 module_param_named(hotplug_delay, hotplug_delay, uint, S_IRUGO | S_IWUSR); 78 MODULE_PARM_DESC(delay, "Delay (in seconds) after memory hotplug remove " 79 "before loaning resumes. " 80 "[Default=" __stringify(CMM_HOTPLUG_DELAY) "]"); 81 module_param_named(oom_kb, oom_kb, uint, S_IRUGO | S_IWUSR); 82 MODULE_PARM_DESC(oom_kb, "Amount of memory in kb to free on OOM. " 83 "[Default=" __stringify(CMM_OOM_KB) "]"); 84 module_param_named(min_mem_mb, min_mem_mb, ulong, S_IRUGO | S_IWUSR); 85 MODULE_PARM_DESC(min_mem_mb, "Minimum amount of memory (in MB) to not balloon. " 86 "[Default=" __stringify(CMM_MIN_MEM_MB) "]"); 87 module_param_named(debug, cmm_debug, uint, S_IRUGO | S_IWUSR); 88 MODULE_PARM_DESC(debug, "Enable module debugging logging. Set to 1 to enable. " 89 "[Default=" __stringify(CMM_DEBUG) "]"); 90 91 #define CMM_NR_PAGES ((PAGE_SIZE - sizeof(void *) - sizeof(unsigned long)) / sizeof(unsigned long)) 92 93 #define cmm_dbg(...) if (cmm_debug) { printk(KERN_INFO "cmm: "__VA_ARGS__); } 94 95 struct cmm_page_array { 96 struct cmm_page_array *next; 97 unsigned long index; 98 unsigned long page[CMM_NR_PAGES]; 99 }; 100 101 static unsigned long loaned_pages; 102 static unsigned long loaned_pages_target; 103 static unsigned long oom_freed_pages; 104 105 static struct cmm_page_array *cmm_page_list; 106 static DEFINE_SPINLOCK(cmm_lock); 107 108 static DEFINE_MUTEX(hotplug_mutex); 109 static int hotplug_occurred; /* protected by the hotplug mutex */ 110 111 static struct task_struct *cmm_thread_ptr; 112 113 /** 114 * cmm_alloc_pages - Allocate pages and mark them as loaned 115 * @nr: number of pages to allocate 116 * 117 * Return value: 118 * number of pages requested to be allocated which were not 119 **/ 120 static long cmm_alloc_pages(long nr) 121 { 122 struct cmm_page_array *pa, *npa; 123 unsigned long addr; 124 long rc; 125 126 cmm_dbg("Begin request for %ld pages\n", nr); 127 128 while (nr) { 129 /* Exit if a hotplug operation is in progress or occurred */ 130 if (mutex_trylock(&hotplug_mutex)) { 131 if (hotplug_occurred) { 132 mutex_unlock(&hotplug_mutex); 133 break; 134 } 135 mutex_unlock(&hotplug_mutex); 136 } else { 137 break; 138 } 139 140 addr = __get_free_page(GFP_NOIO | __GFP_NOWARN | 141 __GFP_NORETRY | __GFP_NOMEMALLOC); 142 if (!addr) 143 break; 144 spin_lock(&cmm_lock); 145 pa = cmm_page_list; 146 if (!pa || pa->index >= CMM_NR_PAGES) { 147 /* Need a new page for the page list. */ 148 spin_unlock(&cmm_lock); 149 npa = (struct cmm_page_array *)__get_free_page( 150 GFP_NOIO | __GFP_NOWARN | 151 __GFP_NORETRY | __GFP_NOMEMALLOC); 152 if (!npa) { 153 pr_info("%s: Can not allocate new page list\n", __func__); 154 free_page(addr); 155 break; 156 } 157 spin_lock(&cmm_lock); 158 pa = cmm_page_list; 159 160 if (!pa || pa->index >= CMM_NR_PAGES) { 161 npa->next = pa; 162 npa->index = 0; 163 pa = npa; 164 cmm_page_list = pa; 165 } else 166 free_page((unsigned long) npa); 167 } 168 169 if ((rc = plpar_page_set_loaned(__pa(addr)))) { 170 pr_err("%s: Can not set page to loaned. rc=%ld\n", __func__, rc); 171 spin_unlock(&cmm_lock); 172 free_page(addr); 173 break; 174 } 175 176 pa->page[pa->index++] = addr; 177 loaned_pages++; 178 totalram_pages--; 179 spin_unlock(&cmm_lock); 180 nr--; 181 } 182 183 cmm_dbg("End request with %ld pages unfulfilled\n", nr); 184 return nr; 185 } 186 187 /** 188 * cmm_free_pages - Free pages and mark them as active 189 * @nr: number of pages to free 190 * 191 * Return value: 192 * number of pages requested to be freed which were not 193 **/ 194 static long cmm_free_pages(long nr) 195 { 196 struct cmm_page_array *pa; 197 unsigned long addr; 198 199 cmm_dbg("Begin free of %ld pages.\n", nr); 200 spin_lock(&cmm_lock); 201 pa = cmm_page_list; 202 while (nr) { 203 if (!pa || pa->index <= 0) 204 break; 205 addr = pa->page[--pa->index]; 206 207 if (pa->index == 0) { 208 pa = pa->next; 209 free_page((unsigned long) cmm_page_list); 210 cmm_page_list = pa; 211 } 212 213 plpar_page_set_active(__pa(addr)); 214 free_page(addr); 215 loaned_pages--; 216 nr--; 217 totalram_pages++; 218 } 219 spin_unlock(&cmm_lock); 220 cmm_dbg("End request with %ld pages unfulfilled\n", nr); 221 return nr; 222 } 223 224 /** 225 * cmm_oom_notify - OOM notifier 226 * @self: notifier block struct 227 * @dummy: not used 228 * @parm: returned - number of pages freed 229 * 230 * Return value: 231 * NOTIFY_OK 232 **/ 233 static int cmm_oom_notify(struct notifier_block *self, 234 unsigned long dummy, void *parm) 235 { 236 unsigned long *freed = parm; 237 long nr = KB2PAGES(oom_kb); 238 239 cmm_dbg("OOM processing started\n"); 240 nr = cmm_free_pages(nr); 241 loaned_pages_target = loaned_pages; 242 *freed += KB2PAGES(oom_kb) - nr; 243 oom_freed_pages += KB2PAGES(oom_kb) - nr; 244 cmm_dbg("OOM processing complete\n"); 245 return NOTIFY_OK; 246 } 247 248 /** 249 * cmm_get_mpp - Read memory performance parameters 250 * 251 * Makes hcall to query the current page loan request from the hypervisor. 252 * 253 * Return value: 254 * nothing 255 **/ 256 static void cmm_get_mpp(void) 257 { 258 int rc; 259 struct hvcall_mpp_data mpp_data; 260 signed long active_pages_target, page_loan_request, target; 261 signed long total_pages = totalram_pages + loaned_pages; 262 signed long min_mem_pages = (min_mem_mb * 1024 * 1024) / PAGE_SIZE; 263 264 rc = h_get_mpp(&mpp_data); 265 266 if (rc != H_SUCCESS) 267 return; 268 269 page_loan_request = div_s64((s64)mpp_data.loan_request, PAGE_SIZE); 270 target = page_loan_request + (signed long)loaned_pages; 271 272 if (target < 0 || total_pages < min_mem_pages) 273 target = 0; 274 275 if (target > oom_freed_pages) 276 target -= oom_freed_pages; 277 else 278 target = 0; 279 280 active_pages_target = total_pages - target; 281 282 if (min_mem_pages > active_pages_target) 283 target = total_pages - min_mem_pages; 284 285 if (target < 0) 286 target = 0; 287 288 loaned_pages_target = target; 289 290 cmm_dbg("delta = %ld, loaned = %lu, target = %lu, oom = %lu, totalram = %lu\n", 291 page_loan_request, loaned_pages, loaned_pages_target, 292 oom_freed_pages, totalram_pages); 293 } 294 295 static struct notifier_block cmm_oom_nb = { 296 .notifier_call = cmm_oom_notify 297 }; 298 299 /** 300 * cmm_thread - CMM task thread 301 * @dummy: not used 302 * 303 * Return value: 304 * 0 305 **/ 306 static int cmm_thread(void *dummy) 307 { 308 unsigned long timeleft; 309 310 while (1) { 311 timeleft = msleep_interruptible(delay * 1000); 312 313 if (kthread_should_stop() || timeleft) 314 break; 315 316 if (mutex_trylock(&hotplug_mutex)) { 317 if (hotplug_occurred) { 318 hotplug_occurred = 0; 319 mutex_unlock(&hotplug_mutex); 320 cmm_dbg("Hotplug operation has occurred, " 321 "loaning activity suspended " 322 "for %d seconds.\n", 323 hotplug_delay); 324 timeleft = msleep_interruptible(hotplug_delay * 325 1000); 326 if (kthread_should_stop() || timeleft) 327 break; 328 continue; 329 } 330 mutex_unlock(&hotplug_mutex); 331 } else { 332 cmm_dbg("Hotplug operation in progress, activity " 333 "suspended\n"); 334 continue; 335 } 336 337 cmm_get_mpp(); 338 339 if (loaned_pages_target > loaned_pages) { 340 if (cmm_alloc_pages(loaned_pages_target - loaned_pages)) 341 loaned_pages_target = loaned_pages; 342 } else if (loaned_pages_target < loaned_pages) 343 cmm_free_pages(loaned_pages - loaned_pages_target); 344 } 345 return 0; 346 } 347 348 #define CMM_SHOW(name, format, args...) \ 349 static ssize_t show_##name(struct sys_device *dev, \ 350 struct sysdev_attribute *attr, \ 351 char *buf) \ 352 { \ 353 return sprintf(buf, format, ##args); \ 354 } \ 355 static SYSDEV_ATTR(name, S_IRUGO, show_##name, NULL) 356 357 CMM_SHOW(loaned_kb, "%lu\n", PAGES2KB(loaned_pages)); 358 CMM_SHOW(loaned_target_kb, "%lu\n", PAGES2KB(loaned_pages_target)); 359 360 static ssize_t show_oom_pages(struct sys_device *dev, 361 struct sysdev_attribute *attr, char *buf) 362 { 363 return sprintf(buf, "%lu\n", PAGES2KB(oom_freed_pages)); 364 } 365 366 static ssize_t store_oom_pages(struct sys_device *dev, 367 struct sysdev_attribute *attr, 368 const char *buf, size_t count) 369 { 370 unsigned long val = simple_strtoul (buf, NULL, 10); 371 372 if (!capable(CAP_SYS_ADMIN)) 373 return -EPERM; 374 if (val != 0) 375 return -EBADMSG; 376 377 oom_freed_pages = 0; 378 return count; 379 } 380 381 static SYSDEV_ATTR(oom_freed_kb, S_IWUSR| S_IRUGO, 382 show_oom_pages, store_oom_pages); 383 384 static struct sysdev_attribute *cmm_attrs[] = { 385 &attr_loaned_kb, 386 &attr_loaned_target_kb, 387 &attr_oom_freed_kb, 388 }; 389 390 static struct sysdev_class cmm_sysdev_class = { 391 .name = "cmm", 392 }; 393 394 /** 395 * cmm_sysfs_register - Register with sysfs 396 * 397 * Return value: 398 * 0 on success / other on failure 399 **/ 400 static int cmm_sysfs_register(struct sys_device *sysdev) 401 { 402 int i, rc; 403 404 if ((rc = sysdev_class_register(&cmm_sysdev_class))) 405 return rc; 406 407 sysdev->id = 0; 408 sysdev->cls = &cmm_sysdev_class; 409 410 if ((rc = sysdev_register(sysdev))) 411 goto class_unregister; 412 413 for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++) { 414 if ((rc = sysdev_create_file(sysdev, cmm_attrs[i]))) 415 goto fail; 416 } 417 418 return 0; 419 420 fail: 421 while (--i >= 0) 422 sysdev_remove_file(sysdev, cmm_attrs[i]); 423 sysdev_unregister(sysdev); 424 class_unregister: 425 sysdev_class_unregister(&cmm_sysdev_class); 426 return rc; 427 } 428 429 /** 430 * cmm_unregister_sysfs - Unregister from sysfs 431 * 432 **/ 433 static void cmm_unregister_sysfs(struct sys_device *sysdev) 434 { 435 int i; 436 437 for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++) 438 sysdev_remove_file(sysdev, cmm_attrs[i]); 439 sysdev_unregister(sysdev); 440 sysdev_class_unregister(&cmm_sysdev_class); 441 } 442 443 /** 444 * cmm_reboot_notifier - Make sure pages are not still marked as "loaned" 445 * 446 **/ 447 static int cmm_reboot_notifier(struct notifier_block *nb, 448 unsigned long action, void *unused) 449 { 450 if (action == SYS_RESTART) { 451 if (cmm_thread_ptr) 452 kthread_stop(cmm_thread_ptr); 453 cmm_thread_ptr = NULL; 454 cmm_free_pages(loaned_pages); 455 } 456 return NOTIFY_DONE; 457 } 458 459 static struct notifier_block cmm_reboot_nb = { 460 .notifier_call = cmm_reboot_notifier, 461 }; 462 463 /** 464 * cmm_count_pages - Count the number of pages loaned in a particular range. 465 * 466 * @arg: memory_isolate_notify structure with address range and count 467 * 468 * Return value: 469 * 0 on success 470 **/ 471 static unsigned long cmm_count_pages(void *arg) 472 { 473 struct memory_isolate_notify *marg = arg; 474 struct cmm_page_array *pa; 475 unsigned long start = (unsigned long)pfn_to_kaddr(marg->start_pfn); 476 unsigned long end = start + (marg->nr_pages << PAGE_SHIFT); 477 unsigned long idx; 478 479 spin_lock(&cmm_lock); 480 pa = cmm_page_list; 481 while (pa) { 482 if ((unsigned long)pa >= start && (unsigned long)pa < end) 483 marg->pages_found++; 484 for (idx = 0; idx < pa->index; idx++) 485 if (pa->page[idx] >= start && pa->page[idx] < end) 486 marg->pages_found++; 487 pa = pa->next; 488 } 489 spin_unlock(&cmm_lock); 490 return 0; 491 } 492 493 /** 494 * cmm_memory_isolate_cb - Handle memory isolation notifier calls 495 * @self: notifier block struct 496 * @action: action to take 497 * @arg: struct memory_isolate_notify data for handler 498 * 499 * Return value: 500 * NOTIFY_OK or notifier error based on subfunction return value 501 **/ 502 static int cmm_memory_isolate_cb(struct notifier_block *self, 503 unsigned long action, void *arg) 504 { 505 int ret = 0; 506 507 if (action == MEM_ISOLATE_COUNT) 508 ret = cmm_count_pages(arg); 509 510 if (ret) 511 ret = notifier_from_errno(ret); 512 else 513 ret = NOTIFY_OK; 514 515 return ret; 516 } 517 518 static struct notifier_block cmm_mem_isolate_nb = { 519 .notifier_call = cmm_memory_isolate_cb, 520 .priority = CMM_MEM_ISOLATE_PRI 521 }; 522 523 /** 524 * cmm_mem_going_offline - Unloan pages where memory is to be removed 525 * @arg: memory_notify structure with page range to be offlined 526 * 527 * Return value: 528 * 0 on success 529 **/ 530 static int cmm_mem_going_offline(void *arg) 531 { 532 struct memory_notify *marg = arg; 533 unsigned long start_page = (unsigned long)pfn_to_kaddr(marg->start_pfn); 534 unsigned long end_page = start_page + (marg->nr_pages << PAGE_SHIFT); 535 struct cmm_page_array *pa_curr, *pa_last, *npa; 536 unsigned long idx; 537 unsigned long freed = 0; 538 539 cmm_dbg("Memory going offline, searching 0x%lx (%ld pages).\n", 540 start_page, marg->nr_pages); 541 spin_lock(&cmm_lock); 542 543 /* Search the page list for pages in the range to be offlined */ 544 pa_last = pa_curr = cmm_page_list; 545 while (pa_curr) { 546 for (idx = (pa_curr->index - 1); (idx + 1) > 0; idx--) { 547 if ((pa_curr->page[idx] < start_page) || 548 (pa_curr->page[idx] >= end_page)) 549 continue; 550 551 plpar_page_set_active(__pa(pa_curr->page[idx])); 552 free_page(pa_curr->page[idx]); 553 freed++; 554 loaned_pages--; 555 totalram_pages++; 556 pa_curr->page[idx] = pa_last->page[--pa_last->index]; 557 if (pa_last->index == 0) { 558 if (pa_curr == pa_last) 559 pa_curr = pa_last->next; 560 pa_last = pa_last->next; 561 free_page((unsigned long)cmm_page_list); 562 cmm_page_list = pa_last; 563 continue; 564 } 565 } 566 pa_curr = pa_curr->next; 567 } 568 569 /* Search for page list structures in the range to be offlined */ 570 pa_last = NULL; 571 pa_curr = cmm_page_list; 572 while (pa_curr) { 573 if (((unsigned long)pa_curr >= start_page) && 574 ((unsigned long)pa_curr < end_page)) { 575 npa = (struct cmm_page_array *)__get_free_page( 576 GFP_NOIO | __GFP_NOWARN | 577 __GFP_NORETRY | __GFP_NOMEMALLOC); 578 if (!npa) { 579 spin_unlock(&cmm_lock); 580 cmm_dbg("Failed to allocate memory for list " 581 "management. Memory hotplug " 582 "failed.\n"); 583 return ENOMEM; 584 } 585 memcpy(npa, pa_curr, PAGE_SIZE); 586 if (pa_curr == cmm_page_list) 587 cmm_page_list = npa; 588 if (pa_last) 589 pa_last->next = npa; 590 free_page((unsigned long) pa_curr); 591 freed++; 592 pa_curr = npa; 593 } 594 595 pa_last = pa_curr; 596 pa_curr = pa_curr->next; 597 } 598 599 spin_unlock(&cmm_lock); 600 cmm_dbg("Released %ld pages in the search range.\n", freed); 601 602 return 0; 603 } 604 605 /** 606 * cmm_memory_cb - Handle memory hotplug notifier calls 607 * @self: notifier block struct 608 * @action: action to take 609 * @arg: struct memory_notify data for handler 610 * 611 * Return value: 612 * NOTIFY_OK or notifier error based on subfunction return value 613 * 614 **/ 615 static int cmm_memory_cb(struct notifier_block *self, 616 unsigned long action, void *arg) 617 { 618 int ret = 0; 619 620 switch (action) { 621 case MEM_GOING_OFFLINE: 622 mutex_lock(&hotplug_mutex); 623 hotplug_occurred = 1; 624 ret = cmm_mem_going_offline(arg); 625 break; 626 case MEM_OFFLINE: 627 case MEM_CANCEL_OFFLINE: 628 mutex_unlock(&hotplug_mutex); 629 cmm_dbg("Memory offline operation complete.\n"); 630 break; 631 case MEM_GOING_ONLINE: 632 case MEM_ONLINE: 633 case MEM_CANCEL_ONLINE: 634 break; 635 } 636 637 if (ret) 638 ret = notifier_from_errno(ret); 639 else 640 ret = NOTIFY_OK; 641 642 return ret; 643 } 644 645 static struct notifier_block cmm_mem_nb = { 646 .notifier_call = cmm_memory_cb, 647 .priority = CMM_MEM_HOTPLUG_PRI 648 }; 649 650 /** 651 * cmm_init - Module initialization 652 * 653 * Return value: 654 * 0 on success / other on failure 655 **/ 656 static int cmm_init(void) 657 { 658 int rc = -ENOMEM; 659 660 if (!firmware_has_feature(FW_FEATURE_CMO)) 661 return -EOPNOTSUPP; 662 663 if ((rc = register_oom_notifier(&cmm_oom_nb)) < 0) 664 return rc; 665 666 if ((rc = register_reboot_notifier(&cmm_reboot_nb))) 667 goto out_oom_notifier; 668 669 if ((rc = cmm_sysfs_register(&cmm_sysdev))) 670 goto out_reboot_notifier; 671 672 if (register_memory_notifier(&cmm_mem_nb) || 673 register_memory_isolate_notifier(&cmm_mem_isolate_nb)) 674 goto out_unregister_notifier; 675 676 if (cmm_disabled) 677 return rc; 678 679 cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread"); 680 if (IS_ERR(cmm_thread_ptr)) { 681 rc = PTR_ERR(cmm_thread_ptr); 682 goto out_unregister_notifier; 683 } 684 685 return rc; 686 687 out_unregister_notifier: 688 unregister_memory_notifier(&cmm_mem_nb); 689 unregister_memory_isolate_notifier(&cmm_mem_isolate_nb); 690 cmm_unregister_sysfs(&cmm_sysdev); 691 out_reboot_notifier: 692 unregister_reboot_notifier(&cmm_reboot_nb); 693 out_oom_notifier: 694 unregister_oom_notifier(&cmm_oom_nb); 695 return rc; 696 } 697 698 /** 699 * cmm_exit - Module exit 700 * 701 * Return value: 702 * nothing 703 **/ 704 static void cmm_exit(void) 705 { 706 if (cmm_thread_ptr) 707 kthread_stop(cmm_thread_ptr); 708 unregister_oom_notifier(&cmm_oom_nb); 709 unregister_reboot_notifier(&cmm_reboot_nb); 710 unregister_memory_notifier(&cmm_mem_nb); 711 unregister_memory_isolate_notifier(&cmm_mem_isolate_nb); 712 cmm_free_pages(loaned_pages); 713 cmm_unregister_sysfs(&cmm_sysdev); 714 } 715 716 /** 717 * cmm_set_disable - Disable/Enable CMM 718 * 719 * Return value: 720 * 0 on success / other on failure 721 **/ 722 static int cmm_set_disable(const char *val, struct kernel_param *kp) 723 { 724 int disable = simple_strtoul(val, NULL, 10); 725 726 if (disable != 0 && disable != 1) 727 return -EINVAL; 728 729 if (disable && !cmm_disabled) { 730 if (cmm_thread_ptr) 731 kthread_stop(cmm_thread_ptr); 732 cmm_thread_ptr = NULL; 733 cmm_free_pages(loaned_pages); 734 } else if (!disable && cmm_disabled) { 735 cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread"); 736 if (IS_ERR(cmm_thread_ptr)) 737 return PTR_ERR(cmm_thread_ptr); 738 } 739 740 cmm_disabled = disable; 741 return 0; 742 } 743 744 module_param_call(disable, cmm_set_disable, param_get_uint, 745 &cmm_disabled, S_IRUGO | S_IWUSR); 746 MODULE_PARM_DESC(disable, "Disable CMM. Set to 1 to disable. " 747 "[Default=" __stringify(CMM_DISABLE) "]"); 748 749 module_init(cmm_init); 750 module_exit(cmm_exit); 751