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_NR_PAGES ((PAGE_SIZE - sizeof(void *) - sizeof(unsigned long)) / sizeof(unsigned long)) 79 80 #define cmm_dbg(...) if (cmm_debug) { printk(KERN_INFO "cmm: "__VA_ARGS__); } 81 82 struct cmm_page_array { 83 struct cmm_page_array *next; 84 unsigned long index; 85 unsigned long page[CMM_NR_PAGES]; 86 }; 87 88 static unsigned long loaned_pages; 89 static unsigned long loaned_pages_target; 90 static unsigned long oom_freed_pages; 91 92 static struct cmm_page_array *cmm_page_list; 93 static DEFINE_SPINLOCK(cmm_lock); 94 95 static DEFINE_MUTEX(hotplug_mutex); 96 static int hotplug_occurred; /* protected by the hotplug mutex */ 97 98 static struct task_struct *cmm_thread_ptr; 99 100 static long plpar_page_set_loaned(unsigned long vpa) 101 { 102 unsigned long cmo_page_sz = cmo_get_page_size(); 103 long rc = 0; 104 int i; 105 106 for (i = 0; !rc && i < PAGE_SIZE; i += cmo_page_sz) 107 rc = plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_LOANED, vpa + i, 0); 108 109 for (i -= cmo_page_sz; rc && i != 0; i -= cmo_page_sz) 110 plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_ACTIVE, 111 vpa + i - cmo_page_sz, 0); 112 113 return rc; 114 } 115 116 static long plpar_page_set_active(unsigned long vpa) 117 { 118 unsigned long cmo_page_sz = cmo_get_page_size(); 119 long rc = 0; 120 int i; 121 122 for (i = 0; !rc && i < PAGE_SIZE; i += cmo_page_sz) 123 rc = plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_ACTIVE, vpa + i, 0); 124 125 for (i -= cmo_page_sz; rc && i != 0; i -= cmo_page_sz) 126 plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_LOANED, 127 vpa + i - cmo_page_sz, 0); 128 129 return rc; 130 } 131 132 /** 133 * cmm_alloc_pages - Allocate pages and mark them as loaned 134 * @nr: number of pages to allocate 135 * 136 * Return value: 137 * number of pages requested to be allocated which were not 138 **/ 139 static long cmm_alloc_pages(long nr) 140 { 141 struct cmm_page_array *pa, *npa; 142 unsigned long addr; 143 long rc; 144 145 cmm_dbg("Begin request for %ld pages\n", nr); 146 147 while (nr) { 148 /* Exit if a hotplug operation is in progress or occurred */ 149 if (mutex_trylock(&hotplug_mutex)) { 150 if (hotplug_occurred) { 151 mutex_unlock(&hotplug_mutex); 152 break; 153 } 154 mutex_unlock(&hotplug_mutex); 155 } else { 156 break; 157 } 158 159 addr = __get_free_page(GFP_NOIO | __GFP_NOWARN | 160 __GFP_NORETRY | __GFP_NOMEMALLOC); 161 if (!addr) 162 break; 163 spin_lock(&cmm_lock); 164 pa = cmm_page_list; 165 if (!pa || pa->index >= CMM_NR_PAGES) { 166 /* Need a new page for the page list. */ 167 spin_unlock(&cmm_lock); 168 npa = (struct cmm_page_array *)__get_free_page( 169 GFP_NOIO | __GFP_NOWARN | 170 __GFP_NORETRY | __GFP_NOMEMALLOC); 171 if (!npa) { 172 pr_info("%s: Can not allocate new page list\n", __func__); 173 free_page(addr); 174 break; 175 } 176 spin_lock(&cmm_lock); 177 pa = cmm_page_list; 178 179 if (!pa || pa->index >= CMM_NR_PAGES) { 180 npa->next = pa; 181 npa->index = 0; 182 pa = npa; 183 cmm_page_list = pa; 184 } else 185 free_page((unsigned long) npa); 186 } 187 188 if ((rc = plpar_page_set_loaned(__pa(addr)))) { 189 pr_err("%s: Can not set page to loaned. rc=%ld\n", __func__, rc); 190 spin_unlock(&cmm_lock); 191 free_page(addr); 192 break; 193 } 194 195 pa->page[pa->index++] = addr; 196 loaned_pages++; 197 totalram_pages_dec(); 198 spin_unlock(&cmm_lock); 199 nr--; 200 } 201 202 cmm_dbg("End request with %ld pages unfulfilled\n", nr); 203 return nr; 204 } 205 206 /** 207 * cmm_free_pages - Free pages and mark them as active 208 * @nr: number of pages to free 209 * 210 * Return value: 211 * number of pages requested to be freed which were not 212 **/ 213 static long cmm_free_pages(long nr) 214 { 215 struct cmm_page_array *pa; 216 unsigned long addr; 217 218 cmm_dbg("Begin free of %ld pages.\n", nr); 219 spin_lock(&cmm_lock); 220 pa = cmm_page_list; 221 while (nr) { 222 if (!pa || pa->index <= 0) 223 break; 224 addr = pa->page[--pa->index]; 225 226 if (pa->index == 0) { 227 pa = pa->next; 228 free_page((unsigned long) cmm_page_list); 229 cmm_page_list = pa; 230 } 231 232 plpar_page_set_active(__pa(addr)); 233 free_page(addr); 234 loaned_pages--; 235 nr--; 236 totalram_pages_inc(); 237 } 238 spin_unlock(&cmm_lock); 239 cmm_dbg("End request with %ld pages unfulfilled\n", nr); 240 return nr; 241 } 242 243 /** 244 * cmm_oom_notify - OOM notifier 245 * @self: notifier block struct 246 * @dummy: not used 247 * @parm: returned - number of pages freed 248 * 249 * Return value: 250 * NOTIFY_OK 251 **/ 252 static int cmm_oom_notify(struct notifier_block *self, 253 unsigned long dummy, void *parm) 254 { 255 unsigned long *freed = parm; 256 long nr = KB2PAGES(oom_kb); 257 258 cmm_dbg("OOM processing started\n"); 259 nr = cmm_free_pages(nr); 260 loaned_pages_target = loaned_pages; 261 *freed += KB2PAGES(oom_kb) - nr; 262 oom_freed_pages += KB2PAGES(oom_kb) - nr; 263 cmm_dbg("OOM processing complete\n"); 264 return NOTIFY_OK; 265 } 266 267 /** 268 * cmm_get_mpp - Read memory performance parameters 269 * 270 * Makes hcall to query the current page loan request from the hypervisor. 271 * 272 * Return value: 273 * nothing 274 **/ 275 static void cmm_get_mpp(void) 276 { 277 int rc; 278 struct hvcall_mpp_data mpp_data; 279 signed long active_pages_target, page_loan_request, target; 280 signed long total_pages = totalram_pages() + loaned_pages; 281 signed long min_mem_pages = (min_mem_mb * 1024 * 1024) / PAGE_SIZE; 282 283 rc = h_get_mpp(&mpp_data); 284 285 if (rc != H_SUCCESS) 286 return; 287 288 page_loan_request = div_s64((s64)mpp_data.loan_request, PAGE_SIZE); 289 target = page_loan_request + (signed long)loaned_pages; 290 291 if (target < 0 || total_pages < min_mem_pages) 292 target = 0; 293 294 if (target > oom_freed_pages) 295 target -= oom_freed_pages; 296 else 297 target = 0; 298 299 active_pages_target = total_pages - target; 300 301 if (min_mem_pages > active_pages_target) 302 target = total_pages - min_mem_pages; 303 304 if (target < 0) 305 target = 0; 306 307 loaned_pages_target = target; 308 309 cmm_dbg("delta = %ld, loaned = %lu, target = %lu, oom = %lu, totalram = %lu\n", 310 page_loan_request, loaned_pages, loaned_pages_target, 311 oom_freed_pages, totalram_pages()); 312 } 313 314 static struct notifier_block cmm_oom_nb = { 315 .notifier_call = cmm_oom_notify 316 }; 317 318 /** 319 * cmm_thread - CMM task thread 320 * @dummy: not used 321 * 322 * Return value: 323 * 0 324 **/ 325 static int cmm_thread(void *dummy) 326 { 327 unsigned long timeleft; 328 329 while (1) { 330 timeleft = msleep_interruptible(delay * 1000); 331 332 if (kthread_should_stop() || timeleft) 333 break; 334 335 if (mutex_trylock(&hotplug_mutex)) { 336 if (hotplug_occurred) { 337 hotplug_occurred = 0; 338 mutex_unlock(&hotplug_mutex); 339 cmm_dbg("Hotplug operation has occurred, " 340 "loaning activity suspended " 341 "for %d seconds.\n", 342 hotplug_delay); 343 timeleft = msleep_interruptible(hotplug_delay * 344 1000); 345 if (kthread_should_stop() || timeleft) 346 break; 347 continue; 348 } 349 mutex_unlock(&hotplug_mutex); 350 } else { 351 cmm_dbg("Hotplug operation in progress, activity " 352 "suspended\n"); 353 continue; 354 } 355 356 cmm_get_mpp(); 357 358 if (loaned_pages_target > loaned_pages) { 359 if (cmm_alloc_pages(loaned_pages_target - loaned_pages)) 360 loaned_pages_target = loaned_pages; 361 } else if (loaned_pages_target < loaned_pages) 362 cmm_free_pages(loaned_pages - loaned_pages_target); 363 } 364 return 0; 365 } 366 367 #define CMM_SHOW(name, format, args...) \ 368 static ssize_t show_##name(struct device *dev, \ 369 struct device_attribute *attr, \ 370 char *buf) \ 371 { \ 372 return sprintf(buf, format, ##args); \ 373 } \ 374 static DEVICE_ATTR(name, 0444, show_##name, NULL) 375 376 CMM_SHOW(loaned_kb, "%lu\n", PAGES2KB(loaned_pages)); 377 CMM_SHOW(loaned_target_kb, "%lu\n", PAGES2KB(loaned_pages_target)); 378 379 static ssize_t show_oom_pages(struct device *dev, 380 struct device_attribute *attr, char *buf) 381 { 382 return sprintf(buf, "%lu\n", PAGES2KB(oom_freed_pages)); 383 } 384 385 static ssize_t store_oom_pages(struct device *dev, 386 struct device_attribute *attr, 387 const char *buf, size_t count) 388 { 389 unsigned long val = simple_strtoul (buf, NULL, 10); 390 391 if (!capable(CAP_SYS_ADMIN)) 392 return -EPERM; 393 if (val != 0) 394 return -EBADMSG; 395 396 oom_freed_pages = 0; 397 return count; 398 } 399 400 static DEVICE_ATTR(oom_freed_kb, 0644, 401 show_oom_pages, store_oom_pages); 402 403 static struct device_attribute *cmm_attrs[] = { 404 &dev_attr_loaned_kb, 405 &dev_attr_loaned_target_kb, 406 &dev_attr_oom_freed_kb, 407 }; 408 409 static struct bus_type cmm_subsys = { 410 .name = "cmm", 411 .dev_name = "cmm", 412 }; 413 414 /** 415 * cmm_sysfs_register - Register with sysfs 416 * 417 * Return value: 418 * 0 on success / other on failure 419 **/ 420 static int cmm_sysfs_register(struct device *dev) 421 { 422 int i, rc; 423 424 if ((rc = subsys_system_register(&cmm_subsys, NULL))) 425 return rc; 426 427 dev->id = 0; 428 dev->bus = &cmm_subsys; 429 430 if ((rc = device_register(dev))) 431 goto subsys_unregister; 432 433 for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++) { 434 if ((rc = device_create_file(dev, cmm_attrs[i]))) 435 goto fail; 436 } 437 438 return 0; 439 440 fail: 441 while (--i >= 0) 442 device_remove_file(dev, cmm_attrs[i]); 443 device_unregister(dev); 444 subsys_unregister: 445 bus_unregister(&cmm_subsys); 446 return rc; 447 } 448 449 /** 450 * cmm_unregister_sysfs - Unregister from sysfs 451 * 452 **/ 453 static void cmm_unregister_sysfs(struct device *dev) 454 { 455 int i; 456 457 for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++) 458 device_remove_file(dev, cmm_attrs[i]); 459 device_unregister(dev); 460 bus_unregister(&cmm_subsys); 461 } 462 463 /** 464 * cmm_reboot_notifier - Make sure pages are not still marked as "loaned" 465 * 466 **/ 467 static int cmm_reboot_notifier(struct notifier_block *nb, 468 unsigned long action, void *unused) 469 { 470 if (action == SYS_RESTART) { 471 if (cmm_thread_ptr) 472 kthread_stop(cmm_thread_ptr); 473 cmm_thread_ptr = NULL; 474 cmm_free_pages(loaned_pages); 475 } 476 return NOTIFY_DONE; 477 } 478 479 static struct notifier_block cmm_reboot_nb = { 480 .notifier_call = cmm_reboot_notifier, 481 }; 482 483 /** 484 * cmm_count_pages - Count the number of pages loaned in a particular range. 485 * 486 * @arg: memory_isolate_notify structure with address range and count 487 * 488 * Return value: 489 * 0 on success 490 **/ 491 static unsigned long cmm_count_pages(void *arg) 492 { 493 struct memory_isolate_notify *marg = arg; 494 struct cmm_page_array *pa; 495 unsigned long start = (unsigned long)pfn_to_kaddr(marg->start_pfn); 496 unsigned long end = start + (marg->nr_pages << PAGE_SHIFT); 497 unsigned long idx; 498 499 spin_lock(&cmm_lock); 500 pa = cmm_page_list; 501 while (pa) { 502 if ((unsigned long)pa >= start && (unsigned long)pa < end) 503 marg->pages_found++; 504 for (idx = 0; idx < pa->index; idx++) 505 if (pa->page[idx] >= start && pa->page[idx] < end) 506 marg->pages_found++; 507 pa = pa->next; 508 } 509 spin_unlock(&cmm_lock); 510 return 0; 511 } 512 513 /** 514 * cmm_memory_isolate_cb - Handle memory isolation notifier calls 515 * @self: notifier block struct 516 * @action: action to take 517 * @arg: struct memory_isolate_notify data for handler 518 * 519 * Return value: 520 * NOTIFY_OK or notifier error based on subfunction return value 521 **/ 522 static int cmm_memory_isolate_cb(struct notifier_block *self, 523 unsigned long action, void *arg) 524 { 525 int ret = 0; 526 527 if (action == MEM_ISOLATE_COUNT) 528 ret = cmm_count_pages(arg); 529 530 return notifier_from_errno(ret); 531 } 532 533 static struct notifier_block cmm_mem_isolate_nb = { 534 .notifier_call = cmm_memory_isolate_cb, 535 .priority = CMM_MEM_ISOLATE_PRI 536 }; 537 538 /** 539 * cmm_mem_going_offline - Unloan pages where memory is to be removed 540 * @arg: memory_notify structure with page range to be offlined 541 * 542 * Return value: 543 * 0 on success 544 **/ 545 static int cmm_mem_going_offline(void *arg) 546 { 547 struct memory_notify *marg = arg; 548 unsigned long start_page = (unsigned long)pfn_to_kaddr(marg->start_pfn); 549 unsigned long end_page = start_page + (marg->nr_pages << PAGE_SHIFT); 550 struct cmm_page_array *pa_curr, *pa_last, *npa; 551 unsigned long idx; 552 unsigned long freed = 0; 553 554 cmm_dbg("Memory going offline, searching 0x%lx (%ld pages).\n", 555 start_page, marg->nr_pages); 556 spin_lock(&cmm_lock); 557 558 /* Search the page list for pages in the range to be offlined */ 559 pa_last = pa_curr = cmm_page_list; 560 while (pa_curr) { 561 for (idx = (pa_curr->index - 1); (idx + 1) > 0; idx--) { 562 if ((pa_curr->page[idx] < start_page) || 563 (pa_curr->page[idx] >= end_page)) 564 continue; 565 566 plpar_page_set_active(__pa(pa_curr->page[idx])); 567 free_page(pa_curr->page[idx]); 568 freed++; 569 loaned_pages--; 570 totalram_pages_inc(); 571 pa_curr->page[idx] = pa_last->page[--pa_last->index]; 572 if (pa_last->index == 0) { 573 if (pa_curr == pa_last) 574 pa_curr = pa_last->next; 575 pa_last = pa_last->next; 576 free_page((unsigned long)cmm_page_list); 577 cmm_page_list = pa_last; 578 } 579 } 580 pa_curr = pa_curr->next; 581 } 582 583 /* Search for page list structures in the range to be offlined */ 584 pa_last = NULL; 585 pa_curr = cmm_page_list; 586 while (pa_curr) { 587 if (((unsigned long)pa_curr >= start_page) && 588 ((unsigned long)pa_curr < end_page)) { 589 npa = (struct cmm_page_array *)__get_free_page( 590 GFP_NOIO | __GFP_NOWARN | 591 __GFP_NORETRY | __GFP_NOMEMALLOC); 592 if (!npa) { 593 spin_unlock(&cmm_lock); 594 cmm_dbg("Failed to allocate memory for list " 595 "management. Memory hotplug " 596 "failed.\n"); 597 return -ENOMEM; 598 } 599 memcpy(npa, pa_curr, PAGE_SIZE); 600 if (pa_curr == cmm_page_list) 601 cmm_page_list = npa; 602 if (pa_last) 603 pa_last->next = npa; 604 free_page((unsigned long) pa_curr); 605 freed++; 606 pa_curr = npa; 607 } 608 609 pa_last = pa_curr; 610 pa_curr = pa_curr->next; 611 } 612 613 spin_unlock(&cmm_lock); 614 cmm_dbg("Released %ld pages in the search range.\n", freed); 615 616 return 0; 617 } 618 619 /** 620 * cmm_memory_cb - Handle memory hotplug notifier calls 621 * @self: notifier block struct 622 * @action: action to take 623 * @arg: struct memory_notify data for handler 624 * 625 * Return value: 626 * NOTIFY_OK or notifier error based on subfunction return value 627 * 628 **/ 629 static int cmm_memory_cb(struct notifier_block *self, 630 unsigned long action, void *arg) 631 { 632 int ret = 0; 633 634 switch (action) { 635 case MEM_GOING_OFFLINE: 636 mutex_lock(&hotplug_mutex); 637 hotplug_occurred = 1; 638 ret = cmm_mem_going_offline(arg); 639 break; 640 case MEM_OFFLINE: 641 case MEM_CANCEL_OFFLINE: 642 mutex_unlock(&hotplug_mutex); 643 cmm_dbg("Memory offline operation complete.\n"); 644 break; 645 case MEM_GOING_ONLINE: 646 case MEM_ONLINE: 647 case MEM_CANCEL_ONLINE: 648 break; 649 } 650 651 return notifier_from_errno(ret); 652 } 653 654 static struct notifier_block cmm_mem_nb = { 655 .notifier_call = cmm_memory_cb, 656 .priority = CMM_MEM_HOTPLUG_PRI 657 }; 658 659 /** 660 * cmm_init - Module initialization 661 * 662 * Return value: 663 * 0 on success / other on failure 664 **/ 665 static int cmm_init(void) 666 { 667 int rc = -ENOMEM; 668 669 if (!firmware_has_feature(FW_FEATURE_CMO)) 670 return -EOPNOTSUPP; 671 672 if ((rc = register_oom_notifier(&cmm_oom_nb)) < 0) 673 return rc; 674 675 if ((rc = register_reboot_notifier(&cmm_reboot_nb))) 676 goto out_oom_notifier; 677 678 if ((rc = cmm_sysfs_register(&cmm_dev))) 679 goto out_reboot_notifier; 680 681 if (register_memory_notifier(&cmm_mem_nb) || 682 register_memory_isolate_notifier(&cmm_mem_isolate_nb)) 683 goto out_unregister_notifier; 684 685 if (cmm_disabled) 686 return rc; 687 688 cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread"); 689 if (IS_ERR(cmm_thread_ptr)) { 690 rc = PTR_ERR(cmm_thread_ptr); 691 goto out_unregister_notifier; 692 } 693 694 return rc; 695 696 out_unregister_notifier: 697 unregister_memory_notifier(&cmm_mem_nb); 698 unregister_memory_isolate_notifier(&cmm_mem_isolate_nb); 699 cmm_unregister_sysfs(&cmm_dev); 700 out_reboot_notifier: 701 unregister_reboot_notifier(&cmm_reboot_nb); 702 out_oom_notifier: 703 unregister_oom_notifier(&cmm_oom_nb); 704 return rc; 705 } 706 707 /** 708 * cmm_exit - Module exit 709 * 710 * Return value: 711 * nothing 712 **/ 713 static void cmm_exit(void) 714 { 715 if (cmm_thread_ptr) 716 kthread_stop(cmm_thread_ptr); 717 unregister_oom_notifier(&cmm_oom_nb); 718 unregister_reboot_notifier(&cmm_reboot_nb); 719 unregister_memory_notifier(&cmm_mem_nb); 720 unregister_memory_isolate_notifier(&cmm_mem_isolate_nb); 721 cmm_free_pages(loaned_pages); 722 cmm_unregister_sysfs(&cmm_dev); 723 } 724 725 /** 726 * cmm_set_disable - Disable/Enable CMM 727 * 728 * Return value: 729 * 0 on success / other on failure 730 **/ 731 static int cmm_set_disable(const char *val, const struct kernel_param *kp) 732 { 733 int disable = simple_strtoul(val, NULL, 10); 734 735 if (disable != 0 && disable != 1) 736 return -EINVAL; 737 738 if (disable && !cmm_disabled) { 739 if (cmm_thread_ptr) 740 kthread_stop(cmm_thread_ptr); 741 cmm_thread_ptr = NULL; 742 cmm_free_pages(loaned_pages); 743 } else if (!disable && cmm_disabled) { 744 cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread"); 745 if (IS_ERR(cmm_thread_ptr)) 746 return PTR_ERR(cmm_thread_ptr); 747 } 748 749 cmm_disabled = disable; 750 return 0; 751 } 752 753 module_param_call(disable, cmm_set_disable, param_get_uint, 754 &cmm_disabled, 0644); 755 MODULE_PARM_DESC(disable, "Disable CMM. Set to 1 to disable. " 756 "[Default=" __stringify(CMM_DISABLE) "]"); 757 758 module_init(cmm_init); 759 module_exit(cmm_exit); 760