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/kthread.h> 29 #include <linux/module.h> 30 #include <linux/oom.h> 31 #include <linux/reboot.h> 32 #include <linux/sched.h> 33 #include <linux/stringify.h> 34 #include <linux/swap.h> 35 #include <linux/device.h> 36 #include <asm/firmware.h> 37 #include <asm/hvcall.h> 38 #include <asm/mmu.h> 39 #include <asm/pgalloc.h> 40 #include <linux/uaccess.h> 41 #include <linux/memory.h> 42 #include <asm/plpar_wrappers.h> 43 44 #include "pseries.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(hotplug_delay, "Delay (in seconds) after memory hotplug remove " 80 "before loaning resumes. " 81 "[Default=" __stringify(CMM_HOTPLUG_DELAY) "]"); 82 module_param_named(oom_kb, oom_kb, uint, 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 static long plpar_page_set_loaned(unsigned long vpa) 115 { 116 unsigned long cmo_page_sz = cmo_get_page_size(); 117 long rc = 0; 118 int i; 119 120 for (i = 0; !rc && i < PAGE_SIZE; i += cmo_page_sz) 121 rc = plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_LOANED, vpa + i, 0); 122 123 for (i -= cmo_page_sz; rc && i != 0; i -= cmo_page_sz) 124 plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_ACTIVE, 125 vpa + i - cmo_page_sz, 0); 126 127 return rc; 128 } 129 130 static long plpar_page_set_active(unsigned long vpa) 131 { 132 unsigned long cmo_page_sz = cmo_get_page_size(); 133 long rc = 0; 134 int i; 135 136 for (i = 0; !rc && i < PAGE_SIZE; i += cmo_page_sz) 137 rc = plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_ACTIVE, vpa + i, 0); 138 139 for (i -= cmo_page_sz; rc && i != 0; i -= cmo_page_sz) 140 plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_LOANED, 141 vpa + i - cmo_page_sz, 0); 142 143 return rc; 144 } 145 146 /** 147 * cmm_alloc_pages - Allocate pages and mark them as loaned 148 * @nr: number of pages to allocate 149 * 150 * Return value: 151 * number of pages requested to be allocated which were not 152 **/ 153 static long cmm_alloc_pages(long nr) 154 { 155 struct cmm_page_array *pa, *npa; 156 unsigned long addr; 157 long rc; 158 159 cmm_dbg("Begin request for %ld pages\n", nr); 160 161 while (nr) { 162 /* Exit if a hotplug operation is in progress or occurred */ 163 if (mutex_trylock(&hotplug_mutex)) { 164 if (hotplug_occurred) { 165 mutex_unlock(&hotplug_mutex); 166 break; 167 } 168 mutex_unlock(&hotplug_mutex); 169 } else { 170 break; 171 } 172 173 addr = __get_free_page(GFP_NOIO | __GFP_NOWARN | 174 __GFP_NORETRY | __GFP_NOMEMALLOC); 175 if (!addr) 176 break; 177 spin_lock(&cmm_lock); 178 pa = cmm_page_list; 179 if (!pa || pa->index >= CMM_NR_PAGES) { 180 /* Need a new page for the page list. */ 181 spin_unlock(&cmm_lock); 182 npa = (struct cmm_page_array *)__get_free_page( 183 GFP_NOIO | __GFP_NOWARN | 184 __GFP_NORETRY | __GFP_NOMEMALLOC); 185 if (!npa) { 186 pr_info("%s: Can not allocate new page list\n", __func__); 187 free_page(addr); 188 break; 189 } 190 spin_lock(&cmm_lock); 191 pa = cmm_page_list; 192 193 if (!pa || pa->index >= CMM_NR_PAGES) { 194 npa->next = pa; 195 npa->index = 0; 196 pa = npa; 197 cmm_page_list = pa; 198 } else 199 free_page((unsigned long) npa); 200 } 201 202 if ((rc = plpar_page_set_loaned(__pa(addr)))) { 203 pr_err("%s: Can not set page to loaned. rc=%ld\n", __func__, rc); 204 spin_unlock(&cmm_lock); 205 free_page(addr); 206 break; 207 } 208 209 pa->page[pa->index++] = addr; 210 loaned_pages++; 211 totalram_pages--; 212 spin_unlock(&cmm_lock); 213 nr--; 214 } 215 216 cmm_dbg("End request with %ld pages unfulfilled\n", nr); 217 return nr; 218 } 219 220 /** 221 * cmm_free_pages - Free pages and mark them as active 222 * @nr: number of pages to free 223 * 224 * Return value: 225 * number of pages requested to be freed which were not 226 **/ 227 static long cmm_free_pages(long nr) 228 { 229 struct cmm_page_array *pa; 230 unsigned long addr; 231 232 cmm_dbg("Begin free of %ld pages.\n", nr); 233 spin_lock(&cmm_lock); 234 pa = cmm_page_list; 235 while (nr) { 236 if (!pa || pa->index <= 0) 237 break; 238 addr = pa->page[--pa->index]; 239 240 if (pa->index == 0) { 241 pa = pa->next; 242 free_page((unsigned long) cmm_page_list); 243 cmm_page_list = pa; 244 } 245 246 plpar_page_set_active(__pa(addr)); 247 free_page(addr); 248 loaned_pages--; 249 nr--; 250 totalram_pages++; 251 } 252 spin_unlock(&cmm_lock); 253 cmm_dbg("End request with %ld pages unfulfilled\n", nr); 254 return nr; 255 } 256 257 /** 258 * cmm_oom_notify - OOM notifier 259 * @self: notifier block struct 260 * @dummy: not used 261 * @parm: returned - number of pages freed 262 * 263 * Return value: 264 * NOTIFY_OK 265 **/ 266 static int cmm_oom_notify(struct notifier_block *self, 267 unsigned long dummy, void *parm) 268 { 269 unsigned long *freed = parm; 270 long nr = KB2PAGES(oom_kb); 271 272 cmm_dbg("OOM processing started\n"); 273 nr = cmm_free_pages(nr); 274 loaned_pages_target = loaned_pages; 275 *freed += KB2PAGES(oom_kb) - nr; 276 oom_freed_pages += KB2PAGES(oom_kb) - nr; 277 cmm_dbg("OOM processing complete\n"); 278 return NOTIFY_OK; 279 } 280 281 /** 282 * cmm_get_mpp - Read memory performance parameters 283 * 284 * Makes hcall to query the current page loan request from the hypervisor. 285 * 286 * Return value: 287 * nothing 288 **/ 289 static void cmm_get_mpp(void) 290 { 291 int rc; 292 struct hvcall_mpp_data mpp_data; 293 signed long active_pages_target, page_loan_request, target; 294 signed long total_pages = totalram_pages + loaned_pages; 295 signed long min_mem_pages = (min_mem_mb * 1024 * 1024) / PAGE_SIZE; 296 297 rc = h_get_mpp(&mpp_data); 298 299 if (rc != H_SUCCESS) 300 return; 301 302 page_loan_request = div_s64((s64)mpp_data.loan_request, PAGE_SIZE); 303 target = page_loan_request + (signed long)loaned_pages; 304 305 if (target < 0 || total_pages < min_mem_pages) 306 target = 0; 307 308 if (target > oom_freed_pages) 309 target -= oom_freed_pages; 310 else 311 target = 0; 312 313 active_pages_target = total_pages - target; 314 315 if (min_mem_pages > active_pages_target) 316 target = total_pages - min_mem_pages; 317 318 if (target < 0) 319 target = 0; 320 321 loaned_pages_target = target; 322 323 cmm_dbg("delta = %ld, loaned = %lu, target = %lu, oom = %lu, totalram = %lu\n", 324 page_loan_request, loaned_pages, loaned_pages_target, 325 oom_freed_pages, totalram_pages); 326 } 327 328 static struct notifier_block cmm_oom_nb = { 329 .notifier_call = cmm_oom_notify 330 }; 331 332 /** 333 * cmm_thread - CMM task thread 334 * @dummy: not used 335 * 336 * Return value: 337 * 0 338 **/ 339 static int cmm_thread(void *dummy) 340 { 341 unsigned long timeleft; 342 343 while (1) { 344 timeleft = msleep_interruptible(delay * 1000); 345 346 if (kthread_should_stop() || timeleft) 347 break; 348 349 if (mutex_trylock(&hotplug_mutex)) { 350 if (hotplug_occurred) { 351 hotplug_occurred = 0; 352 mutex_unlock(&hotplug_mutex); 353 cmm_dbg("Hotplug operation has occurred, " 354 "loaning activity suspended " 355 "for %d seconds.\n", 356 hotplug_delay); 357 timeleft = msleep_interruptible(hotplug_delay * 358 1000); 359 if (kthread_should_stop() || timeleft) 360 break; 361 continue; 362 } 363 mutex_unlock(&hotplug_mutex); 364 } else { 365 cmm_dbg("Hotplug operation in progress, activity " 366 "suspended\n"); 367 continue; 368 } 369 370 cmm_get_mpp(); 371 372 if (loaned_pages_target > loaned_pages) { 373 if (cmm_alloc_pages(loaned_pages_target - loaned_pages)) 374 loaned_pages_target = loaned_pages; 375 } else if (loaned_pages_target < loaned_pages) 376 cmm_free_pages(loaned_pages - loaned_pages_target); 377 } 378 return 0; 379 } 380 381 #define CMM_SHOW(name, format, args...) \ 382 static ssize_t show_##name(struct device *dev, \ 383 struct device_attribute *attr, \ 384 char *buf) \ 385 { \ 386 return sprintf(buf, format, ##args); \ 387 } \ 388 static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL) 389 390 CMM_SHOW(loaned_kb, "%lu\n", PAGES2KB(loaned_pages)); 391 CMM_SHOW(loaned_target_kb, "%lu\n", PAGES2KB(loaned_pages_target)); 392 393 static ssize_t show_oom_pages(struct device *dev, 394 struct device_attribute *attr, char *buf) 395 { 396 return sprintf(buf, "%lu\n", PAGES2KB(oom_freed_pages)); 397 } 398 399 static ssize_t store_oom_pages(struct device *dev, 400 struct device_attribute *attr, 401 const char *buf, size_t count) 402 { 403 unsigned long val = simple_strtoul (buf, NULL, 10); 404 405 if (!capable(CAP_SYS_ADMIN)) 406 return -EPERM; 407 if (val != 0) 408 return -EBADMSG; 409 410 oom_freed_pages = 0; 411 return count; 412 } 413 414 static DEVICE_ATTR(oom_freed_kb, S_IWUSR | S_IRUGO, 415 show_oom_pages, store_oom_pages); 416 417 static struct device_attribute *cmm_attrs[] = { 418 &dev_attr_loaned_kb, 419 &dev_attr_loaned_target_kb, 420 &dev_attr_oom_freed_kb, 421 }; 422 423 static struct bus_type cmm_subsys = { 424 .name = "cmm", 425 .dev_name = "cmm", 426 }; 427 428 /** 429 * cmm_sysfs_register - Register with sysfs 430 * 431 * Return value: 432 * 0 on success / other on failure 433 **/ 434 static int cmm_sysfs_register(struct device *dev) 435 { 436 int i, rc; 437 438 if ((rc = subsys_system_register(&cmm_subsys, NULL))) 439 return rc; 440 441 dev->id = 0; 442 dev->bus = &cmm_subsys; 443 444 if ((rc = device_register(dev))) 445 goto subsys_unregister; 446 447 for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++) { 448 if ((rc = device_create_file(dev, cmm_attrs[i]))) 449 goto fail; 450 } 451 452 return 0; 453 454 fail: 455 while (--i >= 0) 456 device_remove_file(dev, cmm_attrs[i]); 457 device_unregister(dev); 458 subsys_unregister: 459 bus_unregister(&cmm_subsys); 460 return rc; 461 } 462 463 /** 464 * cmm_unregister_sysfs - Unregister from sysfs 465 * 466 **/ 467 static void cmm_unregister_sysfs(struct device *dev) 468 { 469 int i; 470 471 for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++) 472 device_remove_file(dev, cmm_attrs[i]); 473 device_unregister(dev); 474 bus_unregister(&cmm_subsys); 475 } 476 477 /** 478 * cmm_reboot_notifier - Make sure pages are not still marked as "loaned" 479 * 480 **/ 481 static int cmm_reboot_notifier(struct notifier_block *nb, 482 unsigned long action, void *unused) 483 { 484 if (action == SYS_RESTART) { 485 if (cmm_thread_ptr) 486 kthread_stop(cmm_thread_ptr); 487 cmm_thread_ptr = NULL; 488 cmm_free_pages(loaned_pages); 489 } 490 return NOTIFY_DONE; 491 } 492 493 static struct notifier_block cmm_reboot_nb = { 494 .notifier_call = cmm_reboot_notifier, 495 }; 496 497 /** 498 * cmm_count_pages - Count the number of pages loaned in a particular range. 499 * 500 * @arg: memory_isolate_notify structure with address range and count 501 * 502 * Return value: 503 * 0 on success 504 **/ 505 static unsigned long cmm_count_pages(void *arg) 506 { 507 struct memory_isolate_notify *marg = arg; 508 struct cmm_page_array *pa; 509 unsigned long start = (unsigned long)pfn_to_kaddr(marg->start_pfn); 510 unsigned long end = start + (marg->nr_pages << PAGE_SHIFT); 511 unsigned long idx; 512 513 spin_lock(&cmm_lock); 514 pa = cmm_page_list; 515 while (pa) { 516 if ((unsigned long)pa >= start && (unsigned long)pa < end) 517 marg->pages_found++; 518 for (idx = 0; idx < pa->index; idx++) 519 if (pa->page[idx] >= start && pa->page[idx] < end) 520 marg->pages_found++; 521 pa = pa->next; 522 } 523 spin_unlock(&cmm_lock); 524 return 0; 525 } 526 527 /** 528 * cmm_memory_isolate_cb - Handle memory isolation notifier calls 529 * @self: notifier block struct 530 * @action: action to take 531 * @arg: struct memory_isolate_notify data for handler 532 * 533 * Return value: 534 * NOTIFY_OK or notifier error based on subfunction return value 535 **/ 536 static int cmm_memory_isolate_cb(struct notifier_block *self, 537 unsigned long action, void *arg) 538 { 539 int ret = 0; 540 541 if (action == MEM_ISOLATE_COUNT) 542 ret = cmm_count_pages(arg); 543 544 return notifier_from_errno(ret); 545 } 546 547 static struct notifier_block cmm_mem_isolate_nb = { 548 .notifier_call = cmm_memory_isolate_cb, 549 .priority = CMM_MEM_ISOLATE_PRI 550 }; 551 552 /** 553 * cmm_mem_going_offline - Unloan pages where memory is to be removed 554 * @arg: memory_notify structure with page range to be offlined 555 * 556 * Return value: 557 * 0 on success 558 **/ 559 static int cmm_mem_going_offline(void *arg) 560 { 561 struct memory_notify *marg = arg; 562 unsigned long start_page = (unsigned long)pfn_to_kaddr(marg->start_pfn); 563 unsigned long end_page = start_page + (marg->nr_pages << PAGE_SHIFT); 564 struct cmm_page_array *pa_curr, *pa_last, *npa; 565 unsigned long idx; 566 unsigned long freed = 0; 567 568 cmm_dbg("Memory going offline, searching 0x%lx (%ld pages).\n", 569 start_page, marg->nr_pages); 570 spin_lock(&cmm_lock); 571 572 /* Search the page list for pages in the range to be offlined */ 573 pa_last = pa_curr = cmm_page_list; 574 while (pa_curr) { 575 for (idx = (pa_curr->index - 1); (idx + 1) > 0; idx--) { 576 if ((pa_curr->page[idx] < start_page) || 577 (pa_curr->page[idx] >= end_page)) 578 continue; 579 580 plpar_page_set_active(__pa(pa_curr->page[idx])); 581 free_page(pa_curr->page[idx]); 582 freed++; 583 loaned_pages--; 584 totalram_pages++; 585 pa_curr->page[idx] = pa_last->page[--pa_last->index]; 586 if (pa_last->index == 0) { 587 if (pa_curr == pa_last) 588 pa_curr = pa_last->next; 589 pa_last = pa_last->next; 590 free_page((unsigned long)cmm_page_list); 591 cmm_page_list = pa_last; 592 } 593 } 594 pa_curr = pa_curr->next; 595 } 596 597 /* Search for page list structures in the range to be offlined */ 598 pa_last = NULL; 599 pa_curr = cmm_page_list; 600 while (pa_curr) { 601 if (((unsigned long)pa_curr >= start_page) && 602 ((unsigned long)pa_curr < end_page)) { 603 npa = (struct cmm_page_array *)__get_free_page( 604 GFP_NOIO | __GFP_NOWARN | 605 __GFP_NORETRY | __GFP_NOMEMALLOC); 606 if (!npa) { 607 spin_unlock(&cmm_lock); 608 cmm_dbg("Failed to allocate memory for list " 609 "management. Memory hotplug " 610 "failed.\n"); 611 return -ENOMEM; 612 } 613 memcpy(npa, pa_curr, PAGE_SIZE); 614 if (pa_curr == cmm_page_list) 615 cmm_page_list = npa; 616 if (pa_last) 617 pa_last->next = npa; 618 free_page((unsigned long) pa_curr); 619 freed++; 620 pa_curr = npa; 621 } 622 623 pa_last = pa_curr; 624 pa_curr = pa_curr->next; 625 } 626 627 spin_unlock(&cmm_lock); 628 cmm_dbg("Released %ld pages in the search range.\n", freed); 629 630 return 0; 631 } 632 633 /** 634 * cmm_memory_cb - Handle memory hotplug notifier calls 635 * @self: notifier block struct 636 * @action: action to take 637 * @arg: struct memory_notify data for handler 638 * 639 * Return value: 640 * NOTIFY_OK or notifier error based on subfunction return value 641 * 642 **/ 643 static int cmm_memory_cb(struct notifier_block *self, 644 unsigned long action, void *arg) 645 { 646 int ret = 0; 647 648 switch (action) { 649 case MEM_GOING_OFFLINE: 650 mutex_lock(&hotplug_mutex); 651 hotplug_occurred = 1; 652 ret = cmm_mem_going_offline(arg); 653 break; 654 case MEM_OFFLINE: 655 case MEM_CANCEL_OFFLINE: 656 mutex_unlock(&hotplug_mutex); 657 cmm_dbg("Memory offline operation complete.\n"); 658 break; 659 case MEM_GOING_ONLINE: 660 case MEM_ONLINE: 661 case MEM_CANCEL_ONLINE: 662 break; 663 } 664 665 return notifier_from_errno(ret); 666 } 667 668 static struct notifier_block cmm_mem_nb = { 669 .notifier_call = cmm_memory_cb, 670 .priority = CMM_MEM_HOTPLUG_PRI 671 }; 672 673 /** 674 * cmm_init - Module initialization 675 * 676 * Return value: 677 * 0 on success / other on failure 678 **/ 679 static int cmm_init(void) 680 { 681 int rc = -ENOMEM; 682 683 if (!firmware_has_feature(FW_FEATURE_CMO)) 684 return -EOPNOTSUPP; 685 686 if ((rc = register_oom_notifier(&cmm_oom_nb)) < 0) 687 return rc; 688 689 if ((rc = register_reboot_notifier(&cmm_reboot_nb))) 690 goto out_oom_notifier; 691 692 if ((rc = cmm_sysfs_register(&cmm_dev))) 693 goto out_reboot_notifier; 694 695 if (register_memory_notifier(&cmm_mem_nb) || 696 register_memory_isolate_notifier(&cmm_mem_isolate_nb)) 697 goto out_unregister_notifier; 698 699 if (cmm_disabled) 700 return rc; 701 702 cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread"); 703 if (IS_ERR(cmm_thread_ptr)) { 704 rc = PTR_ERR(cmm_thread_ptr); 705 goto out_unregister_notifier; 706 } 707 708 return rc; 709 710 out_unregister_notifier: 711 unregister_memory_notifier(&cmm_mem_nb); 712 unregister_memory_isolate_notifier(&cmm_mem_isolate_nb); 713 cmm_unregister_sysfs(&cmm_dev); 714 out_reboot_notifier: 715 unregister_reboot_notifier(&cmm_reboot_nb); 716 out_oom_notifier: 717 unregister_oom_notifier(&cmm_oom_nb); 718 return rc; 719 } 720 721 /** 722 * cmm_exit - Module exit 723 * 724 * Return value: 725 * nothing 726 **/ 727 static void cmm_exit(void) 728 { 729 if (cmm_thread_ptr) 730 kthread_stop(cmm_thread_ptr); 731 unregister_oom_notifier(&cmm_oom_nb); 732 unregister_reboot_notifier(&cmm_reboot_nb); 733 unregister_memory_notifier(&cmm_mem_nb); 734 unregister_memory_isolate_notifier(&cmm_mem_isolate_nb); 735 cmm_free_pages(loaned_pages); 736 cmm_unregister_sysfs(&cmm_dev); 737 } 738 739 /** 740 * cmm_set_disable - Disable/Enable CMM 741 * 742 * Return value: 743 * 0 on success / other on failure 744 **/ 745 static int cmm_set_disable(const char *val, struct kernel_param *kp) 746 { 747 int disable = simple_strtoul(val, NULL, 10); 748 749 if (disable != 0 && disable != 1) 750 return -EINVAL; 751 752 if (disable && !cmm_disabled) { 753 if (cmm_thread_ptr) 754 kthread_stop(cmm_thread_ptr); 755 cmm_thread_ptr = NULL; 756 cmm_free_pages(loaned_pages); 757 } else if (!disable && cmm_disabled) { 758 cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread"); 759 if (IS_ERR(cmm_thread_ptr)) 760 return PTR_ERR(cmm_thread_ptr); 761 } 762 763 cmm_disabled = disable; 764 return 0; 765 } 766 767 module_param_call(disable, cmm_set_disable, param_get_uint, 768 &cmm_disabled, S_IRUGO | S_IWUSR); 769 MODULE_PARM_DESC(disable, "Disable CMM. Set to 1 to disable. " 770 "[Default=" __stringify(CMM_DISABLE) "]"); 771 772 module_init(cmm_init); 773 module_exit(cmm_exit); 774