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