1 /* 2 * kernel/cpuset.c 3 * 4 * Processor and Memory placement constraints for sets of tasks. 5 * 6 * Copyright (C) 2003 BULL SA. 7 * Copyright (C) 2004-2007 Silicon Graphics, Inc. 8 * Copyright (C) 2006 Google, Inc 9 * 10 * Portions derived from Patrick Mochel's sysfs code. 11 * sysfs is Copyright (c) 2001-3 Patrick Mochel 12 * 13 * 2003-10-10 Written by Simon Derr. 14 * 2003-10-22 Updates by Stephen Hemminger. 15 * 2004 May-July Rework by Paul Jackson. 16 * 2006 Rework by Paul Menage to use generic cgroups 17 * 2008 Rework of the scheduler domains and CPU hotplug handling 18 * by Max Krasnyansky 19 * 20 * This file is subject to the terms and conditions of the GNU General Public 21 * License. See the file COPYING in the main directory of the Linux 22 * distribution for more details. 23 */ 24 25 #include <linux/cpu.h> 26 #include <linux/cpumask.h> 27 #include <linux/cpuset.h> 28 #include <linux/err.h> 29 #include <linux/errno.h> 30 #include <linux/file.h> 31 #include <linux/fs.h> 32 #include <linux/init.h> 33 #include <linux/interrupt.h> 34 #include <linux/kernel.h> 35 #include <linux/kmod.h> 36 #include <linux/list.h> 37 #include <linux/mempolicy.h> 38 #include <linux/mm.h> 39 #include <linux/memory.h> 40 #include <linux/export.h> 41 #include <linux/mount.h> 42 #include <linux/namei.h> 43 #include <linux/pagemap.h> 44 #include <linux/proc_fs.h> 45 #include <linux/rcupdate.h> 46 #include <linux/sched.h> 47 #include <linux/sched/mm.h> 48 #include <linux/sched/task.h> 49 #include <linux/seq_file.h> 50 #include <linux/security.h> 51 #include <linux/slab.h> 52 #include <linux/spinlock.h> 53 #include <linux/stat.h> 54 #include <linux/string.h> 55 #include <linux/time.h> 56 #include <linux/time64.h> 57 #include <linux/backing-dev.h> 58 #include <linux/sort.h> 59 60 #include <linux/uaccess.h> 61 #include <linux/atomic.h> 62 #include <linux/mutex.h> 63 #include <linux/cgroup.h> 64 #include <linux/wait.h> 65 66 DEFINE_STATIC_KEY_FALSE(cpusets_pre_enable_key); 67 DEFINE_STATIC_KEY_FALSE(cpusets_enabled_key); 68 69 /* See "Frequency meter" comments, below. */ 70 71 struct fmeter { 72 int cnt; /* unprocessed events count */ 73 int val; /* most recent output value */ 74 time64_t time; /* clock (secs) when val computed */ 75 spinlock_t lock; /* guards read or write of above */ 76 }; 77 78 struct cpuset { 79 struct cgroup_subsys_state css; 80 81 unsigned long flags; /* "unsigned long" so bitops work */ 82 83 /* 84 * On default hierarchy: 85 * 86 * The user-configured masks can only be changed by writing to 87 * cpuset.cpus and cpuset.mems, and won't be limited by the 88 * parent masks. 89 * 90 * The effective masks is the real masks that apply to the tasks 91 * in the cpuset. They may be changed if the configured masks are 92 * changed or hotplug happens. 93 * 94 * effective_mask == configured_mask & parent's effective_mask, 95 * and if it ends up empty, it will inherit the parent's mask. 96 * 97 * 98 * On legacy hierachy: 99 * 100 * The user-configured masks are always the same with effective masks. 101 */ 102 103 /* user-configured CPUs and Memory Nodes allow to tasks */ 104 cpumask_var_t cpus_allowed; 105 nodemask_t mems_allowed; 106 107 /* effective CPUs and Memory Nodes allow to tasks */ 108 cpumask_var_t effective_cpus; 109 nodemask_t effective_mems; 110 111 /* 112 * This is old Memory Nodes tasks took on. 113 * 114 * - top_cpuset.old_mems_allowed is initialized to mems_allowed. 115 * - A new cpuset's old_mems_allowed is initialized when some 116 * task is moved into it. 117 * - old_mems_allowed is used in cpuset_migrate_mm() when we change 118 * cpuset.mems_allowed and have tasks' nodemask updated, and 119 * then old_mems_allowed is updated to mems_allowed. 120 */ 121 nodemask_t old_mems_allowed; 122 123 struct fmeter fmeter; /* memory_pressure filter */ 124 125 /* 126 * Tasks are being attached to this cpuset. Used to prevent 127 * zeroing cpus/mems_allowed between ->can_attach() and ->attach(). 128 */ 129 int attach_in_progress; 130 131 /* partition number for rebuild_sched_domains() */ 132 int pn; 133 134 /* for custom sched domain */ 135 int relax_domain_level; 136 }; 137 138 static inline struct cpuset *css_cs(struct cgroup_subsys_state *css) 139 { 140 return css ? container_of(css, struct cpuset, css) : NULL; 141 } 142 143 /* Retrieve the cpuset for a task */ 144 static inline struct cpuset *task_cs(struct task_struct *task) 145 { 146 return css_cs(task_css(task, cpuset_cgrp_id)); 147 } 148 149 static inline struct cpuset *parent_cs(struct cpuset *cs) 150 { 151 return css_cs(cs->css.parent); 152 } 153 154 #ifdef CONFIG_NUMA 155 static inline bool task_has_mempolicy(struct task_struct *task) 156 { 157 return task->mempolicy; 158 } 159 #else 160 static inline bool task_has_mempolicy(struct task_struct *task) 161 { 162 return false; 163 } 164 #endif 165 166 167 /* bits in struct cpuset flags field */ 168 typedef enum { 169 CS_ONLINE, 170 CS_CPU_EXCLUSIVE, 171 CS_MEM_EXCLUSIVE, 172 CS_MEM_HARDWALL, 173 CS_MEMORY_MIGRATE, 174 CS_SCHED_LOAD_BALANCE, 175 CS_SPREAD_PAGE, 176 CS_SPREAD_SLAB, 177 } cpuset_flagbits_t; 178 179 /* convenient tests for these bits */ 180 static inline bool is_cpuset_online(struct cpuset *cs) 181 { 182 return test_bit(CS_ONLINE, &cs->flags) && !css_is_dying(&cs->css); 183 } 184 185 static inline int is_cpu_exclusive(const struct cpuset *cs) 186 { 187 return test_bit(CS_CPU_EXCLUSIVE, &cs->flags); 188 } 189 190 static inline int is_mem_exclusive(const struct cpuset *cs) 191 { 192 return test_bit(CS_MEM_EXCLUSIVE, &cs->flags); 193 } 194 195 static inline int is_mem_hardwall(const struct cpuset *cs) 196 { 197 return test_bit(CS_MEM_HARDWALL, &cs->flags); 198 } 199 200 static inline int is_sched_load_balance(const struct cpuset *cs) 201 { 202 return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags); 203 } 204 205 static inline int is_memory_migrate(const struct cpuset *cs) 206 { 207 return test_bit(CS_MEMORY_MIGRATE, &cs->flags); 208 } 209 210 static inline int is_spread_page(const struct cpuset *cs) 211 { 212 return test_bit(CS_SPREAD_PAGE, &cs->flags); 213 } 214 215 static inline int is_spread_slab(const struct cpuset *cs) 216 { 217 return test_bit(CS_SPREAD_SLAB, &cs->flags); 218 } 219 220 static struct cpuset top_cpuset = { 221 .flags = ((1 << CS_ONLINE) | (1 << CS_CPU_EXCLUSIVE) | 222 (1 << CS_MEM_EXCLUSIVE)), 223 }; 224 225 /** 226 * cpuset_for_each_child - traverse online children of a cpuset 227 * @child_cs: loop cursor pointing to the current child 228 * @pos_css: used for iteration 229 * @parent_cs: target cpuset to walk children of 230 * 231 * Walk @child_cs through the online children of @parent_cs. Must be used 232 * with RCU read locked. 233 */ 234 #define cpuset_for_each_child(child_cs, pos_css, parent_cs) \ 235 css_for_each_child((pos_css), &(parent_cs)->css) \ 236 if (is_cpuset_online(((child_cs) = css_cs((pos_css))))) 237 238 /** 239 * cpuset_for_each_descendant_pre - pre-order walk of a cpuset's descendants 240 * @des_cs: loop cursor pointing to the current descendant 241 * @pos_css: used for iteration 242 * @root_cs: target cpuset to walk ancestor of 243 * 244 * Walk @des_cs through the online descendants of @root_cs. Must be used 245 * with RCU read locked. The caller may modify @pos_css by calling 246 * css_rightmost_descendant() to skip subtree. @root_cs is included in the 247 * iteration and the first node to be visited. 248 */ 249 #define cpuset_for_each_descendant_pre(des_cs, pos_css, root_cs) \ 250 css_for_each_descendant_pre((pos_css), &(root_cs)->css) \ 251 if (is_cpuset_online(((des_cs) = css_cs((pos_css))))) 252 253 /* 254 * There are two global locks guarding cpuset structures - cpuset_mutex and 255 * callback_lock. We also require taking task_lock() when dereferencing a 256 * task's cpuset pointer. See "The task_lock() exception", at the end of this 257 * comment. 258 * 259 * A task must hold both locks to modify cpusets. If a task holds 260 * cpuset_mutex, then it blocks others wanting that mutex, ensuring that it 261 * is the only task able to also acquire callback_lock and be able to 262 * modify cpusets. It can perform various checks on the cpuset structure 263 * first, knowing nothing will change. It can also allocate memory while 264 * just holding cpuset_mutex. While it is performing these checks, various 265 * callback routines can briefly acquire callback_lock to query cpusets. 266 * Once it is ready to make the changes, it takes callback_lock, blocking 267 * everyone else. 268 * 269 * Calls to the kernel memory allocator can not be made while holding 270 * callback_lock, as that would risk double tripping on callback_lock 271 * from one of the callbacks into the cpuset code from within 272 * __alloc_pages(). 273 * 274 * If a task is only holding callback_lock, then it has read-only 275 * access to cpusets. 276 * 277 * Now, the task_struct fields mems_allowed and mempolicy may be changed 278 * by other task, we use alloc_lock in the task_struct fields to protect 279 * them. 280 * 281 * The cpuset_common_file_read() handlers only hold callback_lock across 282 * small pieces of code, such as when reading out possibly multi-word 283 * cpumasks and nodemasks. 284 * 285 * Accessing a task's cpuset should be done in accordance with the 286 * guidelines for accessing subsystem state in kernel/cgroup.c 287 */ 288 289 static DEFINE_MUTEX(cpuset_mutex); 290 static DEFINE_SPINLOCK(callback_lock); 291 292 static struct workqueue_struct *cpuset_migrate_mm_wq; 293 294 /* 295 * CPU / memory hotplug is handled asynchronously. 296 */ 297 static void cpuset_hotplug_workfn(struct work_struct *work); 298 static DECLARE_WORK(cpuset_hotplug_work, cpuset_hotplug_workfn); 299 300 static DECLARE_WAIT_QUEUE_HEAD(cpuset_attach_wq); 301 302 /* 303 * This is ugly, but preserves the userspace API for existing cpuset 304 * users. If someone tries to mount the "cpuset" filesystem, we 305 * silently switch it to mount "cgroup" instead 306 */ 307 static struct dentry *cpuset_mount(struct file_system_type *fs_type, 308 int flags, const char *unused_dev_name, void *data) 309 { 310 struct file_system_type *cgroup_fs = get_fs_type("cgroup"); 311 struct dentry *ret = ERR_PTR(-ENODEV); 312 if (cgroup_fs) { 313 char mountopts[] = 314 "cpuset,noprefix," 315 "release_agent=/sbin/cpuset_release_agent"; 316 ret = cgroup_fs->mount(cgroup_fs, flags, 317 unused_dev_name, mountopts); 318 put_filesystem(cgroup_fs); 319 } 320 return ret; 321 } 322 323 static struct file_system_type cpuset_fs_type = { 324 .name = "cpuset", 325 .mount = cpuset_mount, 326 }; 327 328 /* 329 * Return in pmask the portion of a cpusets's cpus_allowed that 330 * are online. If none are online, walk up the cpuset hierarchy 331 * until we find one that does have some online cpus. 332 * 333 * One way or another, we guarantee to return some non-empty subset 334 * of cpu_online_mask. 335 * 336 * Call with callback_lock or cpuset_mutex held. 337 */ 338 static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask) 339 { 340 while (!cpumask_intersects(cs->effective_cpus, cpu_online_mask)) { 341 cs = parent_cs(cs); 342 if (unlikely(!cs)) { 343 /* 344 * The top cpuset doesn't have any online cpu as a 345 * consequence of a race between cpuset_hotplug_work 346 * and cpu hotplug notifier. But we know the top 347 * cpuset's effective_cpus is on its way to to be 348 * identical to cpu_online_mask. 349 */ 350 cpumask_copy(pmask, cpu_online_mask); 351 return; 352 } 353 } 354 cpumask_and(pmask, cs->effective_cpus, cpu_online_mask); 355 } 356 357 /* 358 * Return in *pmask the portion of a cpusets's mems_allowed that 359 * are online, with memory. If none are online with memory, walk 360 * up the cpuset hierarchy until we find one that does have some 361 * online mems. The top cpuset always has some mems online. 362 * 363 * One way or another, we guarantee to return some non-empty subset 364 * of node_states[N_MEMORY]. 365 * 366 * Call with callback_lock or cpuset_mutex held. 367 */ 368 static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask) 369 { 370 while (!nodes_intersects(cs->effective_mems, node_states[N_MEMORY])) 371 cs = parent_cs(cs); 372 nodes_and(*pmask, cs->effective_mems, node_states[N_MEMORY]); 373 } 374 375 /* 376 * update task's spread flag if cpuset's page/slab spread flag is set 377 * 378 * Call with callback_lock or cpuset_mutex held. 379 */ 380 static void cpuset_update_task_spread_flag(struct cpuset *cs, 381 struct task_struct *tsk) 382 { 383 if (is_spread_page(cs)) 384 task_set_spread_page(tsk); 385 else 386 task_clear_spread_page(tsk); 387 388 if (is_spread_slab(cs)) 389 task_set_spread_slab(tsk); 390 else 391 task_clear_spread_slab(tsk); 392 } 393 394 /* 395 * is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q? 396 * 397 * One cpuset is a subset of another if all its allowed CPUs and 398 * Memory Nodes are a subset of the other, and its exclusive flags 399 * are only set if the other's are set. Call holding cpuset_mutex. 400 */ 401 402 static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q) 403 { 404 return cpumask_subset(p->cpus_allowed, q->cpus_allowed) && 405 nodes_subset(p->mems_allowed, q->mems_allowed) && 406 is_cpu_exclusive(p) <= is_cpu_exclusive(q) && 407 is_mem_exclusive(p) <= is_mem_exclusive(q); 408 } 409 410 /** 411 * alloc_trial_cpuset - allocate a trial cpuset 412 * @cs: the cpuset that the trial cpuset duplicates 413 */ 414 static struct cpuset *alloc_trial_cpuset(struct cpuset *cs) 415 { 416 struct cpuset *trial; 417 418 trial = kmemdup(cs, sizeof(*cs), GFP_KERNEL); 419 if (!trial) 420 return NULL; 421 422 if (!alloc_cpumask_var(&trial->cpus_allowed, GFP_KERNEL)) 423 goto free_cs; 424 if (!alloc_cpumask_var(&trial->effective_cpus, GFP_KERNEL)) 425 goto free_cpus; 426 427 cpumask_copy(trial->cpus_allowed, cs->cpus_allowed); 428 cpumask_copy(trial->effective_cpus, cs->effective_cpus); 429 return trial; 430 431 free_cpus: 432 free_cpumask_var(trial->cpus_allowed); 433 free_cs: 434 kfree(trial); 435 return NULL; 436 } 437 438 /** 439 * free_trial_cpuset - free the trial cpuset 440 * @trial: the trial cpuset to be freed 441 */ 442 static void free_trial_cpuset(struct cpuset *trial) 443 { 444 free_cpumask_var(trial->effective_cpus); 445 free_cpumask_var(trial->cpus_allowed); 446 kfree(trial); 447 } 448 449 /* 450 * validate_change() - Used to validate that any proposed cpuset change 451 * follows the structural rules for cpusets. 452 * 453 * If we replaced the flag and mask values of the current cpuset 454 * (cur) with those values in the trial cpuset (trial), would 455 * our various subset and exclusive rules still be valid? Presumes 456 * cpuset_mutex held. 457 * 458 * 'cur' is the address of an actual, in-use cpuset. Operations 459 * such as list traversal that depend on the actual address of the 460 * cpuset in the list must use cur below, not trial. 461 * 462 * 'trial' is the address of bulk structure copy of cur, with 463 * perhaps one or more of the fields cpus_allowed, mems_allowed, 464 * or flags changed to new, trial values. 465 * 466 * Return 0 if valid, -errno if not. 467 */ 468 469 static int validate_change(struct cpuset *cur, struct cpuset *trial) 470 { 471 struct cgroup_subsys_state *css; 472 struct cpuset *c, *par; 473 int ret; 474 475 rcu_read_lock(); 476 477 /* Each of our child cpusets must be a subset of us */ 478 ret = -EBUSY; 479 cpuset_for_each_child(c, css, cur) 480 if (!is_cpuset_subset(c, trial)) 481 goto out; 482 483 /* Remaining checks don't apply to root cpuset */ 484 ret = 0; 485 if (cur == &top_cpuset) 486 goto out; 487 488 par = parent_cs(cur); 489 490 /* On legacy hiearchy, we must be a subset of our parent cpuset. */ 491 ret = -EACCES; 492 if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) && 493 !is_cpuset_subset(trial, par)) 494 goto out; 495 496 /* 497 * If either I or some sibling (!= me) is exclusive, we can't 498 * overlap 499 */ 500 ret = -EINVAL; 501 cpuset_for_each_child(c, css, par) { 502 if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) && 503 c != cur && 504 cpumask_intersects(trial->cpus_allowed, c->cpus_allowed)) 505 goto out; 506 if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) && 507 c != cur && 508 nodes_intersects(trial->mems_allowed, c->mems_allowed)) 509 goto out; 510 } 511 512 /* 513 * Cpusets with tasks - existing or newly being attached - can't 514 * be changed to have empty cpus_allowed or mems_allowed. 515 */ 516 ret = -ENOSPC; 517 if ((cgroup_is_populated(cur->css.cgroup) || cur->attach_in_progress)) { 518 if (!cpumask_empty(cur->cpus_allowed) && 519 cpumask_empty(trial->cpus_allowed)) 520 goto out; 521 if (!nodes_empty(cur->mems_allowed) && 522 nodes_empty(trial->mems_allowed)) 523 goto out; 524 } 525 526 /* 527 * We can't shrink if we won't have enough room for SCHED_DEADLINE 528 * tasks. 529 */ 530 ret = -EBUSY; 531 if (is_cpu_exclusive(cur) && 532 !cpuset_cpumask_can_shrink(cur->cpus_allowed, 533 trial->cpus_allowed)) 534 goto out; 535 536 ret = 0; 537 out: 538 rcu_read_unlock(); 539 return ret; 540 } 541 542 #ifdef CONFIG_SMP 543 /* 544 * Helper routine for generate_sched_domains(). 545 * Do cpusets a, b have overlapping effective cpus_allowed masks? 546 */ 547 static int cpusets_overlap(struct cpuset *a, struct cpuset *b) 548 { 549 return cpumask_intersects(a->effective_cpus, b->effective_cpus); 550 } 551 552 static void 553 update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c) 554 { 555 if (dattr->relax_domain_level < c->relax_domain_level) 556 dattr->relax_domain_level = c->relax_domain_level; 557 return; 558 } 559 560 static void update_domain_attr_tree(struct sched_domain_attr *dattr, 561 struct cpuset *root_cs) 562 { 563 struct cpuset *cp; 564 struct cgroup_subsys_state *pos_css; 565 566 rcu_read_lock(); 567 cpuset_for_each_descendant_pre(cp, pos_css, root_cs) { 568 /* skip the whole subtree if @cp doesn't have any CPU */ 569 if (cpumask_empty(cp->cpus_allowed)) { 570 pos_css = css_rightmost_descendant(pos_css); 571 continue; 572 } 573 574 if (is_sched_load_balance(cp)) 575 update_domain_attr(dattr, cp); 576 } 577 rcu_read_unlock(); 578 } 579 580 /* 581 * generate_sched_domains() 582 * 583 * This function builds a partial partition of the systems CPUs 584 * A 'partial partition' is a set of non-overlapping subsets whose 585 * union is a subset of that set. 586 * The output of this function needs to be passed to kernel/sched/core.c 587 * partition_sched_domains() routine, which will rebuild the scheduler's 588 * load balancing domains (sched domains) as specified by that partial 589 * partition. 590 * 591 * See "What is sched_load_balance" in Documentation/cgroups/cpusets.txt 592 * for a background explanation of this. 593 * 594 * Does not return errors, on the theory that the callers of this 595 * routine would rather not worry about failures to rebuild sched 596 * domains when operating in the severe memory shortage situations 597 * that could cause allocation failures below. 598 * 599 * Must be called with cpuset_mutex held. 600 * 601 * The three key local variables below are: 602 * q - a linked-list queue of cpuset pointers, used to implement a 603 * top-down scan of all cpusets. This scan loads a pointer 604 * to each cpuset marked is_sched_load_balance into the 605 * array 'csa'. For our purposes, rebuilding the schedulers 606 * sched domains, we can ignore !is_sched_load_balance cpusets. 607 * csa - (for CpuSet Array) Array of pointers to all the cpusets 608 * that need to be load balanced, for convenient iterative 609 * access by the subsequent code that finds the best partition, 610 * i.e the set of domains (subsets) of CPUs such that the 611 * cpus_allowed of every cpuset marked is_sched_load_balance 612 * is a subset of one of these domains, while there are as 613 * many such domains as possible, each as small as possible. 614 * doms - Conversion of 'csa' to an array of cpumasks, for passing to 615 * the kernel/sched/core.c routine partition_sched_domains() in a 616 * convenient format, that can be easily compared to the prior 617 * value to determine what partition elements (sched domains) 618 * were changed (added or removed.) 619 * 620 * Finding the best partition (set of domains): 621 * The triple nested loops below over i, j, k scan over the 622 * load balanced cpusets (using the array of cpuset pointers in 623 * csa[]) looking for pairs of cpusets that have overlapping 624 * cpus_allowed, but which don't have the same 'pn' partition 625 * number and gives them in the same partition number. It keeps 626 * looping on the 'restart' label until it can no longer find 627 * any such pairs. 628 * 629 * The union of the cpus_allowed masks from the set of 630 * all cpusets having the same 'pn' value then form the one 631 * element of the partition (one sched domain) to be passed to 632 * partition_sched_domains(). 633 */ 634 static int generate_sched_domains(cpumask_var_t **domains, 635 struct sched_domain_attr **attributes) 636 { 637 struct cpuset *cp; /* scans q */ 638 struct cpuset **csa; /* array of all cpuset ptrs */ 639 int csn; /* how many cpuset ptrs in csa so far */ 640 int i, j, k; /* indices for partition finding loops */ 641 cpumask_var_t *doms; /* resulting partition; i.e. sched domains */ 642 cpumask_var_t non_isolated_cpus; /* load balanced CPUs */ 643 struct sched_domain_attr *dattr; /* attributes for custom domains */ 644 int ndoms = 0; /* number of sched domains in result */ 645 int nslot; /* next empty doms[] struct cpumask slot */ 646 struct cgroup_subsys_state *pos_css; 647 648 doms = NULL; 649 dattr = NULL; 650 csa = NULL; 651 652 if (!alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL)) 653 goto done; 654 cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map); 655 656 /* Special case for the 99% of systems with one, full, sched domain */ 657 if (is_sched_load_balance(&top_cpuset)) { 658 ndoms = 1; 659 doms = alloc_sched_domains(ndoms); 660 if (!doms) 661 goto done; 662 663 dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL); 664 if (dattr) { 665 *dattr = SD_ATTR_INIT; 666 update_domain_attr_tree(dattr, &top_cpuset); 667 } 668 cpumask_and(doms[0], top_cpuset.effective_cpus, 669 non_isolated_cpus); 670 671 goto done; 672 } 673 674 csa = kmalloc(nr_cpusets() * sizeof(cp), GFP_KERNEL); 675 if (!csa) 676 goto done; 677 csn = 0; 678 679 rcu_read_lock(); 680 cpuset_for_each_descendant_pre(cp, pos_css, &top_cpuset) { 681 if (cp == &top_cpuset) 682 continue; 683 /* 684 * Continue traversing beyond @cp iff @cp has some CPUs and 685 * isn't load balancing. The former is obvious. The 686 * latter: All child cpusets contain a subset of the 687 * parent's cpus, so just skip them, and then we call 688 * update_domain_attr_tree() to calc relax_domain_level of 689 * the corresponding sched domain. 690 */ 691 if (!cpumask_empty(cp->cpus_allowed) && 692 !(is_sched_load_balance(cp) && 693 cpumask_intersects(cp->cpus_allowed, non_isolated_cpus))) 694 continue; 695 696 if (is_sched_load_balance(cp)) 697 csa[csn++] = cp; 698 699 /* skip @cp's subtree */ 700 pos_css = css_rightmost_descendant(pos_css); 701 } 702 rcu_read_unlock(); 703 704 for (i = 0; i < csn; i++) 705 csa[i]->pn = i; 706 ndoms = csn; 707 708 restart: 709 /* Find the best partition (set of sched domains) */ 710 for (i = 0; i < csn; i++) { 711 struct cpuset *a = csa[i]; 712 int apn = a->pn; 713 714 for (j = 0; j < csn; j++) { 715 struct cpuset *b = csa[j]; 716 int bpn = b->pn; 717 718 if (apn != bpn && cpusets_overlap(a, b)) { 719 for (k = 0; k < csn; k++) { 720 struct cpuset *c = csa[k]; 721 722 if (c->pn == bpn) 723 c->pn = apn; 724 } 725 ndoms--; /* one less element */ 726 goto restart; 727 } 728 } 729 } 730 731 /* 732 * Now we know how many domains to create. 733 * Convert <csn, csa> to <ndoms, doms> and populate cpu masks. 734 */ 735 doms = alloc_sched_domains(ndoms); 736 if (!doms) 737 goto done; 738 739 /* 740 * The rest of the code, including the scheduler, can deal with 741 * dattr==NULL case. No need to abort if alloc fails. 742 */ 743 dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL); 744 745 for (nslot = 0, i = 0; i < csn; i++) { 746 struct cpuset *a = csa[i]; 747 struct cpumask *dp; 748 int apn = a->pn; 749 750 if (apn < 0) { 751 /* Skip completed partitions */ 752 continue; 753 } 754 755 dp = doms[nslot]; 756 757 if (nslot == ndoms) { 758 static int warnings = 10; 759 if (warnings) { 760 pr_warn("rebuild_sched_domains confused: nslot %d, ndoms %d, csn %d, i %d, apn %d\n", 761 nslot, ndoms, csn, i, apn); 762 warnings--; 763 } 764 continue; 765 } 766 767 cpumask_clear(dp); 768 if (dattr) 769 *(dattr + nslot) = SD_ATTR_INIT; 770 for (j = i; j < csn; j++) { 771 struct cpuset *b = csa[j]; 772 773 if (apn == b->pn) { 774 cpumask_or(dp, dp, b->effective_cpus); 775 cpumask_and(dp, dp, non_isolated_cpus); 776 if (dattr) 777 update_domain_attr_tree(dattr + nslot, b); 778 779 /* Done with this partition */ 780 b->pn = -1; 781 } 782 } 783 nslot++; 784 } 785 BUG_ON(nslot != ndoms); 786 787 done: 788 free_cpumask_var(non_isolated_cpus); 789 kfree(csa); 790 791 /* 792 * Fallback to the default domain if kmalloc() failed. 793 * See comments in partition_sched_domains(). 794 */ 795 if (doms == NULL) 796 ndoms = 1; 797 798 *domains = doms; 799 *attributes = dattr; 800 return ndoms; 801 } 802 803 /* 804 * Rebuild scheduler domains. 805 * 806 * If the flag 'sched_load_balance' of any cpuset with non-empty 807 * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset 808 * which has that flag enabled, or if any cpuset with a non-empty 809 * 'cpus' is removed, then call this routine to rebuild the 810 * scheduler's dynamic sched domains. 811 * 812 * Call with cpuset_mutex held. Takes get_online_cpus(). 813 */ 814 static void rebuild_sched_domains_locked(void) 815 { 816 struct sched_domain_attr *attr; 817 cpumask_var_t *doms; 818 int ndoms; 819 820 lockdep_assert_held(&cpuset_mutex); 821 get_online_cpus(); 822 823 /* 824 * We have raced with CPU hotplug. Don't do anything to avoid 825 * passing doms with offlined cpu to partition_sched_domains(). 826 * Anyways, hotplug work item will rebuild sched domains. 827 */ 828 if (!cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask)) 829 goto out; 830 831 /* Generate domain masks and attrs */ 832 ndoms = generate_sched_domains(&doms, &attr); 833 834 /* Have scheduler rebuild the domains */ 835 partition_sched_domains(ndoms, doms, attr); 836 out: 837 put_online_cpus(); 838 } 839 #else /* !CONFIG_SMP */ 840 static void rebuild_sched_domains_locked(void) 841 { 842 } 843 #endif /* CONFIG_SMP */ 844 845 void rebuild_sched_domains(void) 846 { 847 mutex_lock(&cpuset_mutex); 848 rebuild_sched_domains_locked(); 849 mutex_unlock(&cpuset_mutex); 850 } 851 852 /** 853 * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset. 854 * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed 855 * 856 * Iterate through each task of @cs updating its cpus_allowed to the 857 * effective cpuset's. As this function is called with cpuset_mutex held, 858 * cpuset membership stays stable. 859 */ 860 static void update_tasks_cpumask(struct cpuset *cs) 861 { 862 struct css_task_iter it; 863 struct task_struct *task; 864 865 css_task_iter_start(&cs->css, &it); 866 while ((task = css_task_iter_next(&it))) 867 set_cpus_allowed_ptr(task, cs->effective_cpus); 868 css_task_iter_end(&it); 869 } 870 871 /* 872 * update_cpumasks_hier - Update effective cpumasks and tasks in the subtree 873 * @cs: the cpuset to consider 874 * @new_cpus: temp variable for calculating new effective_cpus 875 * 876 * When congifured cpumask is changed, the effective cpumasks of this cpuset 877 * and all its descendants need to be updated. 878 * 879 * On legacy hierachy, effective_cpus will be the same with cpu_allowed. 880 * 881 * Called with cpuset_mutex held 882 */ 883 static void update_cpumasks_hier(struct cpuset *cs, struct cpumask *new_cpus) 884 { 885 struct cpuset *cp; 886 struct cgroup_subsys_state *pos_css; 887 bool need_rebuild_sched_domains = false; 888 889 rcu_read_lock(); 890 cpuset_for_each_descendant_pre(cp, pos_css, cs) { 891 struct cpuset *parent = parent_cs(cp); 892 893 cpumask_and(new_cpus, cp->cpus_allowed, parent->effective_cpus); 894 895 /* 896 * If it becomes empty, inherit the effective mask of the 897 * parent, which is guaranteed to have some CPUs. 898 */ 899 if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) && 900 cpumask_empty(new_cpus)) 901 cpumask_copy(new_cpus, parent->effective_cpus); 902 903 /* Skip the whole subtree if the cpumask remains the same. */ 904 if (cpumask_equal(new_cpus, cp->effective_cpus)) { 905 pos_css = css_rightmost_descendant(pos_css); 906 continue; 907 } 908 909 if (!css_tryget_online(&cp->css)) 910 continue; 911 rcu_read_unlock(); 912 913 spin_lock_irq(&callback_lock); 914 cpumask_copy(cp->effective_cpus, new_cpus); 915 spin_unlock_irq(&callback_lock); 916 917 WARN_ON(!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) && 918 !cpumask_equal(cp->cpus_allowed, cp->effective_cpus)); 919 920 update_tasks_cpumask(cp); 921 922 /* 923 * If the effective cpumask of any non-empty cpuset is changed, 924 * we need to rebuild sched domains. 925 */ 926 if (!cpumask_empty(cp->cpus_allowed) && 927 is_sched_load_balance(cp)) 928 need_rebuild_sched_domains = true; 929 930 rcu_read_lock(); 931 css_put(&cp->css); 932 } 933 rcu_read_unlock(); 934 935 if (need_rebuild_sched_domains) 936 rebuild_sched_domains_locked(); 937 } 938 939 /** 940 * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it 941 * @cs: the cpuset to consider 942 * @trialcs: trial cpuset 943 * @buf: buffer of cpu numbers written to this cpuset 944 */ 945 static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, 946 const char *buf) 947 { 948 int retval; 949 950 /* top_cpuset.cpus_allowed tracks cpu_online_mask; it's read-only */ 951 if (cs == &top_cpuset) 952 return -EACCES; 953 954 /* 955 * An empty cpus_allowed is ok only if the cpuset has no tasks. 956 * Since cpulist_parse() fails on an empty mask, we special case 957 * that parsing. The validate_change() call ensures that cpusets 958 * with tasks have cpus. 959 */ 960 if (!*buf) { 961 cpumask_clear(trialcs->cpus_allowed); 962 } else { 963 retval = cpulist_parse(buf, trialcs->cpus_allowed); 964 if (retval < 0) 965 return retval; 966 967 if (!cpumask_subset(trialcs->cpus_allowed, 968 top_cpuset.cpus_allowed)) 969 return -EINVAL; 970 } 971 972 /* Nothing to do if the cpus didn't change */ 973 if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed)) 974 return 0; 975 976 retval = validate_change(cs, trialcs); 977 if (retval < 0) 978 return retval; 979 980 spin_lock_irq(&callback_lock); 981 cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed); 982 spin_unlock_irq(&callback_lock); 983 984 /* use trialcs->cpus_allowed as a temp variable */ 985 update_cpumasks_hier(cs, trialcs->cpus_allowed); 986 return 0; 987 } 988 989 /* 990 * Migrate memory region from one set of nodes to another. This is 991 * performed asynchronously as it can be called from process migration path 992 * holding locks involved in process management. All mm migrations are 993 * performed in the queued order and can be waited for by flushing 994 * cpuset_migrate_mm_wq. 995 */ 996 997 struct cpuset_migrate_mm_work { 998 struct work_struct work; 999 struct mm_struct *mm; 1000 nodemask_t from; 1001 nodemask_t to; 1002 }; 1003 1004 static void cpuset_migrate_mm_workfn(struct work_struct *work) 1005 { 1006 struct cpuset_migrate_mm_work *mwork = 1007 container_of(work, struct cpuset_migrate_mm_work, work); 1008 1009 /* on a wq worker, no need to worry about %current's mems_allowed */ 1010 do_migrate_pages(mwork->mm, &mwork->from, &mwork->to, MPOL_MF_MOVE_ALL); 1011 mmput(mwork->mm); 1012 kfree(mwork); 1013 } 1014 1015 static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from, 1016 const nodemask_t *to) 1017 { 1018 struct cpuset_migrate_mm_work *mwork; 1019 1020 mwork = kzalloc(sizeof(*mwork), GFP_KERNEL); 1021 if (mwork) { 1022 mwork->mm = mm; 1023 mwork->from = *from; 1024 mwork->to = *to; 1025 INIT_WORK(&mwork->work, cpuset_migrate_mm_workfn); 1026 queue_work(cpuset_migrate_mm_wq, &mwork->work); 1027 } else { 1028 mmput(mm); 1029 } 1030 } 1031 1032 static void cpuset_post_attach(void) 1033 { 1034 flush_workqueue(cpuset_migrate_mm_wq); 1035 } 1036 1037 /* 1038 * cpuset_change_task_nodemask - change task's mems_allowed and mempolicy 1039 * @tsk: the task to change 1040 * @newmems: new nodes that the task will be set 1041 * 1042 * We use the mems_allowed_seq seqlock to safely update both tsk->mems_allowed 1043 * and rebind an eventual tasks' mempolicy. If the task is allocating in 1044 * parallel, it might temporarily see an empty intersection, which results in 1045 * a seqlock check and retry before OOM or allocation failure. 1046 */ 1047 static void cpuset_change_task_nodemask(struct task_struct *tsk, 1048 nodemask_t *newmems) 1049 { 1050 task_lock(tsk); 1051 1052 local_irq_disable(); 1053 write_seqcount_begin(&tsk->mems_allowed_seq); 1054 1055 nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems); 1056 mpol_rebind_task(tsk, newmems); 1057 tsk->mems_allowed = *newmems; 1058 1059 write_seqcount_end(&tsk->mems_allowed_seq); 1060 local_irq_enable(); 1061 1062 task_unlock(tsk); 1063 } 1064 1065 static void *cpuset_being_rebound; 1066 1067 /** 1068 * update_tasks_nodemask - Update the nodemasks of tasks in the cpuset. 1069 * @cs: the cpuset in which each task's mems_allowed mask needs to be changed 1070 * 1071 * Iterate through each task of @cs updating its mems_allowed to the 1072 * effective cpuset's. As this function is called with cpuset_mutex held, 1073 * cpuset membership stays stable. 1074 */ 1075 static void update_tasks_nodemask(struct cpuset *cs) 1076 { 1077 static nodemask_t newmems; /* protected by cpuset_mutex */ 1078 struct css_task_iter it; 1079 struct task_struct *task; 1080 1081 cpuset_being_rebound = cs; /* causes mpol_dup() rebind */ 1082 1083 guarantee_online_mems(cs, &newmems); 1084 1085 /* 1086 * The mpol_rebind_mm() call takes mmap_sem, which we couldn't 1087 * take while holding tasklist_lock. Forks can happen - the 1088 * mpol_dup() cpuset_being_rebound check will catch such forks, 1089 * and rebind their vma mempolicies too. Because we still hold 1090 * the global cpuset_mutex, we know that no other rebind effort 1091 * will be contending for the global variable cpuset_being_rebound. 1092 * It's ok if we rebind the same mm twice; mpol_rebind_mm() 1093 * is idempotent. Also migrate pages in each mm to new nodes. 1094 */ 1095 css_task_iter_start(&cs->css, &it); 1096 while ((task = css_task_iter_next(&it))) { 1097 struct mm_struct *mm; 1098 bool migrate; 1099 1100 cpuset_change_task_nodemask(task, &newmems); 1101 1102 mm = get_task_mm(task); 1103 if (!mm) 1104 continue; 1105 1106 migrate = is_memory_migrate(cs); 1107 1108 mpol_rebind_mm(mm, &cs->mems_allowed); 1109 if (migrate) 1110 cpuset_migrate_mm(mm, &cs->old_mems_allowed, &newmems); 1111 else 1112 mmput(mm); 1113 } 1114 css_task_iter_end(&it); 1115 1116 /* 1117 * All the tasks' nodemasks have been updated, update 1118 * cs->old_mems_allowed. 1119 */ 1120 cs->old_mems_allowed = newmems; 1121 1122 /* We're done rebinding vmas to this cpuset's new mems_allowed. */ 1123 cpuset_being_rebound = NULL; 1124 } 1125 1126 /* 1127 * update_nodemasks_hier - Update effective nodemasks and tasks in the subtree 1128 * @cs: the cpuset to consider 1129 * @new_mems: a temp variable for calculating new effective_mems 1130 * 1131 * When configured nodemask is changed, the effective nodemasks of this cpuset 1132 * and all its descendants need to be updated. 1133 * 1134 * On legacy hiearchy, effective_mems will be the same with mems_allowed. 1135 * 1136 * Called with cpuset_mutex held 1137 */ 1138 static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems) 1139 { 1140 struct cpuset *cp; 1141 struct cgroup_subsys_state *pos_css; 1142 1143 rcu_read_lock(); 1144 cpuset_for_each_descendant_pre(cp, pos_css, cs) { 1145 struct cpuset *parent = parent_cs(cp); 1146 1147 nodes_and(*new_mems, cp->mems_allowed, parent->effective_mems); 1148 1149 /* 1150 * If it becomes empty, inherit the effective mask of the 1151 * parent, which is guaranteed to have some MEMs. 1152 */ 1153 if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) && 1154 nodes_empty(*new_mems)) 1155 *new_mems = parent->effective_mems; 1156 1157 /* Skip the whole subtree if the nodemask remains the same. */ 1158 if (nodes_equal(*new_mems, cp->effective_mems)) { 1159 pos_css = css_rightmost_descendant(pos_css); 1160 continue; 1161 } 1162 1163 if (!css_tryget_online(&cp->css)) 1164 continue; 1165 rcu_read_unlock(); 1166 1167 spin_lock_irq(&callback_lock); 1168 cp->effective_mems = *new_mems; 1169 spin_unlock_irq(&callback_lock); 1170 1171 WARN_ON(!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) && 1172 !nodes_equal(cp->mems_allowed, cp->effective_mems)); 1173 1174 update_tasks_nodemask(cp); 1175 1176 rcu_read_lock(); 1177 css_put(&cp->css); 1178 } 1179 rcu_read_unlock(); 1180 } 1181 1182 /* 1183 * Handle user request to change the 'mems' memory placement 1184 * of a cpuset. Needs to validate the request, update the 1185 * cpusets mems_allowed, and for each task in the cpuset, 1186 * update mems_allowed and rebind task's mempolicy and any vma 1187 * mempolicies and if the cpuset is marked 'memory_migrate', 1188 * migrate the tasks pages to the new memory. 1189 * 1190 * Call with cpuset_mutex held. May take callback_lock during call. 1191 * Will take tasklist_lock, scan tasklist for tasks in cpuset cs, 1192 * lock each such tasks mm->mmap_sem, scan its vma's and rebind 1193 * their mempolicies to the cpusets new mems_allowed. 1194 */ 1195 static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs, 1196 const char *buf) 1197 { 1198 int retval; 1199 1200 /* 1201 * top_cpuset.mems_allowed tracks node_stats[N_MEMORY]; 1202 * it's read-only 1203 */ 1204 if (cs == &top_cpuset) { 1205 retval = -EACCES; 1206 goto done; 1207 } 1208 1209 /* 1210 * An empty mems_allowed is ok iff there are no tasks in the cpuset. 1211 * Since nodelist_parse() fails on an empty mask, we special case 1212 * that parsing. The validate_change() call ensures that cpusets 1213 * with tasks have memory. 1214 */ 1215 if (!*buf) { 1216 nodes_clear(trialcs->mems_allowed); 1217 } else { 1218 retval = nodelist_parse(buf, trialcs->mems_allowed); 1219 if (retval < 0) 1220 goto done; 1221 1222 if (!nodes_subset(trialcs->mems_allowed, 1223 top_cpuset.mems_allowed)) { 1224 retval = -EINVAL; 1225 goto done; 1226 } 1227 } 1228 1229 if (nodes_equal(cs->mems_allowed, trialcs->mems_allowed)) { 1230 retval = 0; /* Too easy - nothing to do */ 1231 goto done; 1232 } 1233 retval = validate_change(cs, trialcs); 1234 if (retval < 0) 1235 goto done; 1236 1237 spin_lock_irq(&callback_lock); 1238 cs->mems_allowed = trialcs->mems_allowed; 1239 spin_unlock_irq(&callback_lock); 1240 1241 /* use trialcs->mems_allowed as a temp variable */ 1242 update_nodemasks_hier(cs, &trialcs->mems_allowed); 1243 done: 1244 return retval; 1245 } 1246 1247 int current_cpuset_is_being_rebound(void) 1248 { 1249 int ret; 1250 1251 rcu_read_lock(); 1252 ret = task_cs(current) == cpuset_being_rebound; 1253 rcu_read_unlock(); 1254 1255 return ret; 1256 } 1257 1258 static int update_relax_domain_level(struct cpuset *cs, s64 val) 1259 { 1260 #ifdef CONFIG_SMP 1261 if (val < -1 || val >= sched_domain_level_max) 1262 return -EINVAL; 1263 #endif 1264 1265 if (val != cs->relax_domain_level) { 1266 cs->relax_domain_level = val; 1267 if (!cpumask_empty(cs->cpus_allowed) && 1268 is_sched_load_balance(cs)) 1269 rebuild_sched_domains_locked(); 1270 } 1271 1272 return 0; 1273 } 1274 1275 /** 1276 * update_tasks_flags - update the spread flags of tasks in the cpuset. 1277 * @cs: the cpuset in which each task's spread flags needs to be changed 1278 * 1279 * Iterate through each task of @cs updating its spread flags. As this 1280 * function is called with cpuset_mutex held, cpuset membership stays 1281 * stable. 1282 */ 1283 static void update_tasks_flags(struct cpuset *cs) 1284 { 1285 struct css_task_iter it; 1286 struct task_struct *task; 1287 1288 css_task_iter_start(&cs->css, &it); 1289 while ((task = css_task_iter_next(&it))) 1290 cpuset_update_task_spread_flag(cs, task); 1291 css_task_iter_end(&it); 1292 } 1293 1294 /* 1295 * update_flag - read a 0 or a 1 in a file and update associated flag 1296 * bit: the bit to update (see cpuset_flagbits_t) 1297 * cs: the cpuset to update 1298 * turning_on: whether the flag is being set or cleared 1299 * 1300 * Call with cpuset_mutex held. 1301 */ 1302 1303 static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, 1304 int turning_on) 1305 { 1306 struct cpuset *trialcs; 1307 int balance_flag_changed; 1308 int spread_flag_changed; 1309 int err; 1310 1311 trialcs = alloc_trial_cpuset(cs); 1312 if (!trialcs) 1313 return -ENOMEM; 1314 1315 if (turning_on) 1316 set_bit(bit, &trialcs->flags); 1317 else 1318 clear_bit(bit, &trialcs->flags); 1319 1320 err = validate_change(cs, trialcs); 1321 if (err < 0) 1322 goto out; 1323 1324 balance_flag_changed = (is_sched_load_balance(cs) != 1325 is_sched_load_balance(trialcs)); 1326 1327 spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs)) 1328 || (is_spread_page(cs) != is_spread_page(trialcs))); 1329 1330 spin_lock_irq(&callback_lock); 1331 cs->flags = trialcs->flags; 1332 spin_unlock_irq(&callback_lock); 1333 1334 if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed) 1335 rebuild_sched_domains_locked(); 1336 1337 if (spread_flag_changed) 1338 update_tasks_flags(cs); 1339 out: 1340 free_trial_cpuset(trialcs); 1341 return err; 1342 } 1343 1344 /* 1345 * Frequency meter - How fast is some event occurring? 1346 * 1347 * These routines manage a digitally filtered, constant time based, 1348 * event frequency meter. There are four routines: 1349 * fmeter_init() - initialize a frequency meter. 1350 * fmeter_markevent() - called each time the event happens. 1351 * fmeter_getrate() - returns the recent rate of such events. 1352 * fmeter_update() - internal routine used to update fmeter. 1353 * 1354 * A common data structure is passed to each of these routines, 1355 * which is used to keep track of the state required to manage the 1356 * frequency meter and its digital filter. 1357 * 1358 * The filter works on the number of events marked per unit time. 1359 * The filter is single-pole low-pass recursive (IIR). The time unit 1360 * is 1 second. Arithmetic is done using 32-bit integers scaled to 1361 * simulate 3 decimal digits of precision (multiplied by 1000). 1362 * 1363 * With an FM_COEF of 933, and a time base of 1 second, the filter 1364 * has a half-life of 10 seconds, meaning that if the events quit 1365 * happening, then the rate returned from the fmeter_getrate() 1366 * will be cut in half each 10 seconds, until it converges to zero. 1367 * 1368 * It is not worth doing a real infinitely recursive filter. If more 1369 * than FM_MAXTICKS ticks have elapsed since the last filter event, 1370 * just compute FM_MAXTICKS ticks worth, by which point the level 1371 * will be stable. 1372 * 1373 * Limit the count of unprocessed events to FM_MAXCNT, so as to avoid 1374 * arithmetic overflow in the fmeter_update() routine. 1375 * 1376 * Given the simple 32 bit integer arithmetic used, this meter works 1377 * best for reporting rates between one per millisecond (msec) and 1378 * one per 32 (approx) seconds. At constant rates faster than one 1379 * per msec it maxes out at values just under 1,000,000. At constant 1380 * rates between one per msec, and one per second it will stabilize 1381 * to a value N*1000, where N is the rate of events per second. 1382 * At constant rates between one per second and one per 32 seconds, 1383 * it will be choppy, moving up on the seconds that have an event, 1384 * and then decaying until the next event. At rates slower than 1385 * about one in 32 seconds, it decays all the way back to zero between 1386 * each event. 1387 */ 1388 1389 #define FM_COEF 933 /* coefficient for half-life of 10 secs */ 1390 #define FM_MAXTICKS ((u32)99) /* useless computing more ticks than this */ 1391 #define FM_MAXCNT 1000000 /* limit cnt to avoid overflow */ 1392 #define FM_SCALE 1000 /* faux fixed point scale */ 1393 1394 /* Initialize a frequency meter */ 1395 static void fmeter_init(struct fmeter *fmp) 1396 { 1397 fmp->cnt = 0; 1398 fmp->val = 0; 1399 fmp->time = 0; 1400 spin_lock_init(&fmp->lock); 1401 } 1402 1403 /* Internal meter update - process cnt events and update value */ 1404 static void fmeter_update(struct fmeter *fmp) 1405 { 1406 time64_t now; 1407 u32 ticks; 1408 1409 now = ktime_get_seconds(); 1410 ticks = now - fmp->time; 1411 1412 if (ticks == 0) 1413 return; 1414 1415 ticks = min(FM_MAXTICKS, ticks); 1416 while (ticks-- > 0) 1417 fmp->val = (FM_COEF * fmp->val) / FM_SCALE; 1418 fmp->time = now; 1419 1420 fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE; 1421 fmp->cnt = 0; 1422 } 1423 1424 /* Process any previous ticks, then bump cnt by one (times scale). */ 1425 static void fmeter_markevent(struct fmeter *fmp) 1426 { 1427 spin_lock(&fmp->lock); 1428 fmeter_update(fmp); 1429 fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE); 1430 spin_unlock(&fmp->lock); 1431 } 1432 1433 /* Process any previous ticks, then return current value. */ 1434 static int fmeter_getrate(struct fmeter *fmp) 1435 { 1436 int val; 1437 1438 spin_lock(&fmp->lock); 1439 fmeter_update(fmp); 1440 val = fmp->val; 1441 spin_unlock(&fmp->lock); 1442 return val; 1443 } 1444 1445 static struct cpuset *cpuset_attach_old_cs; 1446 1447 /* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */ 1448 static int cpuset_can_attach(struct cgroup_taskset *tset) 1449 { 1450 struct cgroup_subsys_state *css; 1451 struct cpuset *cs; 1452 struct task_struct *task; 1453 int ret; 1454 1455 /* used later by cpuset_attach() */ 1456 cpuset_attach_old_cs = task_cs(cgroup_taskset_first(tset, &css)); 1457 cs = css_cs(css); 1458 1459 mutex_lock(&cpuset_mutex); 1460 1461 /* allow moving tasks into an empty cpuset if on default hierarchy */ 1462 ret = -ENOSPC; 1463 if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) && 1464 (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))) 1465 goto out_unlock; 1466 1467 cgroup_taskset_for_each(task, css, tset) { 1468 ret = task_can_attach(task, cs->cpus_allowed); 1469 if (ret) 1470 goto out_unlock; 1471 ret = security_task_setscheduler(task); 1472 if (ret) 1473 goto out_unlock; 1474 } 1475 1476 /* 1477 * Mark attach is in progress. This makes validate_change() fail 1478 * changes which zero cpus/mems_allowed. 1479 */ 1480 cs->attach_in_progress++; 1481 ret = 0; 1482 out_unlock: 1483 mutex_unlock(&cpuset_mutex); 1484 return ret; 1485 } 1486 1487 static void cpuset_cancel_attach(struct cgroup_taskset *tset) 1488 { 1489 struct cgroup_subsys_state *css; 1490 struct cpuset *cs; 1491 1492 cgroup_taskset_first(tset, &css); 1493 cs = css_cs(css); 1494 1495 mutex_lock(&cpuset_mutex); 1496 css_cs(css)->attach_in_progress--; 1497 mutex_unlock(&cpuset_mutex); 1498 } 1499 1500 /* 1501 * Protected by cpuset_mutex. cpus_attach is used only by cpuset_attach() 1502 * but we can't allocate it dynamically there. Define it global and 1503 * allocate from cpuset_init(). 1504 */ 1505 static cpumask_var_t cpus_attach; 1506 1507 static void cpuset_attach(struct cgroup_taskset *tset) 1508 { 1509 /* static buf protected by cpuset_mutex */ 1510 static nodemask_t cpuset_attach_nodemask_to; 1511 struct task_struct *task; 1512 struct task_struct *leader; 1513 struct cgroup_subsys_state *css; 1514 struct cpuset *cs; 1515 struct cpuset *oldcs = cpuset_attach_old_cs; 1516 1517 cgroup_taskset_first(tset, &css); 1518 cs = css_cs(css); 1519 1520 mutex_lock(&cpuset_mutex); 1521 1522 /* prepare for attach */ 1523 if (cs == &top_cpuset) 1524 cpumask_copy(cpus_attach, cpu_possible_mask); 1525 else 1526 guarantee_online_cpus(cs, cpus_attach); 1527 1528 guarantee_online_mems(cs, &cpuset_attach_nodemask_to); 1529 1530 cgroup_taskset_for_each(task, css, tset) { 1531 /* 1532 * can_attach beforehand should guarantee that this doesn't 1533 * fail. TODO: have a better way to handle failure here 1534 */ 1535 WARN_ON_ONCE(set_cpus_allowed_ptr(task, cpus_attach)); 1536 1537 cpuset_change_task_nodemask(task, &cpuset_attach_nodemask_to); 1538 cpuset_update_task_spread_flag(cs, task); 1539 } 1540 1541 /* 1542 * Change mm for all threadgroup leaders. This is expensive and may 1543 * sleep and should be moved outside migration path proper. 1544 */ 1545 cpuset_attach_nodemask_to = cs->effective_mems; 1546 cgroup_taskset_for_each_leader(leader, css, tset) { 1547 struct mm_struct *mm = get_task_mm(leader); 1548 1549 if (mm) { 1550 mpol_rebind_mm(mm, &cpuset_attach_nodemask_to); 1551 1552 /* 1553 * old_mems_allowed is the same with mems_allowed 1554 * here, except if this task is being moved 1555 * automatically due to hotplug. In that case 1556 * @mems_allowed has been updated and is empty, so 1557 * @old_mems_allowed is the right nodesets that we 1558 * migrate mm from. 1559 */ 1560 if (is_memory_migrate(cs)) 1561 cpuset_migrate_mm(mm, &oldcs->old_mems_allowed, 1562 &cpuset_attach_nodemask_to); 1563 else 1564 mmput(mm); 1565 } 1566 } 1567 1568 cs->old_mems_allowed = cpuset_attach_nodemask_to; 1569 1570 cs->attach_in_progress--; 1571 if (!cs->attach_in_progress) 1572 wake_up(&cpuset_attach_wq); 1573 1574 mutex_unlock(&cpuset_mutex); 1575 } 1576 1577 /* The various types of files and directories in a cpuset file system */ 1578 1579 typedef enum { 1580 FILE_MEMORY_MIGRATE, 1581 FILE_CPULIST, 1582 FILE_MEMLIST, 1583 FILE_EFFECTIVE_CPULIST, 1584 FILE_EFFECTIVE_MEMLIST, 1585 FILE_CPU_EXCLUSIVE, 1586 FILE_MEM_EXCLUSIVE, 1587 FILE_MEM_HARDWALL, 1588 FILE_SCHED_LOAD_BALANCE, 1589 FILE_SCHED_RELAX_DOMAIN_LEVEL, 1590 FILE_MEMORY_PRESSURE_ENABLED, 1591 FILE_MEMORY_PRESSURE, 1592 FILE_SPREAD_PAGE, 1593 FILE_SPREAD_SLAB, 1594 } cpuset_filetype_t; 1595 1596 static int cpuset_write_u64(struct cgroup_subsys_state *css, struct cftype *cft, 1597 u64 val) 1598 { 1599 struct cpuset *cs = css_cs(css); 1600 cpuset_filetype_t type = cft->private; 1601 int retval = 0; 1602 1603 mutex_lock(&cpuset_mutex); 1604 if (!is_cpuset_online(cs)) { 1605 retval = -ENODEV; 1606 goto out_unlock; 1607 } 1608 1609 switch (type) { 1610 case FILE_CPU_EXCLUSIVE: 1611 retval = update_flag(CS_CPU_EXCLUSIVE, cs, val); 1612 break; 1613 case FILE_MEM_EXCLUSIVE: 1614 retval = update_flag(CS_MEM_EXCLUSIVE, cs, val); 1615 break; 1616 case FILE_MEM_HARDWALL: 1617 retval = update_flag(CS_MEM_HARDWALL, cs, val); 1618 break; 1619 case FILE_SCHED_LOAD_BALANCE: 1620 retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val); 1621 break; 1622 case FILE_MEMORY_MIGRATE: 1623 retval = update_flag(CS_MEMORY_MIGRATE, cs, val); 1624 break; 1625 case FILE_MEMORY_PRESSURE_ENABLED: 1626 cpuset_memory_pressure_enabled = !!val; 1627 break; 1628 case FILE_SPREAD_PAGE: 1629 retval = update_flag(CS_SPREAD_PAGE, cs, val); 1630 break; 1631 case FILE_SPREAD_SLAB: 1632 retval = update_flag(CS_SPREAD_SLAB, cs, val); 1633 break; 1634 default: 1635 retval = -EINVAL; 1636 break; 1637 } 1638 out_unlock: 1639 mutex_unlock(&cpuset_mutex); 1640 return retval; 1641 } 1642 1643 static int cpuset_write_s64(struct cgroup_subsys_state *css, struct cftype *cft, 1644 s64 val) 1645 { 1646 struct cpuset *cs = css_cs(css); 1647 cpuset_filetype_t type = cft->private; 1648 int retval = -ENODEV; 1649 1650 mutex_lock(&cpuset_mutex); 1651 if (!is_cpuset_online(cs)) 1652 goto out_unlock; 1653 1654 switch (type) { 1655 case FILE_SCHED_RELAX_DOMAIN_LEVEL: 1656 retval = update_relax_domain_level(cs, val); 1657 break; 1658 default: 1659 retval = -EINVAL; 1660 break; 1661 } 1662 out_unlock: 1663 mutex_unlock(&cpuset_mutex); 1664 return retval; 1665 } 1666 1667 /* 1668 * Common handling for a write to a "cpus" or "mems" file. 1669 */ 1670 static ssize_t cpuset_write_resmask(struct kernfs_open_file *of, 1671 char *buf, size_t nbytes, loff_t off) 1672 { 1673 struct cpuset *cs = css_cs(of_css(of)); 1674 struct cpuset *trialcs; 1675 int retval = -ENODEV; 1676 1677 buf = strstrip(buf); 1678 1679 /* 1680 * CPU or memory hotunplug may leave @cs w/o any execution 1681 * resources, in which case the hotplug code asynchronously updates 1682 * configuration and transfers all tasks to the nearest ancestor 1683 * which can execute. 1684 * 1685 * As writes to "cpus" or "mems" may restore @cs's execution 1686 * resources, wait for the previously scheduled operations before 1687 * proceeding, so that we don't end up keep removing tasks added 1688 * after execution capability is restored. 1689 * 1690 * cpuset_hotplug_work calls back into cgroup core via 1691 * cgroup_transfer_tasks() and waiting for it from a cgroupfs 1692 * operation like this one can lead to a deadlock through kernfs 1693 * active_ref protection. Let's break the protection. Losing the 1694 * protection is okay as we check whether @cs is online after 1695 * grabbing cpuset_mutex anyway. This only happens on the legacy 1696 * hierarchies. 1697 */ 1698 css_get(&cs->css); 1699 kernfs_break_active_protection(of->kn); 1700 flush_work(&cpuset_hotplug_work); 1701 1702 mutex_lock(&cpuset_mutex); 1703 if (!is_cpuset_online(cs)) 1704 goto out_unlock; 1705 1706 trialcs = alloc_trial_cpuset(cs); 1707 if (!trialcs) { 1708 retval = -ENOMEM; 1709 goto out_unlock; 1710 } 1711 1712 switch (of_cft(of)->private) { 1713 case FILE_CPULIST: 1714 retval = update_cpumask(cs, trialcs, buf); 1715 break; 1716 case FILE_MEMLIST: 1717 retval = update_nodemask(cs, trialcs, buf); 1718 break; 1719 default: 1720 retval = -EINVAL; 1721 break; 1722 } 1723 1724 free_trial_cpuset(trialcs); 1725 out_unlock: 1726 mutex_unlock(&cpuset_mutex); 1727 kernfs_unbreak_active_protection(of->kn); 1728 css_put(&cs->css); 1729 flush_workqueue(cpuset_migrate_mm_wq); 1730 return retval ?: nbytes; 1731 } 1732 1733 /* 1734 * These ascii lists should be read in a single call, by using a user 1735 * buffer large enough to hold the entire map. If read in smaller 1736 * chunks, there is no guarantee of atomicity. Since the display format 1737 * used, list of ranges of sequential numbers, is variable length, 1738 * and since these maps can change value dynamically, one could read 1739 * gibberish by doing partial reads while a list was changing. 1740 */ 1741 static int cpuset_common_seq_show(struct seq_file *sf, void *v) 1742 { 1743 struct cpuset *cs = css_cs(seq_css(sf)); 1744 cpuset_filetype_t type = seq_cft(sf)->private; 1745 int ret = 0; 1746 1747 spin_lock_irq(&callback_lock); 1748 1749 switch (type) { 1750 case FILE_CPULIST: 1751 seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->cpus_allowed)); 1752 break; 1753 case FILE_MEMLIST: 1754 seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->mems_allowed)); 1755 break; 1756 case FILE_EFFECTIVE_CPULIST: 1757 seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->effective_cpus)); 1758 break; 1759 case FILE_EFFECTIVE_MEMLIST: 1760 seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->effective_mems)); 1761 break; 1762 default: 1763 ret = -EINVAL; 1764 } 1765 1766 spin_unlock_irq(&callback_lock); 1767 return ret; 1768 } 1769 1770 static u64 cpuset_read_u64(struct cgroup_subsys_state *css, struct cftype *cft) 1771 { 1772 struct cpuset *cs = css_cs(css); 1773 cpuset_filetype_t type = cft->private; 1774 switch (type) { 1775 case FILE_CPU_EXCLUSIVE: 1776 return is_cpu_exclusive(cs); 1777 case FILE_MEM_EXCLUSIVE: 1778 return is_mem_exclusive(cs); 1779 case FILE_MEM_HARDWALL: 1780 return is_mem_hardwall(cs); 1781 case FILE_SCHED_LOAD_BALANCE: 1782 return is_sched_load_balance(cs); 1783 case FILE_MEMORY_MIGRATE: 1784 return is_memory_migrate(cs); 1785 case FILE_MEMORY_PRESSURE_ENABLED: 1786 return cpuset_memory_pressure_enabled; 1787 case FILE_MEMORY_PRESSURE: 1788 return fmeter_getrate(&cs->fmeter); 1789 case FILE_SPREAD_PAGE: 1790 return is_spread_page(cs); 1791 case FILE_SPREAD_SLAB: 1792 return is_spread_slab(cs); 1793 default: 1794 BUG(); 1795 } 1796 1797 /* Unreachable but makes gcc happy */ 1798 return 0; 1799 } 1800 1801 static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft) 1802 { 1803 struct cpuset *cs = css_cs(css); 1804 cpuset_filetype_t type = cft->private; 1805 switch (type) { 1806 case FILE_SCHED_RELAX_DOMAIN_LEVEL: 1807 return cs->relax_domain_level; 1808 default: 1809 BUG(); 1810 } 1811 1812 /* Unrechable but makes gcc happy */ 1813 return 0; 1814 } 1815 1816 1817 /* 1818 * for the common functions, 'private' gives the type of file 1819 */ 1820 1821 static struct cftype files[] = { 1822 { 1823 .name = "cpus", 1824 .seq_show = cpuset_common_seq_show, 1825 .write = cpuset_write_resmask, 1826 .max_write_len = (100U + 6 * NR_CPUS), 1827 .private = FILE_CPULIST, 1828 }, 1829 1830 { 1831 .name = "mems", 1832 .seq_show = cpuset_common_seq_show, 1833 .write = cpuset_write_resmask, 1834 .max_write_len = (100U + 6 * MAX_NUMNODES), 1835 .private = FILE_MEMLIST, 1836 }, 1837 1838 { 1839 .name = "effective_cpus", 1840 .seq_show = cpuset_common_seq_show, 1841 .private = FILE_EFFECTIVE_CPULIST, 1842 }, 1843 1844 { 1845 .name = "effective_mems", 1846 .seq_show = cpuset_common_seq_show, 1847 .private = FILE_EFFECTIVE_MEMLIST, 1848 }, 1849 1850 { 1851 .name = "cpu_exclusive", 1852 .read_u64 = cpuset_read_u64, 1853 .write_u64 = cpuset_write_u64, 1854 .private = FILE_CPU_EXCLUSIVE, 1855 }, 1856 1857 { 1858 .name = "mem_exclusive", 1859 .read_u64 = cpuset_read_u64, 1860 .write_u64 = cpuset_write_u64, 1861 .private = FILE_MEM_EXCLUSIVE, 1862 }, 1863 1864 { 1865 .name = "mem_hardwall", 1866 .read_u64 = cpuset_read_u64, 1867 .write_u64 = cpuset_write_u64, 1868 .private = FILE_MEM_HARDWALL, 1869 }, 1870 1871 { 1872 .name = "sched_load_balance", 1873 .read_u64 = cpuset_read_u64, 1874 .write_u64 = cpuset_write_u64, 1875 .private = FILE_SCHED_LOAD_BALANCE, 1876 }, 1877 1878 { 1879 .name = "sched_relax_domain_level", 1880 .read_s64 = cpuset_read_s64, 1881 .write_s64 = cpuset_write_s64, 1882 .private = FILE_SCHED_RELAX_DOMAIN_LEVEL, 1883 }, 1884 1885 { 1886 .name = "memory_migrate", 1887 .read_u64 = cpuset_read_u64, 1888 .write_u64 = cpuset_write_u64, 1889 .private = FILE_MEMORY_MIGRATE, 1890 }, 1891 1892 { 1893 .name = "memory_pressure", 1894 .read_u64 = cpuset_read_u64, 1895 }, 1896 1897 { 1898 .name = "memory_spread_page", 1899 .read_u64 = cpuset_read_u64, 1900 .write_u64 = cpuset_write_u64, 1901 .private = FILE_SPREAD_PAGE, 1902 }, 1903 1904 { 1905 .name = "memory_spread_slab", 1906 .read_u64 = cpuset_read_u64, 1907 .write_u64 = cpuset_write_u64, 1908 .private = FILE_SPREAD_SLAB, 1909 }, 1910 1911 { 1912 .name = "memory_pressure_enabled", 1913 .flags = CFTYPE_ONLY_ON_ROOT, 1914 .read_u64 = cpuset_read_u64, 1915 .write_u64 = cpuset_write_u64, 1916 .private = FILE_MEMORY_PRESSURE_ENABLED, 1917 }, 1918 1919 { } /* terminate */ 1920 }; 1921 1922 /* 1923 * cpuset_css_alloc - allocate a cpuset css 1924 * cgrp: control group that the new cpuset will be part of 1925 */ 1926 1927 static struct cgroup_subsys_state * 1928 cpuset_css_alloc(struct cgroup_subsys_state *parent_css) 1929 { 1930 struct cpuset *cs; 1931 1932 if (!parent_css) 1933 return &top_cpuset.css; 1934 1935 cs = kzalloc(sizeof(*cs), GFP_KERNEL); 1936 if (!cs) 1937 return ERR_PTR(-ENOMEM); 1938 if (!alloc_cpumask_var(&cs->cpus_allowed, GFP_KERNEL)) 1939 goto free_cs; 1940 if (!alloc_cpumask_var(&cs->effective_cpus, GFP_KERNEL)) 1941 goto free_cpus; 1942 1943 set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags); 1944 cpumask_clear(cs->cpus_allowed); 1945 nodes_clear(cs->mems_allowed); 1946 cpumask_clear(cs->effective_cpus); 1947 nodes_clear(cs->effective_mems); 1948 fmeter_init(&cs->fmeter); 1949 cs->relax_domain_level = -1; 1950 1951 return &cs->css; 1952 1953 free_cpus: 1954 free_cpumask_var(cs->cpus_allowed); 1955 free_cs: 1956 kfree(cs); 1957 return ERR_PTR(-ENOMEM); 1958 } 1959 1960 static int cpuset_css_online(struct cgroup_subsys_state *css) 1961 { 1962 struct cpuset *cs = css_cs(css); 1963 struct cpuset *parent = parent_cs(cs); 1964 struct cpuset *tmp_cs; 1965 struct cgroup_subsys_state *pos_css; 1966 1967 if (!parent) 1968 return 0; 1969 1970 mutex_lock(&cpuset_mutex); 1971 1972 set_bit(CS_ONLINE, &cs->flags); 1973 if (is_spread_page(parent)) 1974 set_bit(CS_SPREAD_PAGE, &cs->flags); 1975 if (is_spread_slab(parent)) 1976 set_bit(CS_SPREAD_SLAB, &cs->flags); 1977 1978 cpuset_inc(); 1979 1980 spin_lock_irq(&callback_lock); 1981 if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys)) { 1982 cpumask_copy(cs->effective_cpus, parent->effective_cpus); 1983 cs->effective_mems = parent->effective_mems; 1984 } 1985 spin_unlock_irq(&callback_lock); 1986 1987 if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags)) 1988 goto out_unlock; 1989 1990 /* 1991 * Clone @parent's configuration if CGRP_CPUSET_CLONE_CHILDREN is 1992 * set. This flag handling is implemented in cgroup core for 1993 * histrical reasons - the flag may be specified during mount. 1994 * 1995 * Currently, if any sibling cpusets have exclusive cpus or mem, we 1996 * refuse to clone the configuration - thereby refusing the task to 1997 * be entered, and as a result refusing the sys_unshare() or 1998 * clone() which initiated it. If this becomes a problem for some 1999 * users who wish to allow that scenario, then this could be 2000 * changed to grant parent->cpus_allowed-sibling_cpus_exclusive 2001 * (and likewise for mems) to the new cgroup. 2002 */ 2003 rcu_read_lock(); 2004 cpuset_for_each_child(tmp_cs, pos_css, parent) { 2005 if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs)) { 2006 rcu_read_unlock(); 2007 goto out_unlock; 2008 } 2009 } 2010 rcu_read_unlock(); 2011 2012 spin_lock_irq(&callback_lock); 2013 cs->mems_allowed = parent->mems_allowed; 2014 cs->effective_mems = parent->mems_allowed; 2015 cpumask_copy(cs->cpus_allowed, parent->cpus_allowed); 2016 cpumask_copy(cs->effective_cpus, parent->cpus_allowed); 2017 spin_unlock_irq(&callback_lock); 2018 out_unlock: 2019 mutex_unlock(&cpuset_mutex); 2020 return 0; 2021 } 2022 2023 /* 2024 * If the cpuset being removed has its flag 'sched_load_balance' 2025 * enabled, then simulate turning sched_load_balance off, which 2026 * will call rebuild_sched_domains_locked(). 2027 */ 2028 2029 static void cpuset_css_offline(struct cgroup_subsys_state *css) 2030 { 2031 struct cpuset *cs = css_cs(css); 2032 2033 mutex_lock(&cpuset_mutex); 2034 2035 if (is_sched_load_balance(cs)) 2036 update_flag(CS_SCHED_LOAD_BALANCE, cs, 0); 2037 2038 cpuset_dec(); 2039 clear_bit(CS_ONLINE, &cs->flags); 2040 2041 mutex_unlock(&cpuset_mutex); 2042 } 2043 2044 static void cpuset_css_free(struct cgroup_subsys_state *css) 2045 { 2046 struct cpuset *cs = css_cs(css); 2047 2048 free_cpumask_var(cs->effective_cpus); 2049 free_cpumask_var(cs->cpus_allowed); 2050 kfree(cs); 2051 } 2052 2053 static void cpuset_bind(struct cgroup_subsys_state *root_css) 2054 { 2055 mutex_lock(&cpuset_mutex); 2056 spin_lock_irq(&callback_lock); 2057 2058 if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys)) { 2059 cpumask_copy(top_cpuset.cpus_allowed, cpu_possible_mask); 2060 top_cpuset.mems_allowed = node_possible_map; 2061 } else { 2062 cpumask_copy(top_cpuset.cpus_allowed, 2063 top_cpuset.effective_cpus); 2064 top_cpuset.mems_allowed = top_cpuset.effective_mems; 2065 } 2066 2067 spin_unlock_irq(&callback_lock); 2068 mutex_unlock(&cpuset_mutex); 2069 } 2070 2071 /* 2072 * Make sure the new task conform to the current state of its parent, 2073 * which could have been changed by cpuset just after it inherits the 2074 * state from the parent and before it sits on the cgroup's task list. 2075 */ 2076 static void cpuset_fork(struct task_struct *task) 2077 { 2078 if (task_css_is_root(task, cpuset_cgrp_id)) 2079 return; 2080 2081 set_cpus_allowed_ptr(task, ¤t->cpus_allowed); 2082 task->mems_allowed = current->mems_allowed; 2083 } 2084 2085 struct cgroup_subsys cpuset_cgrp_subsys = { 2086 .css_alloc = cpuset_css_alloc, 2087 .css_online = cpuset_css_online, 2088 .css_offline = cpuset_css_offline, 2089 .css_free = cpuset_css_free, 2090 .can_attach = cpuset_can_attach, 2091 .cancel_attach = cpuset_cancel_attach, 2092 .attach = cpuset_attach, 2093 .post_attach = cpuset_post_attach, 2094 .bind = cpuset_bind, 2095 .fork = cpuset_fork, 2096 .legacy_cftypes = files, 2097 .early_init = true, 2098 }; 2099 2100 /** 2101 * cpuset_init - initialize cpusets at system boot 2102 * 2103 * Description: Initialize top_cpuset and the cpuset internal file system, 2104 **/ 2105 2106 int __init cpuset_init(void) 2107 { 2108 int err = 0; 2109 2110 BUG_ON(!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL)); 2111 BUG_ON(!alloc_cpumask_var(&top_cpuset.effective_cpus, GFP_KERNEL)); 2112 2113 cpumask_setall(top_cpuset.cpus_allowed); 2114 nodes_setall(top_cpuset.mems_allowed); 2115 cpumask_setall(top_cpuset.effective_cpus); 2116 nodes_setall(top_cpuset.effective_mems); 2117 2118 fmeter_init(&top_cpuset.fmeter); 2119 set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags); 2120 top_cpuset.relax_domain_level = -1; 2121 2122 err = register_filesystem(&cpuset_fs_type); 2123 if (err < 0) 2124 return err; 2125 2126 BUG_ON(!alloc_cpumask_var(&cpus_attach, GFP_KERNEL)); 2127 2128 return 0; 2129 } 2130 2131 /* 2132 * If CPU and/or memory hotplug handlers, below, unplug any CPUs 2133 * or memory nodes, we need to walk over the cpuset hierarchy, 2134 * removing that CPU or node from all cpusets. If this removes the 2135 * last CPU or node from a cpuset, then move the tasks in the empty 2136 * cpuset to its next-highest non-empty parent. 2137 */ 2138 static void remove_tasks_in_empty_cpuset(struct cpuset *cs) 2139 { 2140 struct cpuset *parent; 2141 2142 /* 2143 * Find its next-highest non-empty parent, (top cpuset 2144 * has online cpus, so can't be empty). 2145 */ 2146 parent = parent_cs(cs); 2147 while (cpumask_empty(parent->cpus_allowed) || 2148 nodes_empty(parent->mems_allowed)) 2149 parent = parent_cs(parent); 2150 2151 if (cgroup_transfer_tasks(parent->css.cgroup, cs->css.cgroup)) { 2152 pr_err("cpuset: failed to transfer tasks out of empty cpuset "); 2153 pr_cont_cgroup_name(cs->css.cgroup); 2154 pr_cont("\n"); 2155 } 2156 } 2157 2158 static void 2159 hotplug_update_tasks_legacy(struct cpuset *cs, 2160 struct cpumask *new_cpus, nodemask_t *new_mems, 2161 bool cpus_updated, bool mems_updated) 2162 { 2163 bool is_empty; 2164 2165 spin_lock_irq(&callback_lock); 2166 cpumask_copy(cs->cpus_allowed, new_cpus); 2167 cpumask_copy(cs->effective_cpus, new_cpus); 2168 cs->mems_allowed = *new_mems; 2169 cs->effective_mems = *new_mems; 2170 spin_unlock_irq(&callback_lock); 2171 2172 /* 2173 * Don't call update_tasks_cpumask() if the cpuset becomes empty, 2174 * as the tasks will be migratecd to an ancestor. 2175 */ 2176 if (cpus_updated && !cpumask_empty(cs->cpus_allowed)) 2177 update_tasks_cpumask(cs); 2178 if (mems_updated && !nodes_empty(cs->mems_allowed)) 2179 update_tasks_nodemask(cs); 2180 2181 is_empty = cpumask_empty(cs->cpus_allowed) || 2182 nodes_empty(cs->mems_allowed); 2183 2184 mutex_unlock(&cpuset_mutex); 2185 2186 /* 2187 * Move tasks to the nearest ancestor with execution resources, 2188 * This is full cgroup operation which will also call back into 2189 * cpuset. Should be done outside any lock. 2190 */ 2191 if (is_empty) 2192 remove_tasks_in_empty_cpuset(cs); 2193 2194 mutex_lock(&cpuset_mutex); 2195 } 2196 2197 static void 2198 hotplug_update_tasks(struct cpuset *cs, 2199 struct cpumask *new_cpus, nodemask_t *new_mems, 2200 bool cpus_updated, bool mems_updated) 2201 { 2202 if (cpumask_empty(new_cpus)) 2203 cpumask_copy(new_cpus, parent_cs(cs)->effective_cpus); 2204 if (nodes_empty(*new_mems)) 2205 *new_mems = parent_cs(cs)->effective_mems; 2206 2207 spin_lock_irq(&callback_lock); 2208 cpumask_copy(cs->effective_cpus, new_cpus); 2209 cs->effective_mems = *new_mems; 2210 spin_unlock_irq(&callback_lock); 2211 2212 if (cpus_updated) 2213 update_tasks_cpumask(cs); 2214 if (mems_updated) 2215 update_tasks_nodemask(cs); 2216 } 2217 2218 /** 2219 * cpuset_hotplug_update_tasks - update tasks in a cpuset for hotunplug 2220 * @cs: cpuset in interest 2221 * 2222 * Compare @cs's cpu and mem masks against top_cpuset and if some have gone 2223 * offline, update @cs accordingly. If @cs ends up with no CPU or memory, 2224 * all its tasks are moved to the nearest ancestor with both resources. 2225 */ 2226 static void cpuset_hotplug_update_tasks(struct cpuset *cs) 2227 { 2228 static cpumask_t new_cpus; 2229 static nodemask_t new_mems; 2230 bool cpus_updated; 2231 bool mems_updated; 2232 retry: 2233 wait_event(cpuset_attach_wq, cs->attach_in_progress == 0); 2234 2235 mutex_lock(&cpuset_mutex); 2236 2237 /* 2238 * We have raced with task attaching. We wait until attaching 2239 * is finished, so we won't attach a task to an empty cpuset. 2240 */ 2241 if (cs->attach_in_progress) { 2242 mutex_unlock(&cpuset_mutex); 2243 goto retry; 2244 } 2245 2246 cpumask_and(&new_cpus, cs->cpus_allowed, parent_cs(cs)->effective_cpus); 2247 nodes_and(new_mems, cs->mems_allowed, parent_cs(cs)->effective_mems); 2248 2249 cpus_updated = !cpumask_equal(&new_cpus, cs->effective_cpus); 2250 mems_updated = !nodes_equal(new_mems, cs->effective_mems); 2251 2252 if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys)) 2253 hotplug_update_tasks(cs, &new_cpus, &new_mems, 2254 cpus_updated, mems_updated); 2255 else 2256 hotplug_update_tasks_legacy(cs, &new_cpus, &new_mems, 2257 cpus_updated, mems_updated); 2258 2259 mutex_unlock(&cpuset_mutex); 2260 } 2261 2262 /** 2263 * cpuset_hotplug_workfn - handle CPU/memory hotunplug for a cpuset 2264 * 2265 * This function is called after either CPU or memory configuration has 2266 * changed and updates cpuset accordingly. The top_cpuset is always 2267 * synchronized to cpu_active_mask and N_MEMORY, which is necessary in 2268 * order to make cpusets transparent (of no affect) on systems that are 2269 * actively using CPU hotplug but making no active use of cpusets. 2270 * 2271 * Non-root cpusets are only affected by offlining. If any CPUs or memory 2272 * nodes have been taken down, cpuset_hotplug_update_tasks() is invoked on 2273 * all descendants. 2274 * 2275 * Note that CPU offlining during suspend is ignored. We don't modify 2276 * cpusets across suspend/resume cycles at all. 2277 */ 2278 static void cpuset_hotplug_workfn(struct work_struct *work) 2279 { 2280 static cpumask_t new_cpus; 2281 static nodemask_t new_mems; 2282 bool cpus_updated, mems_updated; 2283 bool on_dfl = cgroup_subsys_on_dfl(cpuset_cgrp_subsys); 2284 2285 mutex_lock(&cpuset_mutex); 2286 2287 /* fetch the available cpus/mems and find out which changed how */ 2288 cpumask_copy(&new_cpus, cpu_active_mask); 2289 new_mems = node_states[N_MEMORY]; 2290 2291 cpus_updated = !cpumask_equal(top_cpuset.effective_cpus, &new_cpus); 2292 mems_updated = !nodes_equal(top_cpuset.effective_mems, new_mems); 2293 2294 /* synchronize cpus_allowed to cpu_active_mask */ 2295 if (cpus_updated) { 2296 spin_lock_irq(&callback_lock); 2297 if (!on_dfl) 2298 cpumask_copy(top_cpuset.cpus_allowed, &new_cpus); 2299 cpumask_copy(top_cpuset.effective_cpus, &new_cpus); 2300 spin_unlock_irq(&callback_lock); 2301 /* we don't mess with cpumasks of tasks in top_cpuset */ 2302 } 2303 2304 /* synchronize mems_allowed to N_MEMORY */ 2305 if (mems_updated) { 2306 spin_lock_irq(&callback_lock); 2307 if (!on_dfl) 2308 top_cpuset.mems_allowed = new_mems; 2309 top_cpuset.effective_mems = new_mems; 2310 spin_unlock_irq(&callback_lock); 2311 update_tasks_nodemask(&top_cpuset); 2312 } 2313 2314 mutex_unlock(&cpuset_mutex); 2315 2316 /* if cpus or mems changed, we need to propagate to descendants */ 2317 if (cpus_updated || mems_updated) { 2318 struct cpuset *cs; 2319 struct cgroup_subsys_state *pos_css; 2320 2321 rcu_read_lock(); 2322 cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) { 2323 if (cs == &top_cpuset || !css_tryget_online(&cs->css)) 2324 continue; 2325 rcu_read_unlock(); 2326 2327 cpuset_hotplug_update_tasks(cs); 2328 2329 rcu_read_lock(); 2330 css_put(&cs->css); 2331 } 2332 rcu_read_unlock(); 2333 } 2334 2335 /* rebuild sched domains if cpus_allowed has changed */ 2336 if (cpus_updated) 2337 rebuild_sched_domains(); 2338 } 2339 2340 void cpuset_update_active_cpus(void) 2341 { 2342 /* 2343 * We're inside cpu hotplug critical region which usually nests 2344 * inside cgroup synchronization. Bounce actual hotplug processing 2345 * to a work item to avoid reverse locking order. 2346 * 2347 * We still need to do partition_sched_domains() synchronously; 2348 * otherwise, the scheduler will get confused and put tasks to the 2349 * dead CPU. Fall back to the default single domain. 2350 * cpuset_hotplug_workfn() will rebuild it as necessary. 2351 */ 2352 partition_sched_domains(1, NULL, NULL); 2353 schedule_work(&cpuset_hotplug_work); 2354 } 2355 2356 /* 2357 * Keep top_cpuset.mems_allowed tracking node_states[N_MEMORY]. 2358 * Call this routine anytime after node_states[N_MEMORY] changes. 2359 * See cpuset_update_active_cpus() for CPU hotplug handling. 2360 */ 2361 static int cpuset_track_online_nodes(struct notifier_block *self, 2362 unsigned long action, void *arg) 2363 { 2364 schedule_work(&cpuset_hotplug_work); 2365 return NOTIFY_OK; 2366 } 2367 2368 static struct notifier_block cpuset_track_online_nodes_nb = { 2369 .notifier_call = cpuset_track_online_nodes, 2370 .priority = 10, /* ??! */ 2371 }; 2372 2373 /** 2374 * cpuset_init_smp - initialize cpus_allowed 2375 * 2376 * Description: Finish top cpuset after cpu, node maps are initialized 2377 */ 2378 void __init cpuset_init_smp(void) 2379 { 2380 cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask); 2381 top_cpuset.mems_allowed = node_states[N_MEMORY]; 2382 top_cpuset.old_mems_allowed = top_cpuset.mems_allowed; 2383 2384 cpumask_copy(top_cpuset.effective_cpus, cpu_active_mask); 2385 top_cpuset.effective_mems = node_states[N_MEMORY]; 2386 2387 register_hotmemory_notifier(&cpuset_track_online_nodes_nb); 2388 2389 cpuset_migrate_mm_wq = alloc_ordered_workqueue("cpuset_migrate_mm", 0); 2390 BUG_ON(!cpuset_migrate_mm_wq); 2391 } 2392 2393 /** 2394 * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset. 2395 * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed. 2396 * @pmask: pointer to struct cpumask variable to receive cpus_allowed set. 2397 * 2398 * Description: Returns the cpumask_var_t cpus_allowed of the cpuset 2399 * attached to the specified @tsk. Guaranteed to return some non-empty 2400 * subset of cpu_online_mask, even if this means going outside the 2401 * tasks cpuset. 2402 **/ 2403 2404 void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask) 2405 { 2406 unsigned long flags; 2407 2408 spin_lock_irqsave(&callback_lock, flags); 2409 rcu_read_lock(); 2410 guarantee_online_cpus(task_cs(tsk), pmask); 2411 rcu_read_unlock(); 2412 spin_unlock_irqrestore(&callback_lock, flags); 2413 } 2414 2415 void cpuset_cpus_allowed_fallback(struct task_struct *tsk) 2416 { 2417 rcu_read_lock(); 2418 do_set_cpus_allowed(tsk, task_cs(tsk)->effective_cpus); 2419 rcu_read_unlock(); 2420 2421 /* 2422 * We own tsk->cpus_allowed, nobody can change it under us. 2423 * 2424 * But we used cs && cs->cpus_allowed lockless and thus can 2425 * race with cgroup_attach_task() or update_cpumask() and get 2426 * the wrong tsk->cpus_allowed. However, both cases imply the 2427 * subsequent cpuset_change_cpumask()->set_cpus_allowed_ptr() 2428 * which takes task_rq_lock(). 2429 * 2430 * If we are called after it dropped the lock we must see all 2431 * changes in tsk_cs()->cpus_allowed. Otherwise we can temporary 2432 * set any mask even if it is not right from task_cs() pov, 2433 * the pending set_cpus_allowed_ptr() will fix things. 2434 * 2435 * select_fallback_rq() will fix things ups and set cpu_possible_mask 2436 * if required. 2437 */ 2438 } 2439 2440 void __init cpuset_init_current_mems_allowed(void) 2441 { 2442 nodes_setall(current->mems_allowed); 2443 } 2444 2445 /** 2446 * cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset. 2447 * @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed. 2448 * 2449 * Description: Returns the nodemask_t mems_allowed of the cpuset 2450 * attached to the specified @tsk. Guaranteed to return some non-empty 2451 * subset of node_states[N_MEMORY], even if this means going outside the 2452 * tasks cpuset. 2453 **/ 2454 2455 nodemask_t cpuset_mems_allowed(struct task_struct *tsk) 2456 { 2457 nodemask_t mask; 2458 unsigned long flags; 2459 2460 spin_lock_irqsave(&callback_lock, flags); 2461 rcu_read_lock(); 2462 guarantee_online_mems(task_cs(tsk), &mask); 2463 rcu_read_unlock(); 2464 spin_unlock_irqrestore(&callback_lock, flags); 2465 2466 return mask; 2467 } 2468 2469 /** 2470 * cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed 2471 * @nodemask: the nodemask to be checked 2472 * 2473 * Are any of the nodes in the nodemask allowed in current->mems_allowed? 2474 */ 2475 int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask) 2476 { 2477 return nodes_intersects(*nodemask, current->mems_allowed); 2478 } 2479 2480 /* 2481 * nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or 2482 * mem_hardwall ancestor to the specified cpuset. Call holding 2483 * callback_lock. If no ancestor is mem_exclusive or mem_hardwall 2484 * (an unusual configuration), then returns the root cpuset. 2485 */ 2486 static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs) 2487 { 2488 while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && parent_cs(cs)) 2489 cs = parent_cs(cs); 2490 return cs; 2491 } 2492 2493 /** 2494 * cpuset_node_allowed - Can we allocate on a memory node? 2495 * @node: is this an allowed node? 2496 * @gfp_mask: memory allocation flags 2497 * 2498 * If we're in interrupt, yes, we can always allocate. If @node is set in 2499 * current's mems_allowed, yes. If it's not a __GFP_HARDWALL request and this 2500 * node is set in the nearest hardwalled cpuset ancestor to current's cpuset, 2501 * yes. If current has access to memory reserves due to TIF_MEMDIE, yes. 2502 * Otherwise, no. 2503 * 2504 * GFP_USER allocations are marked with the __GFP_HARDWALL bit, 2505 * and do not allow allocations outside the current tasks cpuset 2506 * unless the task has been OOM killed as is marked TIF_MEMDIE. 2507 * GFP_KERNEL allocations are not so marked, so can escape to the 2508 * nearest enclosing hardwalled ancestor cpuset. 2509 * 2510 * Scanning up parent cpusets requires callback_lock. The 2511 * __alloc_pages() routine only calls here with __GFP_HARDWALL bit 2512 * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the 2513 * current tasks mems_allowed came up empty on the first pass over 2514 * the zonelist. So only GFP_KERNEL allocations, if all nodes in the 2515 * cpuset are short of memory, might require taking the callback_lock. 2516 * 2517 * The first call here from mm/page_alloc:get_page_from_freelist() 2518 * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets, 2519 * so no allocation on a node outside the cpuset is allowed (unless 2520 * in interrupt, of course). 2521 * 2522 * The second pass through get_page_from_freelist() doesn't even call 2523 * here for GFP_ATOMIC calls. For those calls, the __alloc_pages() 2524 * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set 2525 * in alloc_flags. That logic and the checks below have the combined 2526 * affect that: 2527 * in_interrupt - any node ok (current task context irrelevant) 2528 * GFP_ATOMIC - any node ok 2529 * TIF_MEMDIE - any node ok 2530 * GFP_KERNEL - any node in enclosing hardwalled cpuset ok 2531 * GFP_USER - only nodes in current tasks mems allowed ok. 2532 */ 2533 bool __cpuset_node_allowed(int node, gfp_t gfp_mask) 2534 { 2535 struct cpuset *cs; /* current cpuset ancestors */ 2536 int allowed; /* is allocation in zone z allowed? */ 2537 unsigned long flags; 2538 2539 if (in_interrupt()) 2540 return true; 2541 if (node_isset(node, current->mems_allowed)) 2542 return true; 2543 /* 2544 * Allow tasks that have access to memory reserves because they have 2545 * been OOM killed to get memory anywhere. 2546 */ 2547 if (unlikely(test_thread_flag(TIF_MEMDIE))) 2548 return true; 2549 if (gfp_mask & __GFP_HARDWALL) /* If hardwall request, stop here */ 2550 return false; 2551 2552 if (current->flags & PF_EXITING) /* Let dying task have memory */ 2553 return true; 2554 2555 /* Not hardwall and node outside mems_allowed: scan up cpusets */ 2556 spin_lock_irqsave(&callback_lock, flags); 2557 2558 rcu_read_lock(); 2559 cs = nearest_hardwall_ancestor(task_cs(current)); 2560 allowed = node_isset(node, cs->mems_allowed); 2561 rcu_read_unlock(); 2562 2563 spin_unlock_irqrestore(&callback_lock, flags); 2564 return allowed; 2565 } 2566 2567 /** 2568 * cpuset_mem_spread_node() - On which node to begin search for a file page 2569 * cpuset_slab_spread_node() - On which node to begin search for a slab page 2570 * 2571 * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for 2572 * tasks in a cpuset with is_spread_page or is_spread_slab set), 2573 * and if the memory allocation used cpuset_mem_spread_node() 2574 * to determine on which node to start looking, as it will for 2575 * certain page cache or slab cache pages such as used for file 2576 * system buffers and inode caches, then instead of starting on the 2577 * local node to look for a free page, rather spread the starting 2578 * node around the tasks mems_allowed nodes. 2579 * 2580 * We don't have to worry about the returned node being offline 2581 * because "it can't happen", and even if it did, it would be ok. 2582 * 2583 * The routines calling guarantee_online_mems() are careful to 2584 * only set nodes in task->mems_allowed that are online. So it 2585 * should not be possible for the following code to return an 2586 * offline node. But if it did, that would be ok, as this routine 2587 * is not returning the node where the allocation must be, only 2588 * the node where the search should start. The zonelist passed to 2589 * __alloc_pages() will include all nodes. If the slab allocator 2590 * is passed an offline node, it will fall back to the local node. 2591 * See kmem_cache_alloc_node(). 2592 */ 2593 2594 static int cpuset_spread_node(int *rotor) 2595 { 2596 return *rotor = next_node_in(*rotor, current->mems_allowed); 2597 } 2598 2599 int cpuset_mem_spread_node(void) 2600 { 2601 if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE) 2602 current->cpuset_mem_spread_rotor = 2603 node_random(¤t->mems_allowed); 2604 2605 return cpuset_spread_node(¤t->cpuset_mem_spread_rotor); 2606 } 2607 2608 int cpuset_slab_spread_node(void) 2609 { 2610 if (current->cpuset_slab_spread_rotor == NUMA_NO_NODE) 2611 current->cpuset_slab_spread_rotor = 2612 node_random(¤t->mems_allowed); 2613 2614 return cpuset_spread_node(¤t->cpuset_slab_spread_rotor); 2615 } 2616 2617 EXPORT_SYMBOL_GPL(cpuset_mem_spread_node); 2618 2619 /** 2620 * cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's? 2621 * @tsk1: pointer to task_struct of some task. 2622 * @tsk2: pointer to task_struct of some other task. 2623 * 2624 * Description: Return true if @tsk1's mems_allowed intersects the 2625 * mems_allowed of @tsk2. Used by the OOM killer to determine if 2626 * one of the task's memory usage might impact the memory available 2627 * to the other. 2628 **/ 2629 2630 int cpuset_mems_allowed_intersects(const struct task_struct *tsk1, 2631 const struct task_struct *tsk2) 2632 { 2633 return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed); 2634 } 2635 2636 /** 2637 * cpuset_print_current_mems_allowed - prints current's cpuset and mems_allowed 2638 * 2639 * Description: Prints current's name, cpuset name, and cached copy of its 2640 * mems_allowed to the kernel log. 2641 */ 2642 void cpuset_print_current_mems_allowed(void) 2643 { 2644 struct cgroup *cgrp; 2645 2646 rcu_read_lock(); 2647 2648 cgrp = task_cs(current)->css.cgroup; 2649 pr_info("%s cpuset=", current->comm); 2650 pr_cont_cgroup_name(cgrp); 2651 pr_cont(" mems_allowed=%*pbl\n", 2652 nodemask_pr_args(¤t->mems_allowed)); 2653 2654 rcu_read_unlock(); 2655 } 2656 2657 /* 2658 * Collection of memory_pressure is suppressed unless 2659 * this flag is enabled by writing "1" to the special 2660 * cpuset file 'memory_pressure_enabled' in the root cpuset. 2661 */ 2662 2663 int cpuset_memory_pressure_enabled __read_mostly; 2664 2665 /** 2666 * cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims. 2667 * 2668 * Keep a running average of the rate of synchronous (direct) 2669 * page reclaim efforts initiated by tasks in each cpuset. 2670 * 2671 * This represents the rate at which some task in the cpuset 2672 * ran low on memory on all nodes it was allowed to use, and 2673 * had to enter the kernels page reclaim code in an effort to 2674 * create more free memory by tossing clean pages or swapping 2675 * or writing dirty pages. 2676 * 2677 * Display to user space in the per-cpuset read-only file 2678 * "memory_pressure". Value displayed is an integer 2679 * representing the recent rate of entry into the synchronous 2680 * (direct) page reclaim by any task attached to the cpuset. 2681 **/ 2682 2683 void __cpuset_memory_pressure_bump(void) 2684 { 2685 rcu_read_lock(); 2686 fmeter_markevent(&task_cs(current)->fmeter); 2687 rcu_read_unlock(); 2688 } 2689 2690 #ifdef CONFIG_PROC_PID_CPUSET 2691 /* 2692 * proc_cpuset_show() 2693 * - Print tasks cpuset path into seq_file. 2694 * - Used for /proc/<pid>/cpuset. 2695 * - No need to task_lock(tsk) on this tsk->cpuset reference, as it 2696 * doesn't really matter if tsk->cpuset changes after we read it, 2697 * and we take cpuset_mutex, keeping cpuset_attach() from changing it 2698 * anyway. 2699 */ 2700 int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns, 2701 struct pid *pid, struct task_struct *tsk) 2702 { 2703 char *buf; 2704 struct cgroup_subsys_state *css; 2705 int retval; 2706 2707 retval = -ENOMEM; 2708 buf = kmalloc(PATH_MAX, GFP_KERNEL); 2709 if (!buf) 2710 goto out; 2711 2712 css = task_get_css(tsk, cpuset_cgrp_id); 2713 retval = cgroup_path_ns(css->cgroup, buf, PATH_MAX, 2714 current->nsproxy->cgroup_ns); 2715 css_put(css); 2716 if (retval >= PATH_MAX) 2717 retval = -ENAMETOOLONG; 2718 if (retval < 0) 2719 goto out_free; 2720 seq_puts(m, buf); 2721 seq_putc(m, '\n'); 2722 retval = 0; 2723 out_free: 2724 kfree(buf); 2725 out: 2726 return retval; 2727 } 2728 #endif /* CONFIG_PROC_PID_CPUSET */ 2729 2730 /* Display task mems_allowed in /proc/<pid>/status file. */ 2731 void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task) 2732 { 2733 seq_printf(m, "Mems_allowed:\t%*pb\n", 2734 nodemask_pr_args(&task->mems_allowed)); 2735 seq_printf(m, "Mems_allowed_list:\t%*pbl\n", 2736 nodemask_pr_args(&task->mems_allowed)); 2737 } 2738