Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...
[sfrench/cifs-2.6.git] / kernel / sched / topology.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Scheduler topology setup/handling methods
4  */
5 #include "sched.h"
6
7 DEFINE_MUTEX(sched_domains_mutex);
8
9 /* Protected by sched_domains_mutex: */
10 cpumask_var_t sched_domains_tmpmask;
11 cpumask_var_t sched_domains_tmpmask2;
12
13 #ifdef CONFIG_SCHED_DEBUG
14
15 static int __init sched_debug_setup(char *str)
16 {
17         sched_debug_enabled = true;
18
19         return 0;
20 }
21 early_param("sched_debug", sched_debug_setup);
22
23 static inline bool sched_debug(void)
24 {
25         return sched_debug_enabled;
26 }
27
28 static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
29                                   struct cpumask *groupmask)
30 {
31         struct sched_group *group = sd->groups;
32
33         cpumask_clear(groupmask);
34
35         printk(KERN_DEBUG "%*s domain-%d: ", level, "", level);
36
37         if (!(sd->flags & SD_LOAD_BALANCE)) {
38                 printk("does not load-balance\n");
39                 if (sd->parent)
40                         printk(KERN_ERR "ERROR: !SD_LOAD_BALANCE domain has parent");
41                 return -1;
42         }
43
44         printk(KERN_CONT "span=%*pbl level=%s\n",
45                cpumask_pr_args(sched_domain_span(sd)), sd->name);
46
47         if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
48                 printk(KERN_ERR "ERROR: domain->span does not contain CPU%d\n", cpu);
49         }
50         if (!cpumask_test_cpu(cpu, sched_group_span(group))) {
51                 printk(KERN_ERR "ERROR: domain->groups does not contain CPU%d\n", cpu);
52         }
53
54         printk(KERN_DEBUG "%*s groups:", level + 1, "");
55         do {
56                 if (!group) {
57                         printk("\n");
58                         printk(KERN_ERR "ERROR: group is NULL\n");
59                         break;
60                 }
61
62                 if (!cpumask_weight(sched_group_span(group))) {
63                         printk(KERN_CONT "\n");
64                         printk(KERN_ERR "ERROR: empty group\n");
65                         break;
66                 }
67
68                 if (!(sd->flags & SD_OVERLAP) &&
69                     cpumask_intersects(groupmask, sched_group_span(group))) {
70                         printk(KERN_CONT "\n");
71                         printk(KERN_ERR "ERROR: repeated CPUs\n");
72                         break;
73                 }
74
75                 cpumask_or(groupmask, groupmask, sched_group_span(group));
76
77                 printk(KERN_CONT " %d:{ span=%*pbl",
78                                 group->sgc->id,
79                                 cpumask_pr_args(sched_group_span(group)));
80
81                 if ((sd->flags & SD_OVERLAP) &&
82                     !cpumask_equal(group_balance_mask(group), sched_group_span(group))) {
83                         printk(KERN_CONT " mask=%*pbl",
84                                 cpumask_pr_args(group_balance_mask(group)));
85                 }
86
87                 if (group->sgc->capacity != SCHED_CAPACITY_SCALE)
88                         printk(KERN_CONT " cap=%lu", group->sgc->capacity);
89
90                 if (group == sd->groups && sd->child &&
91                     !cpumask_equal(sched_domain_span(sd->child),
92                                    sched_group_span(group))) {
93                         printk(KERN_ERR "ERROR: domain->groups does not match domain->child\n");
94                 }
95
96                 printk(KERN_CONT " }");
97
98                 group = group->next;
99
100                 if (group != sd->groups)
101                         printk(KERN_CONT ",");
102
103         } while (group != sd->groups);
104         printk(KERN_CONT "\n");
105
106         if (!cpumask_equal(sched_domain_span(sd), groupmask))
107                 printk(KERN_ERR "ERROR: groups don't span domain->span\n");
108
109         if (sd->parent &&
110             !cpumask_subset(groupmask, sched_domain_span(sd->parent)))
111                 printk(KERN_ERR "ERROR: parent span is not a superset of domain->span\n");
112         return 0;
113 }
114
115 static void sched_domain_debug(struct sched_domain *sd, int cpu)
116 {
117         int level = 0;
118
119         if (!sched_debug_enabled)
120                 return;
121
122         if (!sd) {
123                 printk(KERN_DEBUG "CPU%d attaching NULL sched-domain.\n", cpu);
124                 return;
125         }
126
127         printk(KERN_DEBUG "CPU%d attaching sched-domain(s):\n", cpu);
128
129         for (;;) {
130                 if (sched_domain_debug_one(sd, cpu, level, sched_domains_tmpmask))
131                         break;
132                 level++;
133                 sd = sd->parent;
134                 if (!sd)
135                         break;
136         }
137 }
138 #else /* !CONFIG_SCHED_DEBUG */
139
140 # define sched_debug_enabled 0
141 # define sched_domain_debug(sd, cpu) do { } while (0)
142 static inline bool sched_debug(void)
143 {
144         return false;
145 }
146 #endif /* CONFIG_SCHED_DEBUG */
147
148 static int sd_degenerate(struct sched_domain *sd)
149 {
150         if (cpumask_weight(sched_domain_span(sd)) == 1)
151                 return 1;
152
153         /* Following flags need at least 2 groups */
154         if (sd->flags & (SD_LOAD_BALANCE |
155                          SD_BALANCE_NEWIDLE |
156                          SD_BALANCE_FORK |
157                          SD_BALANCE_EXEC |
158                          SD_SHARE_CPUCAPACITY |
159                          SD_ASYM_CPUCAPACITY |
160                          SD_SHARE_PKG_RESOURCES |
161                          SD_SHARE_POWERDOMAIN)) {
162                 if (sd->groups != sd->groups->next)
163                         return 0;
164         }
165
166         /* Following flags don't use groups */
167         if (sd->flags & (SD_WAKE_AFFINE))
168                 return 0;
169
170         return 1;
171 }
172
173 static int
174 sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
175 {
176         unsigned long cflags = sd->flags, pflags = parent->flags;
177
178         if (sd_degenerate(parent))
179                 return 1;
180
181         if (!cpumask_equal(sched_domain_span(sd), sched_domain_span(parent)))
182                 return 0;
183
184         /* Flags needing groups don't count if only 1 group in parent */
185         if (parent->groups == parent->groups->next) {
186                 pflags &= ~(SD_LOAD_BALANCE |
187                                 SD_BALANCE_NEWIDLE |
188                                 SD_BALANCE_FORK |
189                                 SD_BALANCE_EXEC |
190                                 SD_ASYM_CPUCAPACITY |
191                                 SD_SHARE_CPUCAPACITY |
192                                 SD_SHARE_PKG_RESOURCES |
193                                 SD_PREFER_SIBLING |
194                                 SD_SHARE_POWERDOMAIN);
195                 if (nr_node_ids == 1)
196                         pflags &= ~SD_SERIALIZE;
197         }
198         if (~cflags & pflags)
199                 return 0;
200
201         return 1;
202 }
203
204 static void free_rootdomain(struct rcu_head *rcu)
205 {
206         struct root_domain *rd = container_of(rcu, struct root_domain, rcu);
207
208         cpupri_cleanup(&rd->cpupri);
209         cpudl_cleanup(&rd->cpudl);
210         free_cpumask_var(rd->dlo_mask);
211         free_cpumask_var(rd->rto_mask);
212         free_cpumask_var(rd->online);
213         free_cpumask_var(rd->span);
214         kfree(rd);
215 }
216
217 void rq_attach_root(struct rq *rq, struct root_domain *rd)
218 {
219         struct root_domain *old_rd = NULL;
220         unsigned long flags;
221
222         raw_spin_lock_irqsave(&rq->lock, flags);
223
224         if (rq->rd) {
225                 old_rd = rq->rd;
226
227                 if (cpumask_test_cpu(rq->cpu, old_rd->online))
228                         set_rq_offline(rq);
229
230                 cpumask_clear_cpu(rq->cpu, old_rd->span);
231
232                 /*
233                  * If we dont want to free the old_rd yet then
234                  * set old_rd to NULL to skip the freeing later
235                  * in this function:
236                  */
237                 if (!atomic_dec_and_test(&old_rd->refcount))
238                         old_rd = NULL;
239         }
240
241         atomic_inc(&rd->refcount);
242         rq->rd = rd;
243
244         cpumask_set_cpu(rq->cpu, rd->span);
245         if (cpumask_test_cpu(rq->cpu, cpu_active_mask))
246                 set_rq_online(rq);
247
248         raw_spin_unlock_irqrestore(&rq->lock, flags);
249
250         if (old_rd)
251                 call_rcu_sched(&old_rd->rcu, free_rootdomain);
252 }
253
254 void sched_get_rd(struct root_domain *rd)
255 {
256         atomic_inc(&rd->refcount);
257 }
258
259 void sched_put_rd(struct root_domain *rd)
260 {
261         if (!atomic_dec_and_test(&rd->refcount))
262                 return;
263
264         call_rcu_sched(&rd->rcu, free_rootdomain);
265 }
266
267 static int init_rootdomain(struct root_domain *rd)
268 {
269         if (!zalloc_cpumask_var(&rd->span, GFP_KERNEL))
270                 goto out;
271         if (!zalloc_cpumask_var(&rd->online, GFP_KERNEL))
272                 goto free_span;
273         if (!zalloc_cpumask_var(&rd->dlo_mask, GFP_KERNEL))
274                 goto free_online;
275         if (!zalloc_cpumask_var(&rd->rto_mask, GFP_KERNEL))
276                 goto free_dlo_mask;
277
278 #ifdef HAVE_RT_PUSH_IPI
279         rd->rto_cpu = -1;
280         raw_spin_lock_init(&rd->rto_lock);
281         init_irq_work(&rd->rto_push_work, rto_push_irq_work_func);
282 #endif
283
284         init_dl_bw(&rd->dl_bw);
285         if (cpudl_init(&rd->cpudl) != 0)
286                 goto free_rto_mask;
287
288         if (cpupri_init(&rd->cpupri) != 0)
289                 goto free_cpudl;
290         return 0;
291
292 free_cpudl:
293         cpudl_cleanup(&rd->cpudl);
294 free_rto_mask:
295         free_cpumask_var(rd->rto_mask);
296 free_dlo_mask:
297         free_cpumask_var(rd->dlo_mask);
298 free_online:
299         free_cpumask_var(rd->online);
300 free_span:
301         free_cpumask_var(rd->span);
302 out:
303         return -ENOMEM;
304 }
305
306 /*
307  * By default the system creates a single root-domain with all CPUs as
308  * members (mimicking the global state we have today).
309  */
310 struct root_domain def_root_domain;
311
312 void init_defrootdomain(void)
313 {
314         init_rootdomain(&def_root_domain);
315
316         atomic_set(&def_root_domain.refcount, 1);
317 }
318
319 static struct root_domain *alloc_rootdomain(void)
320 {
321         struct root_domain *rd;
322
323         rd = kzalloc(sizeof(*rd), GFP_KERNEL);
324         if (!rd)
325                 return NULL;
326
327         if (init_rootdomain(rd) != 0) {
328                 kfree(rd);
329                 return NULL;
330         }
331
332         return rd;
333 }
334
335 static void free_sched_groups(struct sched_group *sg, int free_sgc)
336 {
337         struct sched_group *tmp, *first;
338
339         if (!sg)
340                 return;
341
342         first = sg;
343         do {
344                 tmp = sg->next;
345
346                 if (free_sgc && atomic_dec_and_test(&sg->sgc->ref))
347                         kfree(sg->sgc);
348
349                 if (atomic_dec_and_test(&sg->ref))
350                         kfree(sg);
351                 sg = tmp;
352         } while (sg != first);
353 }
354
355 static void destroy_sched_domain(struct sched_domain *sd)
356 {
357         /*
358          * A normal sched domain may have multiple group references, an
359          * overlapping domain, having private groups, only one.  Iterate,
360          * dropping group/capacity references, freeing where none remain.
361          */
362         free_sched_groups(sd->groups, 1);
363
364         if (sd->shared && atomic_dec_and_test(&sd->shared->ref))
365                 kfree(sd->shared);
366         kfree(sd);
367 }
368
369 static void destroy_sched_domains_rcu(struct rcu_head *rcu)
370 {
371         struct sched_domain *sd = container_of(rcu, struct sched_domain, rcu);
372
373         while (sd) {
374                 struct sched_domain *parent = sd->parent;
375                 destroy_sched_domain(sd);
376                 sd = parent;
377         }
378 }
379
380 static void destroy_sched_domains(struct sched_domain *sd)
381 {
382         if (sd)
383                 call_rcu(&sd->rcu, destroy_sched_domains_rcu);
384 }
385
386 /*
387  * Keep a special pointer to the highest sched_domain that has
388  * SD_SHARE_PKG_RESOURCE set (Last Level Cache Domain) for this
389  * allows us to avoid some pointer chasing select_idle_sibling().
390  *
391  * Also keep a unique ID per domain (we use the first CPU number in
392  * the cpumask of the domain), this allows us to quickly tell if
393  * two CPUs are in the same cache domain, see cpus_share_cache().
394  */
395 DEFINE_PER_CPU(struct sched_domain *, sd_llc);
396 DEFINE_PER_CPU(int, sd_llc_size);
397 DEFINE_PER_CPU(int, sd_llc_id);
398 DEFINE_PER_CPU(struct sched_domain_shared *, sd_llc_shared);
399 DEFINE_PER_CPU(struct sched_domain *, sd_numa);
400 DEFINE_PER_CPU(struct sched_domain *, sd_asym);
401
402 static void update_top_cache_domain(int cpu)
403 {
404         struct sched_domain_shared *sds = NULL;
405         struct sched_domain *sd;
406         int id = cpu;
407         int size = 1;
408
409         sd = highest_flag_domain(cpu, SD_SHARE_PKG_RESOURCES);
410         if (sd) {
411                 id = cpumask_first(sched_domain_span(sd));
412                 size = cpumask_weight(sched_domain_span(sd));
413                 sds = sd->shared;
414         }
415
416         rcu_assign_pointer(per_cpu(sd_llc, cpu), sd);
417         per_cpu(sd_llc_size, cpu) = size;
418         per_cpu(sd_llc_id, cpu) = id;
419         rcu_assign_pointer(per_cpu(sd_llc_shared, cpu), sds);
420
421         sd = lowest_flag_domain(cpu, SD_NUMA);
422         rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
423
424         sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
425         rcu_assign_pointer(per_cpu(sd_asym, cpu), sd);
426 }
427
428 /*
429  * Attach the domain 'sd' to 'cpu' as its base domain. Callers must
430  * hold the hotplug lock.
431  */
432 static void
433 cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
434 {
435         struct rq *rq = cpu_rq(cpu);
436         struct sched_domain *tmp;
437
438         /* Remove the sched domains which do not contribute to scheduling. */
439         for (tmp = sd; tmp; ) {
440                 struct sched_domain *parent = tmp->parent;
441                 if (!parent)
442                         break;
443
444                 if (sd_parent_degenerate(tmp, parent)) {
445                         tmp->parent = parent->parent;
446                         if (parent->parent)
447                                 parent->parent->child = tmp;
448                         /*
449                          * Transfer SD_PREFER_SIBLING down in case of a
450                          * degenerate parent; the spans match for this
451                          * so the property transfers.
452                          */
453                         if (parent->flags & SD_PREFER_SIBLING)
454                                 tmp->flags |= SD_PREFER_SIBLING;
455                         destroy_sched_domain(parent);
456                 } else
457                         tmp = tmp->parent;
458         }
459
460         if (sd && sd_degenerate(sd)) {
461                 tmp = sd;
462                 sd = sd->parent;
463                 destroy_sched_domain(tmp);
464                 if (sd)
465                         sd->child = NULL;
466         }
467
468         sched_domain_debug(sd, cpu);
469
470         rq_attach_root(rq, rd);
471         tmp = rq->sd;
472         rcu_assign_pointer(rq->sd, sd);
473         dirty_sched_domain_sysctl(cpu);
474         destroy_sched_domains(tmp);
475
476         update_top_cache_domain(cpu);
477 }
478
479 struct s_data {
480         struct sched_domain ** __percpu sd;
481         struct root_domain      *rd;
482 };
483
484 enum s_alloc {
485         sa_rootdomain,
486         sa_sd,
487         sa_sd_storage,
488         sa_none,
489 };
490
491 /*
492  * Return the canonical balance CPU for this group, this is the first CPU
493  * of this group that's also in the balance mask.
494  *
495  * The balance mask are all those CPUs that could actually end up at this
496  * group. See build_balance_mask().
497  *
498  * Also see should_we_balance().
499  */
500 int group_balance_cpu(struct sched_group *sg)
501 {
502         return cpumask_first(group_balance_mask(sg));
503 }
504
505
506 /*
507  * NUMA topology (first read the regular topology blurb below)
508  *
509  * Given a node-distance table, for example:
510  *
511  *   node   0   1   2   3
512  *     0:  10  20  30  20
513  *     1:  20  10  20  30
514  *     2:  30  20  10  20
515  *     3:  20  30  20  10
516  *
517  * which represents a 4 node ring topology like:
518  *
519  *   0 ----- 1
520  *   |       |
521  *   |       |
522  *   |       |
523  *   3 ----- 2
524  *
525  * We want to construct domains and groups to represent this. The way we go
526  * about doing this is to build the domains on 'hops'. For each NUMA level we
527  * construct the mask of all nodes reachable in @level hops.
528  *
529  * For the above NUMA topology that gives 3 levels:
530  *
531  * NUMA-2       0-3             0-3             0-3             0-3
532  *  groups:     {0-1,3},{1-3}   {0-2},{0,2-3}   {1-3},{0-1,3}   {0,2-3},{0-2}
533  *
534  * NUMA-1       0-1,3           0-2             1-3             0,2-3
535  *  groups:     {0},{1},{3}     {0},{1},{2}     {1},{2},{3}     {0},{2},{3}
536  *
537  * NUMA-0       0               1               2               3
538  *
539  *
540  * As can be seen; things don't nicely line up as with the regular topology.
541  * When we iterate a domain in child domain chunks some nodes can be
542  * represented multiple times -- hence the "overlap" naming for this part of
543  * the topology.
544  *
545  * In order to minimize this overlap, we only build enough groups to cover the
546  * domain. For instance Node-0 NUMA-2 would only get groups: 0-1,3 and 1-3.
547  *
548  * Because:
549  *
550  *  - the first group of each domain is its child domain; this
551  *    gets us the first 0-1,3
552  *  - the only uncovered node is 2, who's child domain is 1-3.
553  *
554  * However, because of the overlap, computing a unique CPU for each group is
555  * more complicated. Consider for instance the groups of NODE-1 NUMA-2, both
556  * groups include the CPUs of Node-0, while those CPUs would not in fact ever
557  * end up at those groups (they would end up in group: 0-1,3).
558  *
559  * To correct this we have to introduce the group balance mask. This mask
560  * will contain those CPUs in the group that can reach this group given the
561  * (child) domain tree.
562  *
563  * With this we can once again compute balance_cpu and sched_group_capacity
564  * relations.
565  *
566  * XXX include words on how balance_cpu is unique and therefore can be
567  * used for sched_group_capacity links.
568  *
569  *
570  * Another 'interesting' topology is:
571  *
572  *   node   0   1   2   3
573  *     0:  10  20  20  30
574  *     1:  20  10  20  20
575  *     2:  20  20  10  20
576  *     3:  30  20  20  10
577  *
578  * Which looks a little like:
579  *
580  *   0 ----- 1
581  *   |     / |
582  *   |   /   |
583  *   | /     |
584  *   2 ----- 3
585  *
586  * This topology is asymmetric, nodes 1,2 are fully connected, but nodes 0,3
587  * are not.
588  *
589  * This leads to a few particularly weird cases where the sched_domain's are
590  * not of the same number for each CPU. Consider:
591  *
592  * NUMA-2       0-3                                             0-3
593  *  groups:     {0-2},{1-3}                                     {1-3},{0-2}
594  *
595  * NUMA-1       0-2             0-3             0-3             1-3
596  *
597  * NUMA-0       0               1               2               3
598  *
599  */
600
601
602 /*
603  * Build the balance mask; it contains only those CPUs that can arrive at this
604  * group and should be considered to continue balancing.
605  *
606  * We do this during the group creation pass, therefore the group information
607  * isn't complete yet, however since each group represents a (child) domain we
608  * can fully construct this using the sched_domain bits (which are already
609  * complete).
610  */
611 static void
612 build_balance_mask(struct sched_domain *sd, struct sched_group *sg, struct cpumask *mask)
613 {
614         const struct cpumask *sg_span = sched_group_span(sg);
615         struct sd_data *sdd = sd->private;
616         struct sched_domain *sibling;
617         int i;
618
619         cpumask_clear(mask);
620
621         for_each_cpu(i, sg_span) {
622                 sibling = *per_cpu_ptr(sdd->sd, i);
623
624                 /*
625                  * Can happen in the asymmetric case, where these siblings are
626                  * unused. The mask will not be empty because those CPUs that
627                  * do have the top domain _should_ span the domain.
628                  */
629                 if (!sibling->child)
630                         continue;
631
632                 /* If we would not end up here, we can't continue from here */
633                 if (!cpumask_equal(sg_span, sched_domain_span(sibling->child)))
634                         continue;
635
636                 cpumask_set_cpu(i, mask);
637         }
638
639         /* We must not have empty masks here */
640         WARN_ON_ONCE(cpumask_empty(mask));
641 }
642
643 /*
644  * XXX: This creates per-node group entries; since the load-balancer will
645  * immediately access remote memory to construct this group's load-balance
646  * statistics having the groups node local is of dubious benefit.
647  */
648 static struct sched_group *
649 build_group_from_child_sched_domain(struct sched_domain *sd, int cpu)
650 {
651         struct sched_group *sg;
652         struct cpumask *sg_span;
653
654         sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
655                         GFP_KERNEL, cpu_to_node(cpu));
656
657         if (!sg)
658                 return NULL;
659
660         sg_span = sched_group_span(sg);
661         if (sd->child)
662                 cpumask_copy(sg_span, sched_domain_span(sd->child));
663         else
664                 cpumask_copy(sg_span, sched_domain_span(sd));
665
666         atomic_inc(&sg->ref);
667         return sg;
668 }
669
670 static void init_overlap_sched_group(struct sched_domain *sd,
671                                      struct sched_group *sg)
672 {
673         struct cpumask *mask = sched_domains_tmpmask2;
674         struct sd_data *sdd = sd->private;
675         struct cpumask *sg_span;
676         int cpu;
677
678         build_balance_mask(sd, sg, mask);
679         cpu = cpumask_first_and(sched_group_span(sg), mask);
680
681         sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
682         if (atomic_inc_return(&sg->sgc->ref) == 1)
683                 cpumask_copy(group_balance_mask(sg), mask);
684         else
685                 WARN_ON_ONCE(!cpumask_equal(group_balance_mask(sg), mask));
686
687         /*
688          * Initialize sgc->capacity such that even if we mess up the
689          * domains and no possible iteration will get us here, we won't
690          * die on a /0 trap.
691          */
692         sg_span = sched_group_span(sg);
693         sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
694         sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
695 }
696
697 static int
698 build_overlap_sched_groups(struct sched_domain *sd, int cpu)
699 {
700         struct sched_group *first = NULL, *last = NULL, *sg;
701         const struct cpumask *span = sched_domain_span(sd);
702         struct cpumask *covered = sched_domains_tmpmask;
703         struct sd_data *sdd = sd->private;
704         struct sched_domain *sibling;
705         int i;
706
707         cpumask_clear(covered);
708
709         for_each_cpu_wrap(i, span, cpu) {
710                 struct cpumask *sg_span;
711
712                 if (cpumask_test_cpu(i, covered))
713                         continue;
714
715                 sibling = *per_cpu_ptr(sdd->sd, i);
716
717                 /*
718                  * Asymmetric node setups can result in situations where the
719                  * domain tree is of unequal depth, make sure to skip domains
720                  * that already cover the entire range.
721                  *
722                  * In that case build_sched_domains() will have terminated the
723                  * iteration early and our sibling sd spans will be empty.
724                  * Domains should always include the CPU they're built on, so
725                  * check that.
726                  */
727                 if (!cpumask_test_cpu(i, sched_domain_span(sibling)))
728                         continue;
729
730                 sg = build_group_from_child_sched_domain(sibling, cpu);
731                 if (!sg)
732                         goto fail;
733
734                 sg_span = sched_group_span(sg);
735                 cpumask_or(covered, covered, sg_span);
736
737                 init_overlap_sched_group(sd, sg);
738
739                 if (!first)
740                         first = sg;
741                 if (last)
742                         last->next = sg;
743                 last = sg;
744                 last->next = first;
745         }
746         sd->groups = first;
747
748         return 0;
749
750 fail:
751         free_sched_groups(first, 0);
752
753         return -ENOMEM;
754 }
755
756
757 /*
758  * Package topology (also see the load-balance blurb in fair.c)
759  *
760  * The scheduler builds a tree structure to represent a number of important
761  * topology features. By default (default_topology[]) these include:
762  *
763  *  - Simultaneous multithreading (SMT)
764  *  - Multi-Core Cache (MC)
765  *  - Package (DIE)
766  *
767  * Where the last one more or less denotes everything up to a NUMA node.
768  *
769  * The tree consists of 3 primary data structures:
770  *
771  *      sched_domain -> sched_group -> sched_group_capacity
772  *          ^ ^             ^ ^
773  *          `-'             `-'
774  *
775  * The sched_domains are per-CPU and have a two way link (parent & child) and
776  * denote the ever growing mask of CPUs belonging to that level of topology.
777  *
778  * Each sched_domain has a circular (double) linked list of sched_group's, each
779  * denoting the domains of the level below (or individual CPUs in case of the
780  * first domain level). The sched_group linked by a sched_domain includes the
781  * CPU of that sched_domain [*].
782  *
783  * Take for instance a 2 threaded, 2 core, 2 cache cluster part:
784  *
785  * CPU   0   1   2   3   4   5   6   7
786  *
787  * DIE  [                             ]
788  * MC   [             ] [             ]
789  * SMT  [     ] [     ] [     ] [     ]
790  *
791  *  - or -
792  *
793  * DIE  0-7 0-7 0-7 0-7 0-7 0-7 0-7 0-7
794  * MC   0-3 0-3 0-3 0-3 4-7 4-7 4-7 4-7
795  * SMT  0-1 0-1 2-3 2-3 4-5 4-5 6-7 6-7
796  *
797  * CPU   0   1   2   3   4   5   6   7
798  *
799  * One way to think about it is: sched_domain moves you up and down among these
800  * topology levels, while sched_group moves you sideways through it, at child
801  * domain granularity.
802  *
803  * sched_group_capacity ensures each unique sched_group has shared storage.
804  *
805  * There are two related construction problems, both require a CPU that
806  * uniquely identify each group (for a given domain):
807  *
808  *  - The first is the balance_cpu (see should_we_balance() and the
809  *    load-balance blub in fair.c); for each group we only want 1 CPU to
810  *    continue balancing at a higher domain.
811  *
812  *  - The second is the sched_group_capacity; we want all identical groups
813  *    to share a single sched_group_capacity.
814  *
815  * Since these topologies are exclusive by construction. That is, its
816  * impossible for an SMT thread to belong to multiple cores, and cores to
817  * be part of multiple caches. There is a very clear and unique location
818  * for each CPU in the hierarchy.
819  *
820  * Therefore computing a unique CPU for each group is trivial (the iteration
821  * mask is redundant and set all 1s; all CPUs in a group will end up at _that_
822  * group), we can simply pick the first CPU in each group.
823  *
824  *
825  * [*] in other words, the first group of each domain is its child domain.
826  */
827
828 static struct sched_group *get_group(int cpu, struct sd_data *sdd)
829 {
830         struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
831         struct sched_domain *child = sd->child;
832         struct sched_group *sg;
833
834         if (child)
835                 cpu = cpumask_first(sched_domain_span(child));
836
837         sg = *per_cpu_ptr(sdd->sg, cpu);
838         sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
839
840         /* For claim_allocations: */
841         atomic_inc(&sg->ref);
842         atomic_inc(&sg->sgc->ref);
843
844         if (child) {
845                 cpumask_copy(sched_group_span(sg), sched_domain_span(child));
846                 cpumask_copy(group_balance_mask(sg), sched_group_span(sg));
847         } else {
848                 cpumask_set_cpu(cpu, sched_group_span(sg));
849                 cpumask_set_cpu(cpu, group_balance_mask(sg));
850         }
851
852         sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sched_group_span(sg));
853         sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
854
855         return sg;
856 }
857
858 /*
859  * build_sched_groups will build a circular linked list of the groups
860  * covered by the given span, and will set each group's ->cpumask correctly,
861  * and ->cpu_capacity to 0.
862  *
863  * Assumes the sched_domain tree is fully constructed
864  */
865 static int
866 build_sched_groups(struct sched_domain *sd, int cpu)
867 {
868         struct sched_group *first = NULL, *last = NULL;
869         struct sd_data *sdd = sd->private;
870         const struct cpumask *span = sched_domain_span(sd);
871         struct cpumask *covered;
872         int i;
873
874         lockdep_assert_held(&sched_domains_mutex);
875         covered = sched_domains_tmpmask;
876
877         cpumask_clear(covered);
878
879         for_each_cpu_wrap(i, span, cpu) {
880                 struct sched_group *sg;
881
882                 if (cpumask_test_cpu(i, covered))
883                         continue;
884
885                 sg = get_group(i, sdd);
886
887                 cpumask_or(covered, covered, sched_group_span(sg));
888
889                 if (!first)
890                         first = sg;
891                 if (last)
892                         last->next = sg;
893                 last = sg;
894         }
895         last->next = first;
896         sd->groups = first;
897
898         return 0;
899 }
900
901 /*
902  * Initialize sched groups cpu_capacity.
903  *
904  * cpu_capacity indicates the capacity of sched group, which is used while
905  * distributing the load between different sched groups in a sched domain.
906  * Typically cpu_capacity for all the groups in a sched domain will be same
907  * unless there are asymmetries in the topology. If there are asymmetries,
908  * group having more cpu_capacity will pickup more load compared to the
909  * group having less cpu_capacity.
910  */
911 static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
912 {
913         struct sched_group *sg = sd->groups;
914
915         WARN_ON(!sg);
916
917         do {
918                 int cpu, max_cpu = -1;
919
920                 sg->group_weight = cpumask_weight(sched_group_span(sg));
921
922                 if (!(sd->flags & SD_ASYM_PACKING))
923                         goto next;
924
925                 for_each_cpu(cpu, sched_group_span(sg)) {
926                         if (max_cpu < 0)
927                                 max_cpu = cpu;
928                         else if (sched_asym_prefer(cpu, max_cpu))
929                                 max_cpu = cpu;
930                 }
931                 sg->asym_prefer_cpu = max_cpu;
932
933 next:
934                 sg = sg->next;
935         } while (sg != sd->groups);
936
937         if (cpu != group_balance_cpu(sg))
938                 return;
939
940         update_group_capacity(sd, cpu);
941 }
942
943 /*
944  * Initializers for schedule domains
945  * Non-inlined to reduce accumulated stack pressure in build_sched_domains()
946  */
947
948 static int default_relax_domain_level = -1;
949 int sched_domain_level_max;
950
951 static int __init setup_relax_domain_level(char *str)
952 {
953         if (kstrtoint(str, 0, &default_relax_domain_level))
954                 pr_warn("Unable to set relax_domain_level\n");
955
956         return 1;
957 }
958 __setup("relax_domain_level=", setup_relax_domain_level);
959
960 static void set_domain_attribute(struct sched_domain *sd,
961                                  struct sched_domain_attr *attr)
962 {
963         int request;
964
965         if (!attr || attr->relax_domain_level < 0) {
966                 if (default_relax_domain_level < 0)
967                         return;
968                 else
969                         request = default_relax_domain_level;
970         } else
971                 request = attr->relax_domain_level;
972         if (request < sd->level) {
973                 /* Turn off idle balance on this domain: */
974                 sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
975         } else {
976                 /* Turn on idle balance on this domain: */
977                 sd->flags |= (SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
978         }
979 }
980
981 static void __sdt_free(const struct cpumask *cpu_map);
982 static int __sdt_alloc(const struct cpumask *cpu_map);
983
984 static void __free_domain_allocs(struct s_data *d, enum s_alloc what,
985                                  const struct cpumask *cpu_map)
986 {
987         switch (what) {
988         case sa_rootdomain:
989                 if (!atomic_read(&d->rd->refcount))
990                         free_rootdomain(&d->rd->rcu);
991                 /* Fall through */
992         case sa_sd:
993                 free_percpu(d->sd);
994                 /* Fall through */
995         case sa_sd_storage:
996                 __sdt_free(cpu_map);
997                 /* Fall through */
998         case sa_none:
999                 break;
1000         }
1001 }
1002
1003 static enum s_alloc
1004 __visit_domain_allocation_hell(struct s_data *d, const struct cpumask *cpu_map)
1005 {
1006         memset(d, 0, sizeof(*d));
1007
1008         if (__sdt_alloc(cpu_map))
1009                 return sa_sd_storage;
1010         d->sd = alloc_percpu(struct sched_domain *);
1011         if (!d->sd)
1012                 return sa_sd_storage;
1013         d->rd = alloc_rootdomain();
1014         if (!d->rd)
1015                 return sa_sd;
1016
1017         return sa_rootdomain;
1018 }
1019
1020 /*
1021  * NULL the sd_data elements we've used to build the sched_domain and
1022  * sched_group structure so that the subsequent __free_domain_allocs()
1023  * will not free the data we're using.
1024  */
1025 static void claim_allocations(int cpu, struct sched_domain *sd)
1026 {
1027         struct sd_data *sdd = sd->private;
1028
1029         WARN_ON_ONCE(*per_cpu_ptr(sdd->sd, cpu) != sd);
1030         *per_cpu_ptr(sdd->sd, cpu) = NULL;
1031
1032         if (atomic_read(&(*per_cpu_ptr(sdd->sds, cpu))->ref))
1033                 *per_cpu_ptr(sdd->sds, cpu) = NULL;
1034
1035         if (atomic_read(&(*per_cpu_ptr(sdd->sg, cpu))->ref))
1036                 *per_cpu_ptr(sdd->sg, cpu) = NULL;
1037
1038         if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
1039                 *per_cpu_ptr(sdd->sgc, cpu) = NULL;
1040 }
1041
1042 #ifdef CONFIG_NUMA
1043 enum numa_topology_type sched_numa_topology_type;
1044
1045 static int                      sched_domains_numa_levels;
1046 static int                      sched_domains_curr_level;
1047
1048 int                             sched_max_numa_distance;
1049 static int                      *sched_domains_numa_distance;
1050 static struct cpumask           ***sched_domains_numa_masks;
1051 #endif
1052
1053 /*
1054  * SD_flags allowed in topology descriptions.
1055  *
1056  * These flags are purely descriptive of the topology and do not prescribe
1057  * behaviour. Behaviour is artificial and mapped in the below sd_init()
1058  * function:
1059  *
1060  *   SD_SHARE_CPUCAPACITY   - describes SMT topologies
1061  *   SD_SHARE_PKG_RESOURCES - describes shared caches
1062  *   SD_NUMA                - describes NUMA topologies
1063  *   SD_SHARE_POWERDOMAIN   - describes shared power domain
1064  *   SD_ASYM_CPUCAPACITY    - describes mixed capacity topologies
1065  *
1066  * Odd one out, which beside describing the topology has a quirk also
1067  * prescribes the desired behaviour that goes along with it:
1068  *
1069  *   SD_ASYM_PACKING        - describes SMT quirks
1070  */
1071 #define TOPOLOGY_SD_FLAGS               \
1072         (SD_SHARE_CPUCAPACITY   |       \
1073          SD_SHARE_PKG_RESOURCES |       \
1074          SD_NUMA                |       \
1075          SD_ASYM_PACKING        |       \
1076          SD_ASYM_CPUCAPACITY    |       \
1077          SD_SHARE_POWERDOMAIN)
1078
1079 static struct sched_domain *
1080 sd_init(struct sched_domain_topology_level *tl,
1081         const struct cpumask *cpu_map,
1082         struct sched_domain *child, int cpu)
1083 {
1084         struct sd_data *sdd = &tl->data;
1085         struct sched_domain *sd = *per_cpu_ptr(sdd->sd, cpu);
1086         int sd_id, sd_weight, sd_flags = 0;
1087
1088 #ifdef CONFIG_NUMA
1089         /*
1090          * Ugly hack to pass state to sd_numa_mask()...
1091          */
1092         sched_domains_curr_level = tl->numa_level;
1093 #endif
1094
1095         sd_weight = cpumask_weight(tl->mask(cpu));
1096
1097         if (tl->sd_flags)
1098                 sd_flags = (*tl->sd_flags)();
1099         if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS,
1100                         "wrong sd_flags in topology description\n"))
1101                 sd_flags &= ~TOPOLOGY_SD_FLAGS;
1102
1103         *sd = (struct sched_domain){
1104                 .min_interval           = sd_weight,
1105                 .max_interval           = 2*sd_weight,
1106                 .busy_factor            = 32,
1107                 .imbalance_pct          = 125,
1108
1109                 .cache_nice_tries       = 0,
1110                 .busy_idx               = 0,
1111                 .idle_idx               = 0,
1112                 .newidle_idx            = 0,
1113                 .wake_idx               = 0,
1114                 .forkexec_idx           = 0,
1115
1116                 .flags                  = 1*SD_LOAD_BALANCE
1117                                         | 1*SD_BALANCE_NEWIDLE
1118                                         | 1*SD_BALANCE_EXEC
1119                                         | 1*SD_BALANCE_FORK
1120                                         | 0*SD_BALANCE_WAKE
1121                                         | 1*SD_WAKE_AFFINE
1122                                         | 0*SD_SHARE_CPUCAPACITY
1123                                         | 0*SD_SHARE_PKG_RESOURCES
1124                                         | 0*SD_SERIALIZE
1125                                         | 0*SD_PREFER_SIBLING
1126                                         | 0*SD_NUMA
1127                                         | sd_flags
1128                                         ,
1129
1130                 .last_balance           = jiffies,
1131                 .balance_interval       = sd_weight,
1132                 .smt_gain               = 0,
1133                 .max_newidle_lb_cost    = 0,
1134                 .next_decay_max_lb_cost = jiffies,
1135                 .child                  = child,
1136 #ifdef CONFIG_SCHED_DEBUG
1137                 .name                   = tl->name,
1138 #endif
1139         };
1140
1141         cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu));
1142         sd_id = cpumask_first(sched_domain_span(sd));
1143
1144         /*
1145          * Convert topological properties into behaviour.
1146          */
1147
1148         if (sd->flags & SD_ASYM_CPUCAPACITY) {
1149                 struct sched_domain *t = sd;
1150
1151                 for_each_lower_domain(t)
1152                         t->flags |= SD_BALANCE_WAKE;
1153         }
1154
1155         if (sd->flags & SD_SHARE_CPUCAPACITY) {
1156                 sd->flags |= SD_PREFER_SIBLING;
1157                 sd->imbalance_pct = 110;
1158                 sd->smt_gain = 1178; /* ~15% */
1159
1160         } else if (sd->flags & SD_SHARE_PKG_RESOURCES) {
1161                 sd->flags |= SD_PREFER_SIBLING;
1162                 sd->imbalance_pct = 117;
1163                 sd->cache_nice_tries = 1;
1164                 sd->busy_idx = 2;
1165
1166 #ifdef CONFIG_NUMA
1167         } else if (sd->flags & SD_NUMA) {
1168                 sd->cache_nice_tries = 2;
1169                 sd->busy_idx = 3;
1170                 sd->idle_idx = 2;
1171
1172                 sd->flags |= SD_SERIALIZE;
1173                 if (sched_domains_numa_distance[tl->numa_level] > RECLAIM_DISTANCE) {
1174                         sd->flags &= ~(SD_BALANCE_EXEC |
1175                                        SD_BALANCE_FORK |
1176                                        SD_WAKE_AFFINE);
1177                 }
1178
1179 #endif
1180         } else {
1181                 sd->flags |= SD_PREFER_SIBLING;
1182                 sd->cache_nice_tries = 1;
1183                 sd->busy_idx = 2;
1184                 sd->idle_idx = 1;
1185         }
1186
1187         /*
1188          * For all levels sharing cache; connect a sched_domain_shared
1189          * instance.
1190          */
1191         if (sd->flags & SD_SHARE_PKG_RESOURCES) {
1192                 sd->shared = *per_cpu_ptr(sdd->sds, sd_id);
1193                 atomic_inc(&sd->shared->ref);
1194                 atomic_set(&sd->shared->nr_busy_cpus, sd_weight);
1195         }
1196
1197         sd->private = sdd;
1198
1199         return sd;
1200 }
1201
1202 /*
1203  * Topology list, bottom-up.
1204  */
1205 static struct sched_domain_topology_level default_topology[] = {
1206 #ifdef CONFIG_SCHED_SMT
1207         { cpu_smt_mask, cpu_smt_flags, SD_INIT_NAME(SMT) },
1208 #endif
1209 #ifdef CONFIG_SCHED_MC
1210         { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
1211 #endif
1212         { cpu_cpu_mask, SD_INIT_NAME(DIE) },
1213         { NULL, },
1214 };
1215
1216 static struct sched_domain_topology_level *sched_domain_topology =
1217         default_topology;
1218
1219 #define for_each_sd_topology(tl)                        \
1220         for (tl = sched_domain_topology; tl->mask; tl++)
1221
1222 void set_sched_topology(struct sched_domain_topology_level *tl)
1223 {
1224         if (WARN_ON_ONCE(sched_smp_initialized))
1225                 return;
1226
1227         sched_domain_topology = tl;
1228 }
1229
1230 #ifdef CONFIG_NUMA
1231
1232 static const struct cpumask *sd_numa_mask(int cpu)
1233 {
1234         return sched_domains_numa_masks[sched_domains_curr_level][cpu_to_node(cpu)];
1235 }
1236
1237 static void sched_numa_warn(const char *str)
1238 {
1239         static int done = false;
1240         int i,j;
1241
1242         if (done)
1243                 return;
1244
1245         done = true;
1246
1247         printk(KERN_WARNING "ERROR: %s\n\n", str);
1248
1249         for (i = 0; i < nr_node_ids; i++) {
1250                 printk(KERN_WARNING "  ");
1251                 for (j = 0; j < nr_node_ids; j++)
1252                         printk(KERN_CONT "%02d ", node_distance(i,j));
1253                 printk(KERN_CONT "\n");
1254         }
1255         printk(KERN_WARNING "\n");
1256 }
1257
1258 bool find_numa_distance(int distance)
1259 {
1260         int i;
1261
1262         if (distance == node_distance(0, 0))
1263                 return true;
1264
1265         for (i = 0; i < sched_domains_numa_levels; i++) {
1266                 if (sched_domains_numa_distance[i] == distance)
1267                         return true;
1268         }
1269
1270         return false;
1271 }
1272
1273 /*
1274  * A system can have three types of NUMA topology:
1275  * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
1276  * NUMA_GLUELESS_MESH: some nodes reachable through intermediary nodes
1277  * NUMA_BACKPLANE: nodes can reach other nodes through a backplane
1278  *
1279  * The difference between a glueless mesh topology and a backplane
1280  * topology lies in whether communication between not directly
1281  * connected nodes goes through intermediary nodes (where programs
1282  * could run), or through backplane controllers. This affects
1283  * placement of programs.
1284  *
1285  * The type of topology can be discerned with the following tests:
1286  * - If the maximum distance between any nodes is 1 hop, the system
1287  *   is directly connected.
1288  * - If for two nodes A and B, located N > 1 hops away from each other,
1289  *   there is an intermediary node C, which is < N hops away from both
1290  *   nodes A and B, the system is a glueless mesh.
1291  */
1292 static void init_numa_topology_type(void)
1293 {
1294         int a, b, c, n;
1295
1296         n = sched_max_numa_distance;
1297
1298         if (sched_domains_numa_levels <= 1) {
1299                 sched_numa_topology_type = NUMA_DIRECT;
1300                 return;
1301         }
1302
1303         for_each_online_node(a) {
1304                 for_each_online_node(b) {
1305                         /* Find two nodes furthest removed from each other. */
1306                         if (node_distance(a, b) < n)
1307                                 continue;
1308
1309                         /* Is there an intermediary node between a and b? */
1310                         for_each_online_node(c) {
1311                                 if (node_distance(a, c) < n &&
1312                                     node_distance(b, c) < n) {
1313                                         sched_numa_topology_type =
1314                                                         NUMA_GLUELESS_MESH;
1315                                         return;
1316                                 }
1317                         }
1318
1319                         sched_numa_topology_type = NUMA_BACKPLANE;
1320                         return;
1321                 }
1322         }
1323 }
1324
1325 void sched_init_numa(void)
1326 {
1327         int next_distance, curr_distance = node_distance(0, 0);
1328         struct sched_domain_topology_level *tl;
1329         int level = 0;
1330         int i, j, k;
1331
1332         sched_domains_numa_distance = kzalloc(sizeof(int) * nr_node_ids, GFP_KERNEL);
1333         if (!sched_domains_numa_distance)
1334                 return;
1335
1336         /* Includes NUMA identity node at level 0. */
1337         sched_domains_numa_distance[level++] = curr_distance;
1338         sched_domains_numa_levels = level;
1339
1340         /*
1341          * O(nr_nodes^2) deduplicating selection sort -- in order to find the
1342          * unique distances in the node_distance() table.
1343          *
1344          * Assumes node_distance(0,j) includes all distances in
1345          * node_distance(i,j) in order to avoid cubic time.
1346          */
1347         next_distance = curr_distance;
1348         for (i = 0; i < nr_node_ids; i++) {
1349                 for (j = 0; j < nr_node_ids; j++) {
1350                         for (k = 0; k < nr_node_ids; k++) {
1351                                 int distance = node_distance(i, k);
1352
1353                                 if (distance > curr_distance &&
1354                                     (distance < next_distance ||
1355                                      next_distance == curr_distance))
1356                                         next_distance = distance;
1357
1358                                 /*
1359                                  * While not a strong assumption it would be nice to know
1360                                  * about cases where if node A is connected to B, B is not
1361                                  * equally connected to A.
1362                                  */
1363                                 if (sched_debug() && node_distance(k, i) != distance)
1364                                         sched_numa_warn("Node-distance not symmetric");
1365
1366                                 if (sched_debug() && i && !find_numa_distance(distance))
1367                                         sched_numa_warn("Node-0 not representative");
1368                         }
1369                         if (next_distance != curr_distance) {
1370                                 sched_domains_numa_distance[level++] = next_distance;
1371                                 sched_domains_numa_levels = level;
1372                                 curr_distance = next_distance;
1373                         } else break;
1374                 }
1375
1376                 /*
1377                  * In case of sched_debug() we verify the above assumption.
1378                  */
1379                 if (!sched_debug())
1380                         break;
1381         }
1382
1383         if (!level)
1384                 return;
1385
1386         /*
1387          * 'level' contains the number of unique distances
1388          *
1389          * The sched_domains_numa_distance[] array includes the actual distance
1390          * numbers.
1391          */
1392
1393         /*
1394          * Here, we should temporarily reset sched_domains_numa_levels to 0.
1395          * If it fails to allocate memory for array sched_domains_numa_masks[][],
1396          * the array will contain less then 'level' members. This could be
1397          * dangerous when we use it to iterate array sched_domains_numa_masks[][]
1398          * in other functions.
1399          *
1400          * We reset it to 'level' at the end of this function.
1401          */
1402         sched_domains_numa_levels = 0;
1403
1404         sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL);
1405         if (!sched_domains_numa_masks)
1406                 return;
1407
1408         /*
1409          * Now for each level, construct a mask per node which contains all
1410          * CPUs of nodes that are that many hops away from us.
1411          */
1412         for (i = 0; i < level; i++) {
1413                 sched_domains_numa_masks[i] =
1414                         kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
1415                 if (!sched_domains_numa_masks[i])
1416                         return;
1417
1418                 for (j = 0; j < nr_node_ids; j++) {
1419                         struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
1420                         if (!mask)
1421                                 return;
1422
1423                         sched_domains_numa_masks[i][j] = mask;
1424
1425                         for_each_node(k) {
1426                                 if (node_distance(j, k) > sched_domains_numa_distance[i])
1427                                         continue;
1428
1429                                 cpumask_or(mask, mask, cpumask_of_node(k));
1430                         }
1431                 }
1432         }
1433
1434         /* Compute default topology size */
1435         for (i = 0; sched_domain_topology[i].mask; i++);
1436
1437         tl = kzalloc((i + level + 1) *
1438                         sizeof(struct sched_domain_topology_level), GFP_KERNEL);
1439         if (!tl)
1440                 return;
1441
1442         /*
1443          * Copy the default topology bits..
1444          */
1445         for (i = 0; sched_domain_topology[i].mask; i++)
1446                 tl[i] = sched_domain_topology[i];
1447
1448         /*
1449          * Add the NUMA identity distance, aka single NODE.
1450          */
1451         tl[i++] = (struct sched_domain_topology_level){
1452                 .mask = sd_numa_mask,
1453                 .numa_level = 0,
1454                 SD_INIT_NAME(NODE)
1455         };
1456
1457         /*
1458          * .. and append 'j' levels of NUMA goodness.
1459          */
1460         for (j = 1; j < level; i++, j++) {
1461                 tl[i] = (struct sched_domain_topology_level){
1462                         .mask = sd_numa_mask,
1463                         .sd_flags = cpu_numa_flags,
1464                         .flags = SDTL_OVERLAP,
1465                         .numa_level = j,
1466                         SD_INIT_NAME(NUMA)
1467                 };
1468         }
1469
1470         sched_domain_topology = tl;
1471
1472         sched_domains_numa_levels = level;
1473         sched_max_numa_distance = sched_domains_numa_distance[level - 1];
1474
1475         init_numa_topology_type();
1476 }
1477
1478 void sched_domains_numa_masks_set(unsigned int cpu)
1479 {
1480         int node = cpu_to_node(cpu);
1481         int i, j;
1482
1483         for (i = 0; i < sched_domains_numa_levels; i++) {
1484                 for (j = 0; j < nr_node_ids; j++) {
1485                         if (node_distance(j, node) <= sched_domains_numa_distance[i])
1486                                 cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
1487                 }
1488         }
1489 }
1490
1491 void sched_domains_numa_masks_clear(unsigned int cpu)
1492 {
1493         int i, j;
1494
1495         for (i = 0; i < sched_domains_numa_levels; i++) {
1496                 for (j = 0; j < nr_node_ids; j++)
1497                         cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
1498         }
1499 }
1500
1501 #endif /* CONFIG_NUMA */
1502
1503 static int __sdt_alloc(const struct cpumask *cpu_map)
1504 {
1505         struct sched_domain_topology_level *tl;
1506         int j;
1507
1508         for_each_sd_topology(tl) {
1509                 struct sd_data *sdd = &tl->data;
1510
1511                 sdd->sd = alloc_percpu(struct sched_domain *);
1512                 if (!sdd->sd)
1513                         return -ENOMEM;
1514
1515                 sdd->sds = alloc_percpu(struct sched_domain_shared *);
1516                 if (!sdd->sds)
1517                         return -ENOMEM;
1518
1519                 sdd->sg = alloc_percpu(struct sched_group *);
1520                 if (!sdd->sg)
1521                         return -ENOMEM;
1522
1523                 sdd->sgc = alloc_percpu(struct sched_group_capacity *);
1524                 if (!sdd->sgc)
1525                         return -ENOMEM;
1526
1527                 for_each_cpu(j, cpu_map) {
1528                         struct sched_domain *sd;
1529                         struct sched_domain_shared *sds;
1530                         struct sched_group *sg;
1531                         struct sched_group_capacity *sgc;
1532
1533                         sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
1534                                         GFP_KERNEL, cpu_to_node(j));
1535                         if (!sd)
1536                                 return -ENOMEM;
1537
1538                         *per_cpu_ptr(sdd->sd, j) = sd;
1539
1540                         sds = kzalloc_node(sizeof(struct sched_domain_shared),
1541                                         GFP_KERNEL, cpu_to_node(j));
1542                         if (!sds)
1543                                 return -ENOMEM;
1544
1545                         *per_cpu_ptr(sdd->sds, j) = sds;
1546
1547                         sg = kzalloc_node(sizeof(struct sched_group) + cpumask_size(),
1548                                         GFP_KERNEL, cpu_to_node(j));
1549                         if (!sg)
1550                                 return -ENOMEM;
1551
1552                         sg->next = sg;
1553
1554                         *per_cpu_ptr(sdd->sg, j) = sg;
1555
1556                         sgc = kzalloc_node(sizeof(struct sched_group_capacity) + cpumask_size(),
1557                                         GFP_KERNEL, cpu_to_node(j));
1558                         if (!sgc)
1559                                 return -ENOMEM;
1560
1561 #ifdef CONFIG_SCHED_DEBUG
1562                         sgc->id = j;
1563 #endif
1564
1565                         *per_cpu_ptr(sdd->sgc, j) = sgc;
1566                 }
1567         }
1568
1569         return 0;
1570 }
1571
1572 static void __sdt_free(const struct cpumask *cpu_map)
1573 {
1574         struct sched_domain_topology_level *tl;
1575         int j;
1576
1577         for_each_sd_topology(tl) {
1578                 struct sd_data *sdd = &tl->data;
1579
1580                 for_each_cpu(j, cpu_map) {
1581                         struct sched_domain *sd;
1582
1583                         if (sdd->sd) {
1584                                 sd = *per_cpu_ptr(sdd->sd, j);
1585                                 if (sd && (sd->flags & SD_OVERLAP))
1586                                         free_sched_groups(sd->groups, 0);
1587                                 kfree(*per_cpu_ptr(sdd->sd, j));
1588                         }
1589
1590                         if (sdd->sds)
1591                                 kfree(*per_cpu_ptr(sdd->sds, j));
1592                         if (sdd->sg)
1593                                 kfree(*per_cpu_ptr(sdd->sg, j));
1594                         if (sdd->sgc)
1595                                 kfree(*per_cpu_ptr(sdd->sgc, j));
1596                 }
1597                 free_percpu(sdd->sd);
1598                 sdd->sd = NULL;
1599                 free_percpu(sdd->sds);
1600                 sdd->sds = NULL;
1601                 free_percpu(sdd->sg);
1602                 sdd->sg = NULL;
1603                 free_percpu(sdd->sgc);
1604                 sdd->sgc = NULL;
1605         }
1606 }
1607
1608 static struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl,
1609                 const struct cpumask *cpu_map, struct sched_domain_attr *attr,
1610                 struct sched_domain *child, int cpu)
1611 {
1612         struct sched_domain *sd = sd_init(tl, cpu_map, child, cpu);
1613
1614         if (child) {
1615                 sd->level = child->level + 1;
1616                 sched_domain_level_max = max(sched_domain_level_max, sd->level);
1617                 child->parent = sd;
1618
1619                 if (!cpumask_subset(sched_domain_span(child),
1620                                     sched_domain_span(sd))) {
1621                         pr_err("BUG: arch topology borken\n");
1622 #ifdef CONFIG_SCHED_DEBUG
1623                         pr_err("     the %s domain not a subset of the %s domain\n",
1624                                         child->name, sd->name);
1625 #endif
1626                         /* Fixup, ensure @sd has at least @child CPUs. */
1627                         cpumask_or(sched_domain_span(sd),
1628                                    sched_domain_span(sd),
1629                                    sched_domain_span(child));
1630                 }
1631
1632         }
1633         set_domain_attribute(sd, attr);
1634
1635         return sd;
1636 }
1637
1638 /*
1639  * Build sched domains for a given set of CPUs and attach the sched domains
1640  * to the individual CPUs
1641  */
1642 static int
1643 build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *attr)
1644 {
1645         enum s_alloc alloc_state;
1646         struct sched_domain *sd;
1647         struct s_data d;
1648         struct rq *rq = NULL;
1649         int i, ret = -ENOMEM;
1650
1651         alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
1652         if (alloc_state != sa_rootdomain)
1653                 goto error;
1654
1655         /* Set up domains for CPUs specified by the cpu_map: */
1656         for_each_cpu(i, cpu_map) {
1657                 struct sched_domain_topology_level *tl;
1658
1659                 sd = NULL;
1660                 for_each_sd_topology(tl) {
1661                         sd = build_sched_domain(tl, cpu_map, attr, sd, i);
1662                         if (tl == sched_domain_topology)
1663                                 *per_cpu_ptr(d.sd, i) = sd;
1664                         if (tl->flags & SDTL_OVERLAP)
1665                                 sd->flags |= SD_OVERLAP;
1666                         if (cpumask_equal(cpu_map, sched_domain_span(sd)))
1667                                 break;
1668                 }
1669         }
1670
1671         /* Build the groups for the domains */
1672         for_each_cpu(i, cpu_map) {
1673                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
1674                         sd->span_weight = cpumask_weight(sched_domain_span(sd));
1675                         if (sd->flags & SD_OVERLAP) {
1676                                 if (build_overlap_sched_groups(sd, i))
1677                                         goto error;
1678                         } else {
1679                                 if (build_sched_groups(sd, i))
1680                                         goto error;
1681                         }
1682                 }
1683         }
1684
1685         /* Calculate CPU capacity for physical packages and nodes */
1686         for (i = nr_cpumask_bits-1; i >= 0; i--) {
1687                 if (!cpumask_test_cpu(i, cpu_map))
1688                         continue;
1689
1690                 for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
1691                         claim_allocations(i, sd);
1692                         init_sched_groups_capacity(i, sd);
1693                 }
1694         }
1695
1696         /* Attach the domains */
1697         rcu_read_lock();
1698         for_each_cpu(i, cpu_map) {
1699                 rq = cpu_rq(i);
1700                 sd = *per_cpu_ptr(d.sd, i);
1701
1702                 /* Use READ_ONCE()/WRITE_ONCE() to avoid load/store tearing: */
1703                 if (rq->cpu_capacity_orig > READ_ONCE(d.rd->max_cpu_capacity))
1704                         WRITE_ONCE(d.rd->max_cpu_capacity, rq->cpu_capacity_orig);
1705
1706                 cpu_attach_domain(sd, d.rd, i);
1707         }
1708         rcu_read_unlock();
1709
1710         if (rq && sched_debug_enabled) {
1711                 pr_info("root domain span: %*pbl (max cpu_capacity = %lu)\n",
1712                         cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity);
1713         }
1714
1715         ret = 0;
1716 error:
1717         __free_domain_allocs(&d, alloc_state, cpu_map);
1718
1719         return ret;
1720 }
1721
1722 /* Current sched domains: */
1723 static cpumask_var_t                    *doms_cur;
1724
1725 /* Number of sched domains in 'doms_cur': */
1726 static int                              ndoms_cur;
1727
1728 /* Attribues of custom domains in 'doms_cur' */
1729 static struct sched_domain_attr         *dattr_cur;
1730
1731 /*
1732  * Special case: If a kmalloc() of a doms_cur partition (array of
1733  * cpumask) fails, then fallback to a single sched domain,
1734  * as determined by the single cpumask fallback_doms.
1735  */
1736 static cpumask_var_t                    fallback_doms;
1737
1738 /*
1739  * arch_update_cpu_topology lets virtualized architectures update the
1740  * CPU core maps. It is supposed to return 1 if the topology changed
1741  * or 0 if it stayed the same.
1742  */
1743 int __weak arch_update_cpu_topology(void)
1744 {
1745         return 0;
1746 }
1747
1748 cpumask_var_t *alloc_sched_domains(unsigned int ndoms)
1749 {
1750         int i;
1751         cpumask_var_t *doms;
1752
1753         doms = kmalloc(sizeof(*doms) * ndoms, GFP_KERNEL);
1754         if (!doms)
1755                 return NULL;
1756         for (i = 0; i < ndoms; i++) {
1757                 if (!alloc_cpumask_var(&doms[i], GFP_KERNEL)) {
1758                         free_sched_domains(doms, i);
1759                         return NULL;
1760                 }
1761         }
1762         return doms;
1763 }
1764
1765 void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms)
1766 {
1767         unsigned int i;
1768         for (i = 0; i < ndoms; i++)
1769                 free_cpumask_var(doms[i]);
1770         kfree(doms);
1771 }
1772
1773 /*
1774  * Set up scheduler domains and groups. Callers must hold the hotplug lock.
1775  * For now this just excludes isolated CPUs, but could be used to
1776  * exclude other special cases in the future.
1777  */
1778 int sched_init_domains(const struct cpumask *cpu_map)
1779 {
1780         int err;
1781
1782         zalloc_cpumask_var(&sched_domains_tmpmask, GFP_KERNEL);
1783         zalloc_cpumask_var(&sched_domains_tmpmask2, GFP_KERNEL);
1784         zalloc_cpumask_var(&fallback_doms, GFP_KERNEL);
1785
1786         arch_update_cpu_topology();
1787         ndoms_cur = 1;
1788         doms_cur = alloc_sched_domains(ndoms_cur);
1789         if (!doms_cur)
1790                 doms_cur = &fallback_doms;
1791         cpumask_and(doms_cur[0], cpu_map, housekeeping_cpumask(HK_FLAG_DOMAIN));
1792         err = build_sched_domains(doms_cur[0], NULL);
1793         register_sched_domain_sysctl();
1794
1795         return err;
1796 }
1797
1798 /*
1799  * Detach sched domains from a group of CPUs specified in cpu_map
1800  * These CPUs will now be attached to the NULL domain
1801  */
1802 static void detach_destroy_domains(const struct cpumask *cpu_map)
1803 {
1804         int i;
1805
1806         rcu_read_lock();
1807         for_each_cpu(i, cpu_map)
1808                 cpu_attach_domain(NULL, &def_root_domain, i);
1809         rcu_read_unlock();
1810 }
1811
1812 /* handle null as "default" */
1813 static int dattrs_equal(struct sched_domain_attr *cur, int idx_cur,
1814                         struct sched_domain_attr *new, int idx_new)
1815 {
1816         struct sched_domain_attr tmp;
1817
1818         /* Fast path: */
1819         if (!new && !cur)
1820                 return 1;
1821
1822         tmp = SD_ATTR_INIT;
1823
1824         return !memcmp(cur ? (cur + idx_cur) : &tmp,
1825                         new ? (new + idx_new) : &tmp,
1826                         sizeof(struct sched_domain_attr));
1827 }
1828
1829 /*
1830  * Partition sched domains as specified by the 'ndoms_new'
1831  * cpumasks in the array doms_new[] of cpumasks. This compares
1832  * doms_new[] to the current sched domain partitioning, doms_cur[].
1833  * It destroys each deleted domain and builds each new domain.
1834  *
1835  * 'doms_new' is an array of cpumask_var_t's of length 'ndoms_new'.
1836  * The masks don't intersect (don't overlap.) We should setup one
1837  * sched domain for each mask. CPUs not in any of the cpumasks will
1838  * not be load balanced. If the same cpumask appears both in the
1839  * current 'doms_cur' domains and in the new 'doms_new', we can leave
1840  * it as it is.
1841  *
1842  * The passed in 'doms_new' should be allocated using
1843  * alloc_sched_domains.  This routine takes ownership of it and will
1844  * free_sched_domains it when done with it. If the caller failed the
1845  * alloc call, then it can pass in doms_new == NULL && ndoms_new == 1,
1846  * and partition_sched_domains() will fallback to the single partition
1847  * 'fallback_doms', it also forces the domains to be rebuilt.
1848  *
1849  * If doms_new == NULL it will be replaced with cpu_online_mask.
1850  * ndoms_new == 0 is a special case for destroying existing domains,
1851  * and it will not create the default domain.
1852  *
1853  * Call with hotplug lock held
1854  */
1855 void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
1856                              struct sched_domain_attr *dattr_new)
1857 {
1858         int i, j, n;
1859         int new_topology;
1860
1861         mutex_lock(&sched_domains_mutex);
1862
1863         /* Always unregister in case we don't destroy any domains: */
1864         unregister_sched_domain_sysctl();
1865
1866         /* Let the architecture update CPU core mappings: */
1867         new_topology = arch_update_cpu_topology();
1868
1869         if (!doms_new) {
1870                 WARN_ON_ONCE(dattr_new);
1871                 n = 0;
1872                 doms_new = alloc_sched_domains(1);
1873                 if (doms_new) {
1874                         n = 1;
1875                         cpumask_and(doms_new[0], cpu_active_mask,
1876                                     housekeeping_cpumask(HK_FLAG_DOMAIN));
1877                 }
1878         } else {
1879                 n = ndoms_new;
1880         }
1881
1882         /* Destroy deleted domains: */
1883         for (i = 0; i < ndoms_cur; i++) {
1884                 for (j = 0; j < n && !new_topology; j++) {
1885                         if (cpumask_equal(doms_cur[i], doms_new[j])
1886                             && dattrs_equal(dattr_cur, i, dattr_new, j))
1887                                 goto match1;
1888                 }
1889                 /* No match - a current sched domain not in new doms_new[] */
1890                 detach_destroy_domains(doms_cur[i]);
1891 match1:
1892                 ;
1893         }
1894
1895         n = ndoms_cur;
1896         if (!doms_new) {
1897                 n = 0;
1898                 doms_new = &fallback_doms;
1899                 cpumask_and(doms_new[0], cpu_active_mask,
1900                             housekeeping_cpumask(HK_FLAG_DOMAIN));
1901         }
1902
1903         /* Build new domains: */
1904         for (i = 0; i < ndoms_new; i++) {
1905                 for (j = 0; j < n && !new_topology; j++) {
1906                         if (cpumask_equal(doms_new[i], doms_cur[j])
1907                             && dattrs_equal(dattr_new, i, dattr_cur, j))
1908                                 goto match2;
1909                 }
1910                 /* No match - add a new doms_new */
1911                 build_sched_domains(doms_new[i], dattr_new ? dattr_new + i : NULL);
1912 match2:
1913                 ;
1914         }
1915
1916         /* Remember the new sched domains: */
1917         if (doms_cur != &fallback_doms)
1918                 free_sched_domains(doms_cur, ndoms_cur);
1919
1920         kfree(dattr_cur);
1921         doms_cur = doms_new;
1922         dattr_cur = dattr_new;
1923         ndoms_cur = ndoms_new;
1924
1925         register_sched_domain_sysctl();
1926
1927         mutex_unlock(&sched_domains_mutex);
1928 }