mm, oom: remove oom_lock from oom_reaper
[linux/fpc-iii.git] / kernel / cgroup / cgroup-v1.c
blob8b4f0768efd62244d3939b985059963371e04d63
1 #include "cgroup-internal.h"
3 #include <linux/ctype.h>
4 #include <linux/kmod.h>
5 #include <linux/sort.h>
6 #include <linux/delay.h>
7 #include <linux/mm.h>
8 #include <linux/sched/signal.h>
9 #include <linux/sched/task.h>
10 #include <linux/magic.h>
11 #include <linux/slab.h>
12 #include <linux/vmalloc.h>
13 #include <linux/delayacct.h>
14 #include <linux/pid_namespace.h>
15 #include <linux/cgroupstats.h>
17 #include <trace/events/cgroup.h>
20 * pidlists linger the following amount before being destroyed. The goal
21 * is avoiding frequent destruction in the middle of consecutive read calls
22 * Expiring in the middle is a performance problem not a correctness one.
23 * 1 sec should be enough.
25 #define CGROUP_PIDLIST_DESTROY_DELAY HZ
27 /* Controllers blocked by the commandline in v1 */
28 static u16 cgroup_no_v1_mask;
31 * pidlist destructions need to be flushed on cgroup destruction. Use a
32 * separate workqueue as flush domain.
34 static struct workqueue_struct *cgroup_pidlist_destroy_wq;
37 * Protects cgroup_subsys->release_agent_path. Modifying it also requires
38 * cgroup_mutex. Reading requires either cgroup_mutex or this spinlock.
40 static DEFINE_SPINLOCK(release_agent_path_lock);
42 bool cgroup1_ssid_disabled(int ssid)
44 return cgroup_no_v1_mask & (1 << ssid);
47 /**
48 * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
49 * @from: attach to all cgroups of a given task
50 * @tsk: the task to be attached
52 int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
54 struct cgroup_root *root;
55 int retval = 0;
57 mutex_lock(&cgroup_mutex);
58 percpu_down_write(&cgroup_threadgroup_rwsem);
59 for_each_root(root) {
60 struct cgroup *from_cgrp;
62 if (root == &cgrp_dfl_root)
63 continue;
65 spin_lock_irq(&css_set_lock);
66 from_cgrp = task_cgroup_from_root(from, root);
67 spin_unlock_irq(&css_set_lock);
69 retval = cgroup_attach_task(from_cgrp, tsk, false);
70 if (retval)
71 break;
73 percpu_up_write(&cgroup_threadgroup_rwsem);
74 mutex_unlock(&cgroup_mutex);
76 return retval;
78 EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
80 /**
81 * cgroup_trasnsfer_tasks - move tasks from one cgroup to another
82 * @to: cgroup to which the tasks will be moved
83 * @from: cgroup in which the tasks currently reside
85 * Locking rules between cgroup_post_fork() and the migration path
86 * guarantee that, if a task is forking while being migrated, the new child
87 * is guaranteed to be either visible in the source cgroup after the
88 * parent's migration is complete or put into the target cgroup. No task
89 * can slip out of migration through forking.
91 int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
93 DEFINE_CGROUP_MGCTX(mgctx);
94 struct cgrp_cset_link *link;
95 struct css_task_iter it;
96 struct task_struct *task;
97 int ret;
99 if (cgroup_on_dfl(to))
100 return -EINVAL;
102 ret = cgroup_migrate_vet_dst(to);
103 if (ret)
104 return ret;
106 mutex_lock(&cgroup_mutex);
108 percpu_down_write(&cgroup_threadgroup_rwsem);
110 /* all tasks in @from are being moved, all csets are source */
111 spin_lock_irq(&css_set_lock);
112 list_for_each_entry(link, &from->cset_links, cset_link)
113 cgroup_migrate_add_src(link->cset, to, &mgctx);
114 spin_unlock_irq(&css_set_lock);
116 ret = cgroup_migrate_prepare_dst(&mgctx);
117 if (ret)
118 goto out_err;
121 * Migrate tasks one-by-one until @from is empty. This fails iff
122 * ->can_attach() fails.
124 do {
125 css_task_iter_start(&from->self, 0, &it);
127 do {
128 task = css_task_iter_next(&it);
129 } while (task && (task->flags & PF_EXITING));
131 if (task)
132 get_task_struct(task);
133 css_task_iter_end(&it);
135 if (task) {
136 ret = cgroup_migrate(task, false, &mgctx);
137 if (!ret)
138 trace_cgroup_transfer_tasks(to, task, false);
139 put_task_struct(task);
141 } while (task && !ret);
142 out_err:
143 cgroup_migrate_finish(&mgctx);
144 percpu_up_write(&cgroup_threadgroup_rwsem);
145 mutex_unlock(&cgroup_mutex);
146 return ret;
150 * Stuff for reading the 'tasks'/'procs' files.
152 * Reading this file can return large amounts of data if a cgroup has
153 * *lots* of attached tasks. So it may need several calls to read(),
154 * but we cannot guarantee that the information we produce is correct
155 * unless we produce it entirely atomically.
159 /* which pidlist file are we talking about? */
160 enum cgroup_filetype {
161 CGROUP_FILE_PROCS,
162 CGROUP_FILE_TASKS,
166 * A pidlist is a list of pids that virtually represents the contents of one
167 * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
168 * a pair (one each for procs, tasks) for each pid namespace that's relevant
169 * to the cgroup.
171 struct cgroup_pidlist {
173 * used to find which pidlist is wanted. doesn't change as long as
174 * this particular list stays in the list.
176 struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
177 /* array of xids */
178 pid_t *list;
179 /* how many elements the above list has */
180 int length;
181 /* each of these stored in a list by its cgroup */
182 struct list_head links;
183 /* pointer to the cgroup we belong to, for list removal purposes */
184 struct cgroup *owner;
185 /* for delayed destruction */
186 struct delayed_work destroy_dwork;
190 * The following two functions "fix" the issue where there are more pids
191 * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
192 * TODO: replace with a kernel-wide solution to this problem
194 #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
195 static void *pidlist_allocate(int count)
197 if (PIDLIST_TOO_LARGE(count))
198 return vmalloc(array_size(count, sizeof(pid_t)));
199 else
200 return kmalloc_array(count, sizeof(pid_t), GFP_KERNEL);
203 static void pidlist_free(void *p)
205 kvfree(p);
209 * Used to destroy all pidlists lingering waiting for destroy timer. None
210 * should be left afterwards.
212 void cgroup1_pidlist_destroy_all(struct cgroup *cgrp)
214 struct cgroup_pidlist *l, *tmp_l;
216 mutex_lock(&cgrp->pidlist_mutex);
217 list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links)
218 mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0);
219 mutex_unlock(&cgrp->pidlist_mutex);
221 flush_workqueue(cgroup_pidlist_destroy_wq);
222 BUG_ON(!list_empty(&cgrp->pidlists));
225 static void cgroup_pidlist_destroy_work_fn(struct work_struct *work)
227 struct delayed_work *dwork = to_delayed_work(work);
228 struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist,
229 destroy_dwork);
230 struct cgroup_pidlist *tofree = NULL;
232 mutex_lock(&l->owner->pidlist_mutex);
235 * Destroy iff we didn't get queued again. The state won't change
236 * as destroy_dwork can only be queued while locked.
238 if (!delayed_work_pending(dwork)) {
239 list_del(&l->links);
240 pidlist_free(l->list);
241 put_pid_ns(l->key.ns);
242 tofree = l;
245 mutex_unlock(&l->owner->pidlist_mutex);
246 kfree(tofree);
250 * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
251 * Returns the number of unique elements.
253 static int pidlist_uniq(pid_t *list, int length)
255 int src, dest = 1;
258 * we presume the 0th element is unique, so i starts at 1. trivial
259 * edge cases first; no work needs to be done for either
261 if (length == 0 || length == 1)
262 return length;
263 /* src and dest walk down the list; dest counts unique elements */
264 for (src = 1; src < length; src++) {
265 /* find next unique element */
266 while (list[src] == list[src-1]) {
267 src++;
268 if (src == length)
269 goto after;
271 /* dest always points to where the next unique element goes */
272 list[dest] = list[src];
273 dest++;
275 after:
276 return dest;
280 * The two pid files - task and cgroup.procs - guaranteed that the result
281 * is sorted, which forced this whole pidlist fiasco. As pid order is
282 * different per namespace, each namespace needs differently sorted list,
283 * making it impossible to use, for example, single rbtree of member tasks
284 * sorted by task pointer. As pidlists can be fairly large, allocating one
285 * per open file is dangerous, so cgroup had to implement shared pool of
286 * pidlists keyed by cgroup and namespace.
288 static int cmppid(const void *a, const void *b)
290 return *(pid_t *)a - *(pid_t *)b;
293 static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
294 enum cgroup_filetype type)
296 struct cgroup_pidlist *l;
297 /* don't need task_nsproxy() if we're looking at ourself */
298 struct pid_namespace *ns = task_active_pid_ns(current);
300 lockdep_assert_held(&cgrp->pidlist_mutex);
302 list_for_each_entry(l, &cgrp->pidlists, links)
303 if (l->key.type == type && l->key.ns == ns)
304 return l;
305 return NULL;
309 * find the appropriate pidlist for our purpose (given procs vs tasks)
310 * returns with the lock on that pidlist already held, and takes care
311 * of the use count, or returns NULL with no locks held if we're out of
312 * memory.
314 static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp,
315 enum cgroup_filetype type)
317 struct cgroup_pidlist *l;
319 lockdep_assert_held(&cgrp->pidlist_mutex);
321 l = cgroup_pidlist_find(cgrp, type);
322 if (l)
323 return l;
325 /* entry not found; create a new one */
326 l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
327 if (!l)
328 return l;
330 INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn);
331 l->key.type = type;
332 /* don't need task_nsproxy() if we're looking at ourself */
333 l->key.ns = get_pid_ns(task_active_pid_ns(current));
334 l->owner = cgrp;
335 list_add(&l->links, &cgrp->pidlists);
336 return l;
340 * cgroup_task_count - count the number of tasks in a cgroup.
341 * @cgrp: the cgroup in question
343 int cgroup_task_count(const struct cgroup *cgrp)
345 int count = 0;
346 struct cgrp_cset_link *link;
348 spin_lock_irq(&css_set_lock);
349 list_for_each_entry(link, &cgrp->cset_links, cset_link)
350 count += link->cset->nr_tasks;
351 spin_unlock_irq(&css_set_lock);
352 return count;
356 * Load a cgroup's pidarray with either procs' tgids or tasks' pids
358 static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
359 struct cgroup_pidlist **lp)
361 pid_t *array;
362 int length;
363 int pid, n = 0; /* used for populating the array */
364 struct css_task_iter it;
365 struct task_struct *tsk;
366 struct cgroup_pidlist *l;
368 lockdep_assert_held(&cgrp->pidlist_mutex);
371 * If cgroup gets more users after we read count, we won't have
372 * enough space - tough. This race is indistinguishable to the
373 * caller from the case that the additional cgroup users didn't
374 * show up until sometime later on.
376 length = cgroup_task_count(cgrp);
377 array = pidlist_allocate(length);
378 if (!array)
379 return -ENOMEM;
380 /* now, populate the array */
381 css_task_iter_start(&cgrp->self, 0, &it);
382 while ((tsk = css_task_iter_next(&it))) {
383 if (unlikely(n == length))
384 break;
385 /* get tgid or pid for procs or tasks file respectively */
386 if (type == CGROUP_FILE_PROCS)
387 pid = task_tgid_vnr(tsk);
388 else
389 pid = task_pid_vnr(tsk);
390 if (pid > 0) /* make sure to only use valid results */
391 array[n++] = pid;
393 css_task_iter_end(&it);
394 length = n;
395 /* now sort & (if procs) strip out duplicates */
396 sort(array, length, sizeof(pid_t), cmppid, NULL);
397 if (type == CGROUP_FILE_PROCS)
398 length = pidlist_uniq(array, length);
400 l = cgroup_pidlist_find_create(cgrp, type);
401 if (!l) {
402 pidlist_free(array);
403 return -ENOMEM;
406 /* store array, freeing old if necessary */
407 pidlist_free(l->list);
408 l->list = array;
409 l->length = length;
410 *lp = l;
411 return 0;
415 * seq_file methods for the tasks/procs files. The seq_file position is the
416 * next pid to display; the seq_file iterator is a pointer to the pid
417 * in the cgroup->l->list array.
420 static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
423 * Initially we receive a position value that corresponds to
424 * one more than the last pid shown (or 0 on the first call or
425 * after a seek to the start). Use a binary-search to find the
426 * next pid to display, if any
428 struct kernfs_open_file *of = s->private;
429 struct cgroup *cgrp = seq_css(s)->cgroup;
430 struct cgroup_pidlist *l;
431 enum cgroup_filetype type = seq_cft(s)->private;
432 int index = 0, pid = *pos;
433 int *iter, ret;
435 mutex_lock(&cgrp->pidlist_mutex);
438 * !NULL @of->priv indicates that this isn't the first start()
439 * after open. If the matching pidlist is around, we can use that.
440 * Look for it. Note that @of->priv can't be used directly. It
441 * could already have been destroyed.
443 if (of->priv)
444 of->priv = cgroup_pidlist_find(cgrp, type);
447 * Either this is the first start() after open or the matching
448 * pidlist has been destroyed inbetween. Create a new one.
450 if (!of->priv) {
451 ret = pidlist_array_load(cgrp, type,
452 (struct cgroup_pidlist **)&of->priv);
453 if (ret)
454 return ERR_PTR(ret);
456 l = of->priv;
458 if (pid) {
459 int end = l->length;
461 while (index < end) {
462 int mid = (index + end) / 2;
463 if (l->list[mid] == pid) {
464 index = mid;
465 break;
466 } else if (l->list[mid] <= pid)
467 index = mid + 1;
468 else
469 end = mid;
472 /* If we're off the end of the array, we're done */
473 if (index >= l->length)
474 return NULL;
475 /* Update the abstract position to be the actual pid that we found */
476 iter = l->list + index;
477 *pos = *iter;
478 return iter;
481 static void cgroup_pidlist_stop(struct seq_file *s, void *v)
483 struct kernfs_open_file *of = s->private;
484 struct cgroup_pidlist *l = of->priv;
486 if (l)
487 mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork,
488 CGROUP_PIDLIST_DESTROY_DELAY);
489 mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex);
492 static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
494 struct kernfs_open_file *of = s->private;
495 struct cgroup_pidlist *l = of->priv;
496 pid_t *p = v;
497 pid_t *end = l->list + l->length;
499 * Advance to the next pid in the array. If this goes off the
500 * end, we're done
502 p++;
503 if (p >= end) {
504 return NULL;
505 } else {
506 *pos = *p;
507 return p;
511 static int cgroup_pidlist_show(struct seq_file *s, void *v)
513 seq_printf(s, "%d\n", *(int *)v);
515 return 0;
518 static ssize_t __cgroup1_procs_write(struct kernfs_open_file *of,
519 char *buf, size_t nbytes, loff_t off,
520 bool threadgroup)
522 struct cgroup *cgrp;
523 struct task_struct *task;
524 const struct cred *cred, *tcred;
525 ssize_t ret;
527 cgrp = cgroup_kn_lock_live(of->kn, false);
528 if (!cgrp)
529 return -ENODEV;
531 task = cgroup_procs_write_start(buf, threadgroup);
532 ret = PTR_ERR_OR_ZERO(task);
533 if (ret)
534 goto out_unlock;
537 * Even if we're attaching all tasks in the thread group, we only
538 * need to check permissions on one of them.
540 cred = current_cred();
541 tcred = get_task_cred(task);
542 if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
543 !uid_eq(cred->euid, tcred->uid) &&
544 !uid_eq(cred->euid, tcred->suid))
545 ret = -EACCES;
546 put_cred(tcred);
547 if (ret)
548 goto out_finish;
550 ret = cgroup_attach_task(cgrp, task, threadgroup);
552 out_finish:
553 cgroup_procs_write_finish(task);
554 out_unlock:
555 cgroup_kn_unlock(of->kn);
557 return ret ?: nbytes;
560 static ssize_t cgroup1_procs_write(struct kernfs_open_file *of,
561 char *buf, size_t nbytes, loff_t off)
563 return __cgroup1_procs_write(of, buf, nbytes, off, true);
566 static ssize_t cgroup1_tasks_write(struct kernfs_open_file *of,
567 char *buf, size_t nbytes, loff_t off)
569 return __cgroup1_procs_write(of, buf, nbytes, off, false);
572 static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
573 char *buf, size_t nbytes, loff_t off)
575 struct cgroup *cgrp;
577 BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
579 cgrp = cgroup_kn_lock_live(of->kn, false);
580 if (!cgrp)
581 return -ENODEV;
582 spin_lock(&release_agent_path_lock);
583 strlcpy(cgrp->root->release_agent_path, strstrip(buf),
584 sizeof(cgrp->root->release_agent_path));
585 spin_unlock(&release_agent_path_lock);
586 cgroup_kn_unlock(of->kn);
587 return nbytes;
590 static int cgroup_release_agent_show(struct seq_file *seq, void *v)
592 struct cgroup *cgrp = seq_css(seq)->cgroup;
594 spin_lock(&release_agent_path_lock);
595 seq_puts(seq, cgrp->root->release_agent_path);
596 spin_unlock(&release_agent_path_lock);
597 seq_putc(seq, '\n');
598 return 0;
601 static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
603 seq_puts(seq, "0\n");
604 return 0;
607 static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,
608 struct cftype *cft)
610 return notify_on_release(css->cgroup);
613 static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css,
614 struct cftype *cft, u64 val)
616 if (val)
617 set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
618 else
619 clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
620 return 0;
623 static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css,
624 struct cftype *cft)
626 return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
629 static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
630 struct cftype *cft, u64 val)
632 if (val)
633 set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
634 else
635 clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
636 return 0;
639 /* cgroup core interface files for the legacy hierarchies */
640 struct cftype cgroup1_base_files[] = {
642 .name = "cgroup.procs",
643 .seq_start = cgroup_pidlist_start,
644 .seq_next = cgroup_pidlist_next,
645 .seq_stop = cgroup_pidlist_stop,
646 .seq_show = cgroup_pidlist_show,
647 .private = CGROUP_FILE_PROCS,
648 .write = cgroup1_procs_write,
651 .name = "cgroup.clone_children",
652 .read_u64 = cgroup_clone_children_read,
653 .write_u64 = cgroup_clone_children_write,
656 .name = "cgroup.sane_behavior",
657 .flags = CFTYPE_ONLY_ON_ROOT,
658 .seq_show = cgroup_sane_behavior_show,
661 .name = "tasks",
662 .seq_start = cgroup_pidlist_start,
663 .seq_next = cgroup_pidlist_next,
664 .seq_stop = cgroup_pidlist_stop,
665 .seq_show = cgroup_pidlist_show,
666 .private = CGROUP_FILE_TASKS,
667 .write = cgroup1_tasks_write,
670 .name = "notify_on_release",
671 .read_u64 = cgroup_read_notify_on_release,
672 .write_u64 = cgroup_write_notify_on_release,
675 .name = "release_agent",
676 .flags = CFTYPE_ONLY_ON_ROOT,
677 .seq_show = cgroup_release_agent_show,
678 .write = cgroup_release_agent_write,
679 .max_write_len = PATH_MAX - 1,
681 { } /* terminate */
684 /* Display information about each subsystem and each hierarchy */
685 int proc_cgroupstats_show(struct seq_file *m, void *v)
687 struct cgroup_subsys *ss;
688 int i;
690 seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
692 * ideally we don't want subsystems moving around while we do this.
693 * cgroup_mutex is also necessary to guarantee an atomic snapshot of
694 * subsys/hierarchy state.
696 mutex_lock(&cgroup_mutex);
698 for_each_subsys(ss, i)
699 seq_printf(m, "%s\t%d\t%d\t%d\n",
700 ss->legacy_name, ss->root->hierarchy_id,
701 atomic_read(&ss->root->nr_cgrps),
702 cgroup_ssid_enabled(i));
704 mutex_unlock(&cgroup_mutex);
705 return 0;
709 * cgroupstats_build - build and fill cgroupstats
710 * @stats: cgroupstats to fill information into
711 * @dentry: A dentry entry belonging to the cgroup for which stats have
712 * been requested.
714 * Build and fill cgroupstats so that taskstats can export it to user
715 * space.
717 int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
719 struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
720 struct cgroup *cgrp;
721 struct css_task_iter it;
722 struct task_struct *tsk;
724 /* it should be kernfs_node belonging to cgroupfs and is a directory */
725 if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
726 kernfs_type(kn) != KERNFS_DIR)
727 return -EINVAL;
729 mutex_lock(&cgroup_mutex);
732 * We aren't being called from kernfs and there's no guarantee on
733 * @kn->priv's validity. For this and css_tryget_online_from_dir(),
734 * @kn->priv is RCU safe. Let's do the RCU dancing.
736 rcu_read_lock();
737 cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv);
738 if (!cgrp || cgroup_is_dead(cgrp)) {
739 rcu_read_unlock();
740 mutex_unlock(&cgroup_mutex);
741 return -ENOENT;
743 rcu_read_unlock();
745 css_task_iter_start(&cgrp->self, 0, &it);
746 while ((tsk = css_task_iter_next(&it))) {
747 switch (tsk->state) {
748 case TASK_RUNNING:
749 stats->nr_running++;
750 break;
751 case TASK_INTERRUPTIBLE:
752 stats->nr_sleeping++;
753 break;
754 case TASK_UNINTERRUPTIBLE:
755 stats->nr_uninterruptible++;
756 break;
757 case TASK_STOPPED:
758 stats->nr_stopped++;
759 break;
760 default:
761 if (delayacct_is_task_waiting_on_io(tsk))
762 stats->nr_io_wait++;
763 break;
766 css_task_iter_end(&it);
768 mutex_unlock(&cgroup_mutex);
769 return 0;
772 void cgroup1_check_for_release(struct cgroup *cgrp)
774 if (notify_on_release(cgrp) && !cgroup_is_populated(cgrp) &&
775 !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp))
776 schedule_work(&cgrp->release_agent_work);
780 * Notify userspace when a cgroup is released, by running the
781 * configured release agent with the name of the cgroup (path
782 * relative to the root of cgroup file system) as the argument.
784 * Most likely, this user command will try to rmdir this cgroup.
786 * This races with the possibility that some other task will be
787 * attached to this cgroup before it is removed, or that some other
788 * user task will 'mkdir' a child cgroup of this cgroup. That's ok.
789 * The presumed 'rmdir' will fail quietly if this cgroup is no longer
790 * unused, and this cgroup will be reprieved from its death sentence,
791 * to continue to serve a useful existence. Next time it's released,
792 * we will get notified again, if it still has 'notify_on_release' set.
794 * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
795 * means only wait until the task is successfully execve()'d. The
796 * separate release agent task is forked by call_usermodehelper(),
797 * then control in this thread returns here, without waiting for the
798 * release agent task. We don't bother to wait because the caller of
799 * this routine has no use for the exit status of the release agent
800 * task, so no sense holding our caller up for that.
802 void cgroup1_release_agent(struct work_struct *work)
804 struct cgroup *cgrp =
805 container_of(work, struct cgroup, release_agent_work);
806 char *pathbuf = NULL, *agentbuf = NULL;
807 char *argv[3], *envp[3];
808 int ret;
810 mutex_lock(&cgroup_mutex);
812 pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
813 agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL);
814 if (!pathbuf || !agentbuf)
815 goto out;
817 spin_lock_irq(&css_set_lock);
818 ret = cgroup_path_ns_locked(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns);
819 spin_unlock_irq(&css_set_lock);
820 if (ret < 0 || ret >= PATH_MAX)
821 goto out;
823 argv[0] = agentbuf;
824 argv[1] = pathbuf;
825 argv[2] = NULL;
827 /* minimal command environment */
828 envp[0] = "HOME=/";
829 envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
830 envp[2] = NULL;
832 mutex_unlock(&cgroup_mutex);
833 call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
834 goto out_free;
835 out:
836 mutex_unlock(&cgroup_mutex);
837 out_free:
838 kfree(agentbuf);
839 kfree(pathbuf);
843 * cgroup_rename - Only allow simple rename of directories in place.
845 static int cgroup1_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
846 const char *new_name_str)
848 struct cgroup *cgrp = kn->priv;
849 int ret;
851 if (kernfs_type(kn) != KERNFS_DIR)
852 return -ENOTDIR;
853 if (kn->parent != new_parent)
854 return -EIO;
857 * We're gonna grab cgroup_mutex which nests outside kernfs
858 * active_ref. kernfs_rename() doesn't require active_ref
859 * protection. Break them before grabbing cgroup_mutex.
861 kernfs_break_active_protection(new_parent);
862 kernfs_break_active_protection(kn);
864 mutex_lock(&cgroup_mutex);
866 ret = kernfs_rename(kn, new_parent, new_name_str);
867 if (!ret)
868 trace_cgroup_rename(cgrp);
870 mutex_unlock(&cgroup_mutex);
872 kernfs_unbreak_active_protection(kn);
873 kernfs_unbreak_active_protection(new_parent);
874 return ret;
877 static int cgroup1_show_options(struct seq_file *seq, struct kernfs_root *kf_root)
879 struct cgroup_root *root = cgroup_root_from_kf(kf_root);
880 struct cgroup_subsys *ss;
881 int ssid;
883 for_each_subsys(ss, ssid)
884 if (root->subsys_mask & (1 << ssid))
885 seq_show_option(seq, ss->legacy_name, NULL);
886 if (root->flags & CGRP_ROOT_NOPREFIX)
887 seq_puts(seq, ",noprefix");
888 if (root->flags & CGRP_ROOT_XATTR)
889 seq_puts(seq, ",xattr");
890 if (root->flags & CGRP_ROOT_CPUSET_V2_MODE)
891 seq_puts(seq, ",cpuset_v2_mode");
893 spin_lock(&release_agent_path_lock);
894 if (strlen(root->release_agent_path))
895 seq_show_option(seq, "release_agent",
896 root->release_agent_path);
897 spin_unlock(&release_agent_path_lock);
899 if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags))
900 seq_puts(seq, ",clone_children");
901 if (strlen(root->name))
902 seq_show_option(seq, "name", root->name);
903 return 0;
906 static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
908 char *token, *o = data;
909 bool all_ss = false, one_ss = false;
910 u16 mask = U16_MAX;
911 struct cgroup_subsys *ss;
912 int nr_opts = 0;
913 int i;
915 #ifdef CONFIG_CPUSETS
916 mask = ~((u16)1 << cpuset_cgrp_id);
917 #endif
919 memset(opts, 0, sizeof(*opts));
921 while ((token = strsep(&o, ",")) != NULL) {
922 nr_opts++;
924 if (!*token)
925 return -EINVAL;
926 if (!strcmp(token, "none")) {
927 /* Explicitly have no subsystems */
928 opts->none = true;
929 continue;
931 if (!strcmp(token, "all")) {
932 /* Mutually exclusive option 'all' + subsystem name */
933 if (one_ss)
934 return -EINVAL;
935 all_ss = true;
936 continue;
938 if (!strcmp(token, "noprefix")) {
939 opts->flags |= CGRP_ROOT_NOPREFIX;
940 continue;
942 if (!strcmp(token, "clone_children")) {
943 opts->cpuset_clone_children = true;
944 continue;
946 if (!strcmp(token, "cpuset_v2_mode")) {
947 opts->flags |= CGRP_ROOT_CPUSET_V2_MODE;
948 continue;
950 if (!strcmp(token, "xattr")) {
951 opts->flags |= CGRP_ROOT_XATTR;
952 continue;
954 if (!strncmp(token, "release_agent=", 14)) {
955 /* Specifying two release agents is forbidden */
956 if (opts->release_agent)
957 return -EINVAL;
958 opts->release_agent =
959 kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL);
960 if (!opts->release_agent)
961 return -ENOMEM;
962 continue;
964 if (!strncmp(token, "name=", 5)) {
965 const char *name = token + 5;
966 /* Can't specify an empty name */
967 if (!strlen(name))
968 return -EINVAL;
969 /* Must match [\w.-]+ */
970 for (i = 0; i < strlen(name); i++) {
971 char c = name[i];
972 if (isalnum(c))
973 continue;
974 if ((c == '.') || (c == '-') || (c == '_'))
975 continue;
976 return -EINVAL;
978 /* Specifying two names is forbidden */
979 if (opts->name)
980 return -EINVAL;
981 opts->name = kstrndup(name,
982 MAX_CGROUP_ROOT_NAMELEN - 1,
983 GFP_KERNEL);
984 if (!opts->name)
985 return -ENOMEM;
987 continue;
990 for_each_subsys(ss, i) {
991 if (strcmp(token, ss->legacy_name))
992 continue;
993 if (!cgroup_ssid_enabled(i))
994 continue;
995 if (cgroup1_ssid_disabled(i))
996 continue;
998 /* Mutually exclusive option 'all' + subsystem name */
999 if (all_ss)
1000 return -EINVAL;
1001 opts->subsys_mask |= (1 << i);
1002 one_ss = true;
1004 break;
1006 if (i == CGROUP_SUBSYS_COUNT)
1007 return -ENOENT;
1011 * If the 'all' option was specified select all the subsystems,
1012 * otherwise if 'none', 'name=' and a subsystem name options were
1013 * not specified, let's default to 'all'
1015 if (all_ss || (!one_ss && !opts->none && !opts->name))
1016 for_each_subsys(ss, i)
1017 if (cgroup_ssid_enabled(i) && !cgroup1_ssid_disabled(i))
1018 opts->subsys_mask |= (1 << i);
1021 * We either have to specify by name or by subsystems. (So all
1022 * empty hierarchies must have a name).
1024 if (!opts->subsys_mask && !opts->name)
1025 return -EINVAL;
1028 * Option noprefix was introduced just for backward compatibility
1029 * with the old cpuset, so we allow noprefix only if mounting just
1030 * the cpuset subsystem.
1032 if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask))
1033 return -EINVAL;
1035 /* Can't specify "none" and some subsystems */
1036 if (opts->subsys_mask && opts->none)
1037 return -EINVAL;
1039 return 0;
1042 static int cgroup1_remount(struct kernfs_root *kf_root, int *flags, char *data)
1044 int ret = 0;
1045 struct cgroup_root *root = cgroup_root_from_kf(kf_root);
1046 struct cgroup_sb_opts opts;
1047 u16 added_mask, removed_mask;
1049 cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
1051 /* See what subsystems are wanted */
1052 ret = parse_cgroupfs_options(data, &opts);
1053 if (ret)
1054 goto out_unlock;
1056 if (opts.subsys_mask != root->subsys_mask || opts.release_agent)
1057 pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n",
1058 task_tgid_nr(current), current->comm);
1060 added_mask = opts.subsys_mask & ~root->subsys_mask;
1061 removed_mask = root->subsys_mask & ~opts.subsys_mask;
1063 /* Don't allow flags or name to change at remount */
1064 if ((opts.flags ^ root->flags) ||
1065 (opts.name && strcmp(opts.name, root->name))) {
1066 pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n",
1067 opts.flags, opts.name ?: "", root->flags, root->name);
1068 ret = -EINVAL;
1069 goto out_unlock;
1072 /* remounting is not allowed for populated hierarchies */
1073 if (!list_empty(&root->cgrp.self.children)) {
1074 ret = -EBUSY;
1075 goto out_unlock;
1078 ret = rebind_subsystems(root, added_mask);
1079 if (ret)
1080 goto out_unlock;
1082 WARN_ON(rebind_subsystems(&cgrp_dfl_root, removed_mask));
1084 if (opts.release_agent) {
1085 spin_lock(&release_agent_path_lock);
1086 strcpy(root->release_agent_path, opts.release_agent);
1087 spin_unlock(&release_agent_path_lock);
1090 trace_cgroup_remount(root);
1092 out_unlock:
1093 kfree(opts.release_agent);
1094 kfree(opts.name);
1095 mutex_unlock(&cgroup_mutex);
1096 return ret;
1099 struct kernfs_syscall_ops cgroup1_kf_syscall_ops = {
1100 .rename = cgroup1_rename,
1101 .show_options = cgroup1_show_options,
1102 .remount_fs = cgroup1_remount,
1103 .mkdir = cgroup_mkdir,
1104 .rmdir = cgroup_rmdir,
1105 .show_path = cgroup_show_path,
1108 struct dentry *cgroup1_mount(struct file_system_type *fs_type, int flags,
1109 void *data, unsigned long magic,
1110 struct cgroup_namespace *ns)
1112 struct super_block *pinned_sb = NULL;
1113 struct cgroup_sb_opts opts;
1114 struct cgroup_root *root;
1115 struct cgroup_subsys *ss;
1116 struct dentry *dentry;
1117 int i, ret;
1118 bool new_root = false;
1120 cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
1122 /* First find the desired set of subsystems */
1123 ret = parse_cgroupfs_options(data, &opts);
1124 if (ret)
1125 goto out_unlock;
1128 * Destruction of cgroup root is asynchronous, so subsystems may
1129 * still be dying after the previous unmount. Let's drain the
1130 * dying subsystems. We just need to ensure that the ones
1131 * unmounted previously finish dying and don't care about new ones
1132 * starting. Testing ref liveliness is good enough.
1134 for_each_subsys(ss, i) {
1135 if (!(opts.subsys_mask & (1 << i)) ||
1136 ss->root == &cgrp_dfl_root)
1137 continue;
1139 if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) {
1140 mutex_unlock(&cgroup_mutex);
1141 msleep(10);
1142 ret = restart_syscall();
1143 goto out_free;
1145 cgroup_put(&ss->root->cgrp);
1148 for_each_root(root) {
1149 bool name_match = false;
1151 if (root == &cgrp_dfl_root)
1152 continue;
1155 * If we asked for a name then it must match. Also, if
1156 * name matches but sybsys_mask doesn't, we should fail.
1157 * Remember whether name matched.
1159 if (opts.name) {
1160 if (strcmp(opts.name, root->name))
1161 continue;
1162 name_match = true;
1166 * If we asked for subsystems (or explicitly for no
1167 * subsystems) then they must match.
1169 if ((opts.subsys_mask || opts.none) &&
1170 (opts.subsys_mask != root->subsys_mask)) {
1171 if (!name_match)
1172 continue;
1173 ret = -EBUSY;
1174 goto out_unlock;
1177 if (root->flags ^ opts.flags)
1178 pr_warn("new mount options do not match the existing superblock, will be ignored\n");
1181 * We want to reuse @root whose lifetime is governed by its
1182 * ->cgrp. Let's check whether @root is alive and keep it
1183 * that way. As cgroup_kill_sb() can happen anytime, we
1184 * want to block it by pinning the sb so that @root doesn't
1185 * get killed before mount is complete.
1187 * With the sb pinned, tryget_live can reliably indicate
1188 * whether @root can be reused. If it's being killed,
1189 * drain it. We can use wait_queue for the wait but this
1190 * path is super cold. Let's just sleep a bit and retry.
1192 pinned_sb = kernfs_pin_sb(root->kf_root, NULL);
1193 if (IS_ERR(pinned_sb) ||
1194 !percpu_ref_tryget_live(&root->cgrp.self.refcnt)) {
1195 mutex_unlock(&cgroup_mutex);
1196 if (!IS_ERR_OR_NULL(pinned_sb))
1197 deactivate_super(pinned_sb);
1198 msleep(10);
1199 ret = restart_syscall();
1200 goto out_free;
1203 ret = 0;
1204 goto out_unlock;
1208 * No such thing, create a new one. name= matching without subsys
1209 * specification is allowed for already existing hierarchies but we
1210 * can't create new one without subsys specification.
1212 if (!opts.subsys_mask && !opts.none) {
1213 ret = -EINVAL;
1214 goto out_unlock;
1217 /* Hierarchies may only be created in the initial cgroup namespace. */
1218 if (ns != &init_cgroup_ns) {
1219 ret = -EPERM;
1220 goto out_unlock;
1223 root = kzalloc(sizeof(*root), GFP_KERNEL);
1224 if (!root) {
1225 ret = -ENOMEM;
1226 goto out_unlock;
1228 new_root = true;
1230 init_cgroup_root(root, &opts);
1232 ret = cgroup_setup_root(root, opts.subsys_mask, PERCPU_REF_INIT_DEAD);
1233 if (ret)
1234 cgroup_free_root(root);
1236 out_unlock:
1237 mutex_unlock(&cgroup_mutex);
1238 out_free:
1239 kfree(opts.release_agent);
1240 kfree(opts.name);
1242 if (ret)
1243 return ERR_PTR(ret);
1245 dentry = cgroup_do_mount(&cgroup_fs_type, flags, root,
1246 CGROUP_SUPER_MAGIC, ns);
1249 * There's a race window after we release cgroup_mutex and before
1250 * allocating a superblock. Make sure a concurrent process won't
1251 * be able to re-use the root during this window by delaying the
1252 * initialization of root refcnt.
1254 if (new_root) {
1255 mutex_lock(&cgroup_mutex);
1256 percpu_ref_reinit(&root->cgrp.self.refcnt);
1257 mutex_unlock(&cgroup_mutex);
1261 * If @pinned_sb, we're reusing an existing root and holding an
1262 * extra ref on its sb. Mount is complete. Put the extra ref.
1264 if (pinned_sb)
1265 deactivate_super(pinned_sb);
1267 return dentry;
1270 static int __init cgroup1_wq_init(void)
1273 * Used to destroy pidlists and separate to serve as flush domain.
1274 * Cap @max_active to 1 too.
1276 cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy",
1277 0, 1);
1278 BUG_ON(!cgroup_pidlist_destroy_wq);
1279 return 0;
1281 core_initcall(cgroup1_wq_init);
1283 static int __init cgroup_no_v1(char *str)
1285 struct cgroup_subsys *ss;
1286 char *token;
1287 int i;
1289 while ((token = strsep(&str, ",")) != NULL) {
1290 if (!*token)
1291 continue;
1293 if (!strcmp(token, "all")) {
1294 cgroup_no_v1_mask = U16_MAX;
1295 break;
1298 for_each_subsys(ss, i) {
1299 if (strcmp(token, ss->name) &&
1300 strcmp(token, ss->legacy_name))
1301 continue;
1303 cgroup_no_v1_mask |= 1 << i;
1306 return 1;
1308 __setup("cgroup_no_v1=", cgroup_no_v1);