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>
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);
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;
57 mutex_lock(&cgroup_mutex);
58 percpu_down_write(&cgroup_threadgroup_rwsem);
60 struct cgroup *from_cgrp;
62 if (root == &cgrp_dfl_root)
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);
73 percpu_up_write(&cgroup_threadgroup_rwsem);
74 mutex_unlock(&cgroup_mutex);
78 EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
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;
99 if (cgroup_on_dfl(to))
102 if (!cgroup_may_migrate_to(to))
105 mutex_lock(&cgroup_mutex);
107 percpu_down_write(&cgroup_threadgroup_rwsem);
109 /* all tasks in @from are being moved, all csets are source */
110 spin_lock_irq(&css_set_lock);
111 list_for_each_entry(link, &from->cset_links, cset_link)
112 cgroup_migrate_add_src(link->cset, to, &mgctx);
113 spin_unlock_irq(&css_set_lock);
115 ret = cgroup_migrate_prepare_dst(&mgctx);
120 * Migrate tasks one-by-one until @from is empty. This fails iff
121 * ->can_attach() fails.
124 css_task_iter_start(&from->self, &it);
125 task = css_task_iter_next(&it);
127 get_task_struct(task);
128 css_task_iter_end(&it);
131 ret = cgroup_migrate(task, false, &mgctx);
133 trace_cgroup_transfer_tasks(to, task, false);
134 put_task_struct(task);
136 } while (task && !ret);
138 cgroup_migrate_finish(&mgctx);
139 percpu_up_write(&cgroup_threadgroup_rwsem);
140 mutex_unlock(&cgroup_mutex);
145 * Stuff for reading the 'tasks'/'procs' files.
147 * Reading this file can return large amounts of data if a cgroup has
148 * *lots* of attached tasks. So it may need several calls to read(),
149 * but we cannot guarantee that the information we produce is correct
150 * unless we produce it entirely atomically.
154 /* which pidlist file are we talking about? */
155 enum cgroup_filetype {
161 * A pidlist is a list of pids that virtually represents the contents of one
162 * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
163 * a pair (one each for procs, tasks) for each pid namespace that's relevant
166 struct cgroup_pidlist {
168 * used to find which pidlist is wanted. doesn't change as long as
169 * this particular list stays in the list.
171 struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
174 /* how many elements the above list has */
176 /* each of these stored in a list by its cgroup */
177 struct list_head links;
178 /* pointer to the cgroup we belong to, for list removal purposes */
179 struct cgroup *owner;
180 /* for delayed destruction */
181 struct delayed_work destroy_dwork;
185 * The following two functions "fix" the issue where there are more pids
186 * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
187 * TODO: replace with a kernel-wide solution to this problem
189 #define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
190 static void *pidlist_allocate(int count)
192 if (PIDLIST_TOO_LARGE(count))
193 return vmalloc(count * sizeof(pid_t));
195 return kmalloc(count * sizeof(pid_t), GFP_KERNEL);
198 static void pidlist_free(void *p)
204 * Used to destroy all pidlists lingering waiting for destroy timer. None
205 * should be left afterwards.
207 void cgroup1_pidlist_destroy_all(struct cgroup *cgrp)
209 struct cgroup_pidlist *l, *tmp_l;
211 mutex_lock(&cgrp->pidlist_mutex);
212 list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links)
213 mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0);
214 mutex_unlock(&cgrp->pidlist_mutex);
216 flush_workqueue(cgroup_pidlist_destroy_wq);
217 BUG_ON(!list_empty(&cgrp->pidlists));
220 static void cgroup_pidlist_destroy_work_fn(struct work_struct *work)
222 struct delayed_work *dwork = to_delayed_work(work);
223 struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist,
225 struct cgroup_pidlist *tofree = NULL;
227 mutex_lock(&l->owner->pidlist_mutex);
230 * Destroy iff we didn't get queued again. The state won't change
231 * as destroy_dwork can only be queued while locked.
233 if (!delayed_work_pending(dwork)) {
235 pidlist_free(l->list);
236 put_pid_ns(l->key.ns);
240 mutex_unlock(&l->owner->pidlist_mutex);
245 * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
246 * Returns the number of unique elements.
248 static int pidlist_uniq(pid_t *list, int length)
253 * we presume the 0th element is unique, so i starts at 1. trivial
254 * edge cases first; no work needs to be done for either
256 if (length == 0 || length == 1)
258 /* src and dest walk down the list; dest counts unique elements */
259 for (src = 1; src < length; src++) {
260 /* find next unique element */
261 while (list[src] == list[src-1]) {
266 /* dest always points to where the next unique element goes */
267 list[dest] = list[src];
275 * The two pid files - task and cgroup.procs - guaranteed that the result
276 * is sorted, which forced this whole pidlist fiasco. As pid order is
277 * different per namespace, each namespace needs differently sorted list,
278 * making it impossible to use, for example, single rbtree of member tasks
279 * sorted by task pointer. As pidlists can be fairly large, allocating one
280 * per open file is dangerous, so cgroup had to implement shared pool of
281 * pidlists keyed by cgroup and namespace.
283 static int cmppid(const void *a, const void *b)
285 return *(pid_t *)a - *(pid_t *)b;
288 static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
289 enum cgroup_filetype type)
291 struct cgroup_pidlist *l;
292 /* don't need task_nsproxy() if we're looking at ourself */
293 struct pid_namespace *ns = task_active_pid_ns(current);
295 lockdep_assert_held(&cgrp->pidlist_mutex);
297 list_for_each_entry(l, &cgrp->pidlists, links)
298 if (l->key.type == type && l->key.ns == ns)
304 * find the appropriate pidlist for our purpose (given procs vs tasks)
305 * returns with the lock on that pidlist already held, and takes care
306 * of the use count, or returns NULL with no locks held if we're out of
309 static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp,
310 enum cgroup_filetype type)
312 struct cgroup_pidlist *l;
314 lockdep_assert_held(&cgrp->pidlist_mutex);
316 l = cgroup_pidlist_find(cgrp, type);
320 /* entry not found; create a new one */
321 l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
325 INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn);
327 /* don't need task_nsproxy() if we're looking at ourself */
328 l->key.ns = get_pid_ns(task_active_pid_ns(current));
330 list_add(&l->links, &cgrp->pidlists);
335 * cgroup_task_count - count the number of tasks in a cgroup.
336 * @cgrp: the cgroup in question
338 * Return the number of tasks in the cgroup. The returned number can be
339 * higher than the actual number of tasks due to css_set references from
340 * namespace roots and temporary usages.
342 static int cgroup_task_count(const struct cgroup *cgrp)
345 struct cgrp_cset_link *link;
347 spin_lock_irq(&css_set_lock);
348 list_for_each_entry(link, &cgrp->cset_links, cset_link)
349 count += atomic_read(&link->cset->refcount);
350 spin_unlock_irq(&css_set_lock);
355 * Load a cgroup's pidarray with either procs' tgids or tasks' pids
357 static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
358 struct cgroup_pidlist **lp)
362 int pid, n = 0; /* used for populating the array */
363 struct css_task_iter it;
364 struct task_struct *tsk;
365 struct cgroup_pidlist *l;
367 lockdep_assert_held(&cgrp->pidlist_mutex);
370 * If cgroup gets more users after we read count, we won't have
371 * enough space - tough. This race is indistinguishable to the
372 * caller from the case that the additional cgroup users didn't
373 * show up until sometime later on.
375 length = cgroup_task_count(cgrp);
376 array = pidlist_allocate(length);
379 /* now, populate the array */
380 css_task_iter_start(&cgrp->self, &it);
381 while ((tsk = css_task_iter_next(&it))) {
382 if (unlikely(n == length))
384 /* get tgid or pid for procs or tasks file respectively */
385 if (type == CGROUP_FILE_PROCS)
386 pid = task_tgid_vnr(tsk);
388 pid = task_pid_vnr(tsk);
389 if (pid > 0) /* make sure to only use valid results */
392 css_task_iter_end(&it);
394 /* now sort & (if procs) strip out duplicates */
395 sort(array, length, sizeof(pid_t), cmppid, NULL);
396 if (type == CGROUP_FILE_PROCS)
397 length = pidlist_uniq(array, length);
399 l = cgroup_pidlist_find_create(cgrp, type);
405 /* store array, freeing old if necessary */
406 pidlist_free(l->list);
414 * seq_file methods for the tasks/procs files. The seq_file position is the
415 * next pid to display; the seq_file iterator is a pointer to the pid
416 * in the cgroup->l->list array.
419 static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
422 * Initially we receive a position value that corresponds to
423 * one more than the last pid shown (or 0 on the first call or
424 * after a seek to the start). Use a binary-search to find the
425 * next pid to display, if any
427 struct kernfs_open_file *of = s->private;
428 struct cgroup *cgrp = seq_css(s)->cgroup;
429 struct cgroup_pidlist *l;
430 enum cgroup_filetype type = seq_cft(s)->private;
431 int index = 0, pid = *pos;
434 mutex_lock(&cgrp->pidlist_mutex);
437 * !NULL @of->priv indicates that this isn't the first start()
438 * after open. If the matching pidlist is around, we can use that.
439 * Look for it. Note that @of->priv can't be used directly. It
440 * could already have been destroyed.
443 of->priv = cgroup_pidlist_find(cgrp, type);
446 * Either this is the first start() after open or the matching
447 * pidlist has been destroyed inbetween. Create a new one.
450 ret = pidlist_array_load(cgrp, type,
451 (struct cgroup_pidlist **)&of->priv);
460 while (index < end) {
461 int mid = (index + end) / 2;
462 if (l->list[mid] == pid) {
465 } else if (l->list[mid] <= pid)
471 /* If we're off the end of the array, we're done */
472 if (index >= l->length)
474 /* Update the abstract position to be the actual pid that we found */
475 iter = l->list + index;
480 static void cgroup_pidlist_stop(struct seq_file *s, void *v)
482 struct kernfs_open_file *of = s->private;
483 struct cgroup_pidlist *l = of->priv;
486 mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork,
487 CGROUP_PIDLIST_DESTROY_DELAY);
488 mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex);
491 static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
493 struct kernfs_open_file *of = s->private;
494 struct cgroup_pidlist *l = of->priv;
496 pid_t *end = l->list + l->length;
498 * Advance to the next pid in the array. If this goes off the
510 static int cgroup_pidlist_show(struct seq_file *s, void *v)
512 seq_printf(s, "%d\n", *(int *)v);
517 static ssize_t cgroup_tasks_write(struct kernfs_open_file *of,
518 char *buf, size_t nbytes, loff_t off)
520 return __cgroup_procs_write(of, buf, nbytes, off, false);
523 static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
524 char *buf, size_t nbytes, loff_t off)
528 BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
530 cgrp = cgroup_kn_lock_live(of->kn, false);
533 spin_lock(&release_agent_path_lock);
534 strlcpy(cgrp->root->release_agent_path, strstrip(buf),
535 sizeof(cgrp->root->release_agent_path));
536 spin_unlock(&release_agent_path_lock);
537 cgroup_kn_unlock(of->kn);
541 static int cgroup_release_agent_show(struct seq_file *seq, void *v)
543 struct cgroup *cgrp = seq_css(seq)->cgroup;
545 spin_lock(&release_agent_path_lock);
546 seq_puts(seq, cgrp->root->release_agent_path);
547 spin_unlock(&release_agent_path_lock);
552 static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
554 seq_puts(seq, "0\n");
558 static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,
561 return notify_on_release(css->cgroup);
564 static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css,
565 struct cftype *cft, u64 val)
568 set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
570 clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
574 static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css,
577 return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
580 static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
581 struct cftype *cft, u64 val)
584 set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
586 clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
590 /* cgroup core interface files for the legacy hierarchies */
591 struct cftype cgroup1_base_files[] = {
593 .name = "cgroup.procs",
594 .seq_start = cgroup_pidlist_start,
595 .seq_next = cgroup_pidlist_next,
596 .seq_stop = cgroup_pidlist_stop,
597 .seq_show = cgroup_pidlist_show,
598 .private = CGROUP_FILE_PROCS,
599 .write = cgroup_procs_write,
602 .name = "cgroup.clone_children",
603 .read_u64 = cgroup_clone_children_read,
604 .write_u64 = cgroup_clone_children_write,
607 .name = "cgroup.sane_behavior",
608 .flags = CFTYPE_ONLY_ON_ROOT,
609 .seq_show = cgroup_sane_behavior_show,
613 .seq_start = cgroup_pidlist_start,
614 .seq_next = cgroup_pidlist_next,
615 .seq_stop = cgroup_pidlist_stop,
616 .seq_show = cgroup_pidlist_show,
617 .private = CGROUP_FILE_TASKS,
618 .write = cgroup_tasks_write,
621 .name = "notify_on_release",
622 .read_u64 = cgroup_read_notify_on_release,
623 .write_u64 = cgroup_write_notify_on_release,
626 .name = "release_agent",
627 .flags = CFTYPE_ONLY_ON_ROOT,
628 .seq_show = cgroup_release_agent_show,
629 .write = cgroup_release_agent_write,
630 .max_write_len = PATH_MAX - 1,
635 /* Display information about each subsystem and each hierarchy */
636 static int proc_cgroupstats_show(struct seq_file *m, void *v)
638 struct cgroup_subsys *ss;
641 seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
643 * ideally we don't want subsystems moving around while we do this.
644 * cgroup_mutex is also necessary to guarantee an atomic snapshot of
645 * subsys/hierarchy state.
647 mutex_lock(&cgroup_mutex);
649 for_each_subsys(ss, i)
650 seq_printf(m, "%s\t%d\t%d\t%d\n",
651 ss->legacy_name, ss->root->hierarchy_id,
652 atomic_read(&ss->root->nr_cgrps),
653 cgroup_ssid_enabled(i));
655 mutex_unlock(&cgroup_mutex);
659 static int cgroupstats_open(struct inode *inode, struct file *file)
661 return single_open(file, proc_cgroupstats_show, NULL);
664 const struct file_operations proc_cgroupstats_operations = {
665 .open = cgroupstats_open,
668 .release = single_release,
672 * cgroupstats_build - build and fill cgroupstats
673 * @stats: cgroupstats to fill information into
674 * @dentry: A dentry entry belonging to the cgroup for which stats have
677 * Build and fill cgroupstats so that taskstats can export it to user
680 int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
682 struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
684 struct css_task_iter it;
685 struct task_struct *tsk;
687 /* it should be kernfs_node belonging to cgroupfs and is a directory */
688 if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
689 kernfs_type(kn) != KERNFS_DIR)
692 mutex_lock(&cgroup_mutex);
695 * We aren't being called from kernfs and there's no guarantee on
696 * @kn->priv's validity. For this and css_tryget_online_from_dir(),
697 * @kn->priv is RCU safe. Let's do the RCU dancing.
700 cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv);
701 if (!cgrp || cgroup_is_dead(cgrp)) {
703 mutex_unlock(&cgroup_mutex);
708 css_task_iter_start(&cgrp->self, &it);
709 while ((tsk = css_task_iter_next(&it))) {
710 switch (tsk->state) {
714 case TASK_INTERRUPTIBLE:
715 stats->nr_sleeping++;
717 case TASK_UNINTERRUPTIBLE:
718 stats->nr_uninterruptible++;
724 if (delayacct_is_task_waiting_on_io(tsk))
729 css_task_iter_end(&it);
731 mutex_unlock(&cgroup_mutex);
735 void cgroup1_check_for_release(struct cgroup *cgrp)
737 if (notify_on_release(cgrp) && !cgroup_is_populated(cgrp) &&
738 !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp))
739 schedule_work(&cgrp->release_agent_work);
743 * Notify userspace when a cgroup is released, by running the
744 * configured release agent with the name of the cgroup (path
745 * relative to the root of cgroup file system) as the argument.
747 * Most likely, this user command will try to rmdir this cgroup.
749 * This races with the possibility that some other task will be
750 * attached to this cgroup before it is removed, or that some other
751 * user task will 'mkdir' a child cgroup of this cgroup. That's ok.
752 * The presumed 'rmdir' will fail quietly if this cgroup is no longer
753 * unused, and this cgroup will be reprieved from its death sentence,
754 * to continue to serve a useful existence. Next time it's released,
755 * we will get notified again, if it still has 'notify_on_release' set.
757 * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
758 * means only wait until the task is successfully execve()'d. The
759 * separate release agent task is forked by call_usermodehelper(),
760 * then control in this thread returns here, without waiting for the
761 * release agent task. We don't bother to wait because the caller of
762 * this routine has no use for the exit status of the release agent
763 * task, so no sense holding our caller up for that.
765 void cgroup1_release_agent(struct work_struct *work)
767 struct cgroup *cgrp =
768 container_of(work, struct cgroup, release_agent_work);
769 char *pathbuf = NULL, *agentbuf = NULL;
770 char *argv[3], *envp[3];
773 mutex_lock(&cgroup_mutex);
775 pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
776 agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL);
777 if (!pathbuf || !agentbuf)
780 spin_lock_irq(&css_set_lock);
781 ret = cgroup_path_ns_locked(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns);
782 spin_unlock_irq(&css_set_lock);
783 if (ret < 0 || ret >= PATH_MAX)
790 /* minimal command environment */
792 envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
795 mutex_unlock(&cgroup_mutex);
796 call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
799 mutex_unlock(&cgroup_mutex);
806 * cgroup_rename - Only allow simple rename of directories in place.
808 static int cgroup1_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
809 const char *new_name_str)
811 struct cgroup *cgrp = kn->priv;
814 if (kernfs_type(kn) != KERNFS_DIR)
816 if (kn->parent != new_parent)
820 * We're gonna grab cgroup_mutex which nests outside kernfs
821 * active_ref. kernfs_rename() doesn't require active_ref
822 * protection. Break them before grabbing cgroup_mutex.
824 kernfs_break_active_protection(new_parent);
825 kernfs_break_active_protection(kn);
827 mutex_lock(&cgroup_mutex);
829 ret = kernfs_rename(kn, new_parent, new_name_str);
831 trace_cgroup_rename(cgrp);
833 mutex_unlock(&cgroup_mutex);
835 kernfs_unbreak_active_protection(kn);
836 kernfs_unbreak_active_protection(new_parent);
840 static int cgroup1_show_options(struct seq_file *seq, struct kernfs_root *kf_root)
842 struct cgroup_root *root = cgroup_root_from_kf(kf_root);
843 struct cgroup_subsys *ss;
846 for_each_subsys(ss, ssid)
847 if (root->subsys_mask & (1 << ssid))
848 seq_show_option(seq, ss->legacy_name, NULL);
849 if (root->flags & CGRP_ROOT_NOPREFIX)
850 seq_puts(seq, ",noprefix");
851 if (root->flags & CGRP_ROOT_XATTR)
852 seq_puts(seq, ",xattr");
854 spin_lock(&release_agent_path_lock);
855 if (strlen(root->release_agent_path))
856 seq_show_option(seq, "release_agent",
857 root->release_agent_path);
858 spin_unlock(&release_agent_path_lock);
860 if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags))
861 seq_puts(seq, ",clone_children");
862 if (strlen(root->name))
863 seq_show_option(seq, "name", root->name);
867 static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
869 char *token, *o = data;
870 bool all_ss = false, one_ss = false;
872 struct cgroup_subsys *ss;
876 #ifdef CONFIG_CPUSETS
877 mask = ~((u16)1 << cpuset_cgrp_id);
880 memset(opts, 0, sizeof(*opts));
882 while ((token = strsep(&o, ",")) != NULL) {
887 if (!strcmp(token, "none")) {
888 /* Explicitly have no subsystems */
892 if (!strcmp(token, "all")) {
893 /* Mutually exclusive option 'all' + subsystem name */
899 if (!strcmp(token, "noprefix")) {
900 opts->flags |= CGRP_ROOT_NOPREFIX;
903 if (!strcmp(token, "clone_children")) {
904 opts->cpuset_clone_children = true;
907 if (!strcmp(token, "xattr")) {
908 opts->flags |= CGRP_ROOT_XATTR;
911 if (!strncmp(token, "release_agent=", 14)) {
912 /* Specifying two release agents is forbidden */
913 if (opts->release_agent)
915 opts->release_agent =
916 kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL);
917 if (!opts->release_agent)
921 if (!strncmp(token, "name=", 5)) {
922 const char *name = token + 5;
923 /* Can't specify an empty name */
926 /* Must match [\w.-]+ */
927 for (i = 0; i < strlen(name); i++) {
931 if ((c == '.') || (c == '-') || (c == '_'))
935 /* Specifying two names is forbidden */
938 opts->name = kstrndup(name,
939 MAX_CGROUP_ROOT_NAMELEN - 1,
947 for_each_subsys(ss, i) {
948 if (strcmp(token, ss->legacy_name))
950 if (!cgroup_ssid_enabled(i))
952 if (cgroup1_ssid_disabled(i))
955 /* Mutually exclusive option 'all' + subsystem name */
958 opts->subsys_mask |= (1 << i);
963 if (i == CGROUP_SUBSYS_COUNT)
968 * If the 'all' option was specified select all the subsystems,
969 * otherwise if 'none', 'name=' and a subsystem name options were
970 * not specified, let's default to 'all'
972 if (all_ss || (!one_ss && !opts->none && !opts->name))
973 for_each_subsys(ss, i)
974 if (cgroup_ssid_enabled(i) && !cgroup1_ssid_disabled(i))
975 opts->subsys_mask |= (1 << i);
978 * We either have to specify by name or by subsystems. (So all
979 * empty hierarchies must have a name).
981 if (!opts->subsys_mask && !opts->name)
985 * Option noprefix was introduced just for backward compatibility
986 * with the old cpuset, so we allow noprefix only if mounting just
987 * the cpuset subsystem.
989 if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask))
992 /* Can't specify "none" and some subsystems */
993 if (opts->subsys_mask && opts->none)
999 static int cgroup1_remount(struct kernfs_root *kf_root, int *flags, char *data)
1002 struct cgroup_root *root = cgroup_root_from_kf(kf_root);
1003 struct cgroup_sb_opts opts;
1004 u16 added_mask, removed_mask;
1006 cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
1008 /* See what subsystems are wanted */
1009 ret = parse_cgroupfs_options(data, &opts);
1013 if (opts.subsys_mask != root->subsys_mask || opts.release_agent)
1014 pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n",
1015 task_tgid_nr(current), current->comm);
1017 added_mask = opts.subsys_mask & ~root->subsys_mask;
1018 removed_mask = root->subsys_mask & ~opts.subsys_mask;
1020 /* Don't allow flags or name to change at remount */
1021 if ((opts.flags ^ root->flags) ||
1022 (opts.name && strcmp(opts.name, root->name))) {
1023 pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n",
1024 opts.flags, opts.name ?: "", root->flags, root->name);
1029 /* remounting is not allowed for populated hierarchies */
1030 if (!list_empty(&root->cgrp.self.children)) {
1035 ret = rebind_subsystems(root, added_mask);
1039 WARN_ON(rebind_subsystems(&cgrp_dfl_root, removed_mask));
1041 if (opts.release_agent) {
1042 spin_lock(&release_agent_path_lock);
1043 strcpy(root->release_agent_path, opts.release_agent);
1044 spin_unlock(&release_agent_path_lock);
1047 trace_cgroup_remount(root);
1050 kfree(opts.release_agent);
1052 mutex_unlock(&cgroup_mutex);
1056 struct kernfs_syscall_ops cgroup1_kf_syscall_ops = {
1057 .rename = cgroup1_rename,
1058 .show_options = cgroup1_show_options,
1059 .remount_fs = cgroup1_remount,
1060 .mkdir = cgroup_mkdir,
1061 .rmdir = cgroup_rmdir,
1062 .show_path = cgroup_show_path,
1065 struct dentry *cgroup1_mount(struct file_system_type *fs_type, int flags,
1066 void *data, unsigned long magic,
1067 struct cgroup_namespace *ns)
1069 struct super_block *pinned_sb = NULL;
1070 struct cgroup_sb_opts opts;
1071 struct cgroup_root *root;
1072 struct cgroup_subsys *ss;
1073 struct dentry *dentry;
1076 cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
1078 /* First find the desired set of subsystems */
1079 ret = parse_cgroupfs_options(data, &opts);
1084 * Destruction of cgroup root is asynchronous, so subsystems may
1085 * still be dying after the previous unmount. Let's drain the
1086 * dying subsystems. We just need to ensure that the ones
1087 * unmounted previously finish dying and don't care about new ones
1088 * starting. Testing ref liveliness is good enough.
1090 for_each_subsys(ss, i) {
1091 if (!(opts.subsys_mask & (1 << i)) ||
1092 ss->root == &cgrp_dfl_root)
1095 if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) {
1096 mutex_unlock(&cgroup_mutex);
1098 ret = restart_syscall();
1101 cgroup_put(&ss->root->cgrp);
1104 for_each_root(root) {
1105 bool name_match = false;
1107 if (root == &cgrp_dfl_root)
1111 * If we asked for a name then it must match. Also, if
1112 * name matches but sybsys_mask doesn't, we should fail.
1113 * Remember whether name matched.
1116 if (strcmp(opts.name, root->name))
1122 * If we asked for subsystems (or explicitly for no
1123 * subsystems) then they must match.
1125 if ((opts.subsys_mask || opts.none) &&
1126 (opts.subsys_mask != root->subsys_mask)) {
1133 if (root->flags ^ opts.flags)
1134 pr_warn("new mount options do not match the existing superblock, will be ignored\n");
1137 * We want to reuse @root whose lifetime is governed by its
1138 * ->cgrp. Let's check whether @root is alive and keep it
1139 * that way. As cgroup_kill_sb() can happen anytime, we
1140 * want to block it by pinning the sb so that @root doesn't
1141 * get killed before mount is complete.
1143 * With the sb pinned, tryget_live can reliably indicate
1144 * whether @root can be reused. If it's being killed,
1145 * drain it. We can use wait_queue for the wait but this
1146 * path is super cold. Let's just sleep a bit and retry.
1148 pinned_sb = kernfs_pin_sb(root->kf_root, NULL);
1149 if (IS_ERR(pinned_sb) ||
1150 !percpu_ref_tryget_live(&root->cgrp.self.refcnt)) {
1151 mutex_unlock(&cgroup_mutex);
1152 if (!IS_ERR_OR_NULL(pinned_sb))
1153 deactivate_super(pinned_sb);
1155 ret = restart_syscall();
1164 * No such thing, create a new one. name= matching without subsys
1165 * specification is allowed for already existing hierarchies but we
1166 * can't create new one without subsys specification.
1168 if (!opts.subsys_mask && !opts.none) {
1173 /* Hierarchies may only be created in the initial cgroup namespace. */
1174 if (ns != &init_cgroup_ns) {
1179 root = kzalloc(sizeof(*root), GFP_KERNEL);
1185 init_cgroup_root(root, &opts);
1187 ret = cgroup_setup_root(root, opts.subsys_mask);
1189 cgroup_free_root(root);
1192 mutex_unlock(&cgroup_mutex);
1194 kfree(opts.release_agent);
1198 return ERR_PTR(ret);
1200 dentry = cgroup_do_mount(&cgroup_fs_type, flags, root,
1201 CGROUP_SUPER_MAGIC, ns);
1204 * If @pinned_sb, we're reusing an existing root and holding an
1205 * extra ref on its sb. Mount is complete. Put the extra ref.
1208 deactivate_super(pinned_sb);
1213 static int __init cgroup1_wq_init(void)
1216 * Used to destroy pidlists and separate to serve as flush domain.
1217 * Cap @max_active to 1 too.
1219 cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy",
1221 BUG_ON(!cgroup_pidlist_destroy_wq);
1224 core_initcall(cgroup1_wq_init);
1226 static int __init cgroup_no_v1(char *str)
1228 struct cgroup_subsys *ss;
1232 while ((token = strsep(&str, ",")) != NULL) {
1236 if (!strcmp(token, "all")) {
1237 cgroup_no_v1_mask = U16_MAX;
1241 for_each_subsys(ss, i) {
1242 if (strcmp(token, ss->name) &&
1243 strcmp(token, ss->legacy_name))
1246 cgroup_no_v1_mask |= 1 << i;
1251 __setup("cgroup_no_v1=", cgroup_no_v1);
1254 #ifdef CONFIG_CGROUP_DEBUG
1255 static struct cgroup_subsys_state *
1256 debug_css_alloc(struct cgroup_subsys_state *parent_css)
1258 struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
1261 return ERR_PTR(-ENOMEM);
1266 static void debug_css_free(struct cgroup_subsys_state *css)
1271 static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
1274 return cgroup_task_count(css->cgroup);
1277 static u64 current_css_set_read(struct cgroup_subsys_state *css,
1280 return (u64)(unsigned long)current->cgroups;
1283 static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
1289 count = atomic_read(&task_css_set(current)->refcount);
1294 static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
1296 struct cgrp_cset_link *link;
1297 struct css_set *cset;
1300 name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
1304 spin_lock_irq(&css_set_lock);
1306 cset = rcu_dereference(current->cgroups);
1307 list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
1308 struct cgroup *c = link->cgrp;
1310 cgroup_name(c, name_buf, NAME_MAX + 1);
1311 seq_printf(seq, "Root %d group %s\n",
1312 c->root->hierarchy_id, name_buf);
1315 spin_unlock_irq(&css_set_lock);
1320 #define MAX_TASKS_SHOWN_PER_CSS 25
1321 static int cgroup_css_links_read(struct seq_file *seq, void *v)
1323 struct cgroup_subsys_state *css = seq_css(seq);
1324 struct cgrp_cset_link *link;
1326 spin_lock_irq(&css_set_lock);
1327 list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
1328 struct css_set *cset = link->cset;
1329 struct task_struct *task;
1332 seq_printf(seq, "css_set %pK\n", cset);
1334 list_for_each_entry(task, &cset->tasks, cg_list) {
1335 if (count++ > MAX_TASKS_SHOWN_PER_CSS)
1337 seq_printf(seq, " task %d\n", task_pid_vnr(task));
1340 list_for_each_entry(task, &cset->mg_tasks, cg_list) {
1341 if (count++ > MAX_TASKS_SHOWN_PER_CSS)
1343 seq_printf(seq, " task %d\n", task_pid_vnr(task));
1347 seq_puts(seq, " ...\n");
1349 spin_unlock_irq(&css_set_lock);
1353 static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft)
1355 return (!cgroup_is_populated(css->cgroup) &&
1356 !css_has_online_children(&css->cgroup->self));
1359 static struct cftype debug_files[] = {
1361 .name = "taskcount",
1362 .read_u64 = debug_taskcount_read,
1366 .name = "current_css_set",
1367 .read_u64 = current_css_set_read,
1371 .name = "current_css_set_refcount",
1372 .read_u64 = current_css_set_refcount_read,
1376 .name = "current_css_set_cg_links",
1377 .seq_show = current_css_set_cg_links_read,
1381 .name = "cgroup_css_links",
1382 .seq_show = cgroup_css_links_read,
1386 .name = "releasable",
1387 .read_u64 = releasable_read,
1393 struct cgroup_subsys debug_cgrp_subsys = {
1394 .css_alloc = debug_css_alloc,
1395 .css_free = debug_css_free,
1396 .legacy_cftypes = debug_files,
1398 #endif /* CONFIG_CGROUP_DEBUG */