v4.19.13 snapshot.
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
new file mode 100644
index 0000000..51063e7
--- /dev/null
+++ b/kernel/cgroup/cgroup-v1.c
@@ -0,0 +1,1308 @@
+#include "cgroup-internal.h"
+
+#include <linux/ctype.h>
+#include <linux/kmod.h>
+#include <linux/sort.h>
+#include <linux/delay.h>
+#include <linux/mm.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/task.h>
+#include <linux/magic.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/delayacct.h>
+#include <linux/pid_namespace.h>
+#include <linux/cgroupstats.h>
+
+#include <trace/events/cgroup.h>
+
+/*
+ * pidlists linger the following amount before being destroyed. The goal
+ * is avoiding frequent destruction in the middle of consecutive read calls
+ * Expiring in the middle is a performance problem not a correctness one.
+ * 1 sec should be enough.
+ */
+#define CGROUP_PIDLIST_DESTROY_DELAY HZ
+
+/* Controllers blocked by the commandline in v1 */
+static u16 cgroup_no_v1_mask;
+
+/*
+ * pidlist destructions need to be flushed on cgroup destruction. Use a
+ * separate workqueue as flush domain.
+ */
+static struct workqueue_struct *cgroup_pidlist_destroy_wq;
+
+/*
+ * Protects cgroup_subsys->release_agent_path. Modifying it also requires
+ * cgroup_mutex. Reading requires either cgroup_mutex or this spinlock.
+ */
+static DEFINE_SPINLOCK(release_agent_path_lock);
+
+bool cgroup1_ssid_disabled(int ssid)
+{
+ return cgroup_no_v1_mask & (1 << ssid);
+}
+
+/**
+ * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
+ * @from: attach to all cgroups of a given task
+ * @tsk: the task to be attached
+ */
+int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
+{
+ struct cgroup_root *root;
+ int retval = 0;
+
+ mutex_lock(&cgroup_mutex);
+ percpu_down_write(&cgroup_threadgroup_rwsem);
+ for_each_root(root) {
+ struct cgroup *from_cgrp;
+
+ if (root == &cgrp_dfl_root)
+ continue;
+
+ spin_lock_irq(&css_set_lock);
+ from_cgrp = task_cgroup_from_root(from, root);
+ spin_unlock_irq(&css_set_lock);
+
+ retval = cgroup_attach_task(from_cgrp, tsk, false);
+ if (retval)
+ break;
+ }
+ percpu_up_write(&cgroup_threadgroup_rwsem);
+ mutex_unlock(&cgroup_mutex);
+
+ return retval;
+}
+EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
+
+/**
+ * cgroup_trasnsfer_tasks - move tasks from one cgroup to another
+ * @to: cgroup to which the tasks will be moved
+ * @from: cgroup in which the tasks currently reside
+ *
+ * Locking rules between cgroup_post_fork() and the migration path
+ * guarantee that, if a task is forking while being migrated, the new child
+ * is guaranteed to be either visible in the source cgroup after the
+ * parent's migration is complete or put into the target cgroup. No task
+ * can slip out of migration through forking.
+ */
+int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
+{
+ DEFINE_CGROUP_MGCTX(mgctx);
+ struct cgrp_cset_link *link;
+ struct css_task_iter it;
+ struct task_struct *task;
+ int ret;
+
+ if (cgroup_on_dfl(to))
+ return -EINVAL;
+
+ ret = cgroup_migrate_vet_dst(to);
+ if (ret)
+ return ret;
+
+ mutex_lock(&cgroup_mutex);
+
+ percpu_down_write(&cgroup_threadgroup_rwsem);
+
+ /* all tasks in @from are being moved, all csets are source */
+ spin_lock_irq(&css_set_lock);
+ list_for_each_entry(link, &from->cset_links, cset_link)
+ cgroup_migrate_add_src(link->cset, to, &mgctx);
+ spin_unlock_irq(&css_set_lock);
+
+ ret = cgroup_migrate_prepare_dst(&mgctx);
+ if (ret)
+ goto out_err;
+
+ /*
+ * Migrate tasks one-by-one until @from is empty. This fails iff
+ * ->can_attach() fails.
+ */
+ do {
+ css_task_iter_start(&from->self, 0, &it);
+
+ do {
+ task = css_task_iter_next(&it);
+ } while (task && (task->flags & PF_EXITING));
+
+ if (task)
+ get_task_struct(task);
+ css_task_iter_end(&it);
+
+ if (task) {
+ ret = cgroup_migrate(task, false, &mgctx);
+ if (!ret)
+ TRACE_CGROUP_PATH(transfer_tasks, to, task, false);
+ put_task_struct(task);
+ }
+ } while (task && !ret);
+out_err:
+ cgroup_migrate_finish(&mgctx);
+ percpu_up_write(&cgroup_threadgroup_rwsem);
+ mutex_unlock(&cgroup_mutex);
+ return ret;
+}
+
+/*
+ * Stuff for reading the 'tasks'/'procs' files.
+ *
+ * Reading this file can return large amounts of data if a cgroup has
+ * *lots* of attached tasks. So it may need several calls to read(),
+ * but we cannot guarantee that the information we produce is correct
+ * unless we produce it entirely atomically.
+ *
+ */
+
+/* which pidlist file are we talking about? */
+enum cgroup_filetype {
+ CGROUP_FILE_PROCS,
+ CGROUP_FILE_TASKS,
+};
+
+/*
+ * A pidlist is a list of pids that virtually represents the contents of one
+ * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
+ * a pair (one each for procs, tasks) for each pid namespace that's relevant
+ * to the cgroup.
+ */
+struct cgroup_pidlist {
+ /*
+ * used to find which pidlist is wanted. doesn't change as long as
+ * this particular list stays in the list.
+ */
+ struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
+ /* array of xids */
+ pid_t *list;
+ /* how many elements the above list has */
+ int length;
+ /* each of these stored in a list by its cgroup */
+ struct list_head links;
+ /* pointer to the cgroup we belong to, for list removal purposes */
+ struct cgroup *owner;
+ /* for delayed destruction */
+ struct delayed_work destroy_dwork;
+};
+
+/*
+ * The following two functions "fix" the issue where there are more pids
+ * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
+ * TODO: replace with a kernel-wide solution to this problem
+ */
+#define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
+static void *pidlist_allocate(int count)
+{
+ if (PIDLIST_TOO_LARGE(count))
+ return vmalloc(array_size(count, sizeof(pid_t)));
+ else
+ return kmalloc_array(count, sizeof(pid_t), GFP_KERNEL);
+}
+
+static void pidlist_free(void *p)
+{
+ kvfree(p);
+}
+
+/*
+ * Used to destroy all pidlists lingering waiting for destroy timer. None
+ * should be left afterwards.
+ */
+void cgroup1_pidlist_destroy_all(struct cgroup *cgrp)
+{
+ struct cgroup_pidlist *l, *tmp_l;
+
+ mutex_lock(&cgrp->pidlist_mutex);
+ list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links)
+ mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0);
+ mutex_unlock(&cgrp->pidlist_mutex);
+
+ flush_workqueue(cgroup_pidlist_destroy_wq);
+ BUG_ON(!list_empty(&cgrp->pidlists));
+}
+
+static void cgroup_pidlist_destroy_work_fn(struct work_struct *work)
+{
+ struct delayed_work *dwork = to_delayed_work(work);
+ struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist,
+ destroy_dwork);
+ struct cgroup_pidlist *tofree = NULL;
+
+ mutex_lock(&l->owner->pidlist_mutex);
+
+ /*
+ * Destroy iff we didn't get queued again. The state won't change
+ * as destroy_dwork can only be queued while locked.
+ */
+ if (!delayed_work_pending(dwork)) {
+ list_del(&l->links);
+ pidlist_free(l->list);
+ put_pid_ns(l->key.ns);
+ tofree = l;
+ }
+
+ mutex_unlock(&l->owner->pidlist_mutex);
+ kfree(tofree);
+}
+
+/*
+ * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
+ * Returns the number of unique elements.
+ */
+static int pidlist_uniq(pid_t *list, int length)
+{
+ int src, dest = 1;
+
+ /*
+ * we presume the 0th element is unique, so i starts at 1. trivial
+ * edge cases first; no work needs to be done for either
+ */
+ if (length == 0 || length == 1)
+ return length;
+ /* src and dest walk down the list; dest counts unique elements */
+ for (src = 1; src < length; src++) {
+ /* find next unique element */
+ while (list[src] == list[src-1]) {
+ src++;
+ if (src == length)
+ goto after;
+ }
+ /* dest always points to where the next unique element goes */
+ list[dest] = list[src];
+ dest++;
+ }
+after:
+ return dest;
+}
+
+/*
+ * The two pid files - task and cgroup.procs - guaranteed that the result
+ * is sorted, which forced this whole pidlist fiasco. As pid order is
+ * different per namespace, each namespace needs differently sorted list,
+ * making it impossible to use, for example, single rbtree of member tasks
+ * sorted by task pointer. As pidlists can be fairly large, allocating one
+ * per open file is dangerous, so cgroup had to implement shared pool of
+ * pidlists keyed by cgroup and namespace.
+ */
+static int cmppid(const void *a, const void *b)
+{
+ return *(pid_t *)a - *(pid_t *)b;
+}
+
+static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
+ enum cgroup_filetype type)
+{
+ struct cgroup_pidlist *l;
+ /* don't need task_nsproxy() if we're looking at ourself */
+ struct pid_namespace *ns = task_active_pid_ns(current);
+
+ lockdep_assert_held(&cgrp->pidlist_mutex);
+
+ list_for_each_entry(l, &cgrp->pidlists, links)
+ if (l->key.type == type && l->key.ns == ns)
+ return l;
+ return NULL;
+}
+
+/*
+ * find the appropriate pidlist for our purpose (given procs vs tasks)
+ * returns with the lock on that pidlist already held, and takes care
+ * of the use count, or returns NULL with no locks held if we're out of
+ * memory.
+ */
+static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp,
+ enum cgroup_filetype type)
+{
+ struct cgroup_pidlist *l;
+
+ lockdep_assert_held(&cgrp->pidlist_mutex);
+
+ l = cgroup_pidlist_find(cgrp, type);
+ if (l)
+ return l;
+
+ /* entry not found; create a new one */
+ l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
+ if (!l)
+ return l;
+
+ INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn);
+ l->key.type = type;
+ /* don't need task_nsproxy() if we're looking at ourself */
+ l->key.ns = get_pid_ns(task_active_pid_ns(current));
+ l->owner = cgrp;
+ list_add(&l->links, &cgrp->pidlists);
+ return l;
+}
+
+/**
+ * cgroup_task_count - count the number of tasks in a cgroup.
+ * @cgrp: the cgroup in question
+ */
+int cgroup_task_count(const struct cgroup *cgrp)
+{
+ int count = 0;
+ struct cgrp_cset_link *link;
+
+ spin_lock_irq(&css_set_lock);
+ list_for_each_entry(link, &cgrp->cset_links, cset_link)
+ count += link->cset->nr_tasks;
+ spin_unlock_irq(&css_set_lock);
+ return count;
+}
+
+/*
+ * Load a cgroup's pidarray with either procs' tgids or tasks' pids
+ */
+static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
+ struct cgroup_pidlist **lp)
+{
+ pid_t *array;
+ int length;
+ int pid, n = 0; /* used for populating the array */
+ struct css_task_iter it;
+ struct task_struct *tsk;
+ struct cgroup_pidlist *l;
+
+ lockdep_assert_held(&cgrp->pidlist_mutex);
+
+ /*
+ * If cgroup gets more users after we read count, we won't have
+ * enough space - tough. This race is indistinguishable to the
+ * caller from the case that the additional cgroup users didn't
+ * show up until sometime later on.
+ */
+ length = cgroup_task_count(cgrp);
+ array = pidlist_allocate(length);
+ if (!array)
+ return -ENOMEM;
+ /* now, populate the array */
+ css_task_iter_start(&cgrp->self, 0, &it);
+ while ((tsk = css_task_iter_next(&it))) {
+ if (unlikely(n == length))
+ break;
+ /* get tgid or pid for procs or tasks file respectively */
+ if (type == CGROUP_FILE_PROCS)
+ pid = task_tgid_vnr(tsk);
+ else
+ pid = task_pid_vnr(tsk);
+ if (pid > 0) /* make sure to only use valid results */
+ array[n++] = pid;
+ }
+ css_task_iter_end(&it);
+ length = n;
+ /* now sort & (if procs) strip out duplicates */
+ sort(array, length, sizeof(pid_t), cmppid, NULL);
+ if (type == CGROUP_FILE_PROCS)
+ length = pidlist_uniq(array, length);
+
+ l = cgroup_pidlist_find_create(cgrp, type);
+ if (!l) {
+ pidlist_free(array);
+ return -ENOMEM;
+ }
+
+ /* store array, freeing old if necessary */
+ pidlist_free(l->list);
+ l->list = array;
+ l->length = length;
+ *lp = l;
+ return 0;
+}
+
+/*
+ * seq_file methods for the tasks/procs files. The seq_file position is the
+ * next pid to display; the seq_file iterator is a pointer to the pid
+ * in the cgroup->l->list array.
+ */
+
+static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
+{
+ /*
+ * Initially we receive a position value that corresponds to
+ * one more than the last pid shown (or 0 on the first call or
+ * after a seek to the start). Use a binary-search to find the
+ * next pid to display, if any
+ */
+ struct kernfs_open_file *of = s->private;
+ struct cgroup *cgrp = seq_css(s)->cgroup;
+ struct cgroup_pidlist *l;
+ enum cgroup_filetype type = seq_cft(s)->private;
+ int index = 0, pid = *pos;
+ int *iter, ret;
+
+ mutex_lock(&cgrp->pidlist_mutex);
+
+ /*
+ * !NULL @of->priv indicates that this isn't the first start()
+ * after open. If the matching pidlist is around, we can use that.
+ * Look for it. Note that @of->priv can't be used directly. It
+ * could already have been destroyed.
+ */
+ if (of->priv)
+ of->priv = cgroup_pidlist_find(cgrp, type);
+
+ /*
+ * Either this is the first start() after open or the matching
+ * pidlist has been destroyed inbetween. Create a new one.
+ */
+ if (!of->priv) {
+ ret = pidlist_array_load(cgrp, type,
+ (struct cgroup_pidlist **)&of->priv);
+ if (ret)
+ return ERR_PTR(ret);
+ }
+ l = of->priv;
+
+ if (pid) {
+ int end = l->length;
+
+ while (index < end) {
+ int mid = (index + end) / 2;
+ if (l->list[mid] == pid) {
+ index = mid;
+ break;
+ } else if (l->list[mid] <= pid)
+ index = mid + 1;
+ else
+ end = mid;
+ }
+ }
+ /* If we're off the end of the array, we're done */
+ if (index >= l->length)
+ return NULL;
+ /* Update the abstract position to be the actual pid that we found */
+ iter = l->list + index;
+ *pos = *iter;
+ return iter;
+}
+
+static void cgroup_pidlist_stop(struct seq_file *s, void *v)
+{
+ struct kernfs_open_file *of = s->private;
+ struct cgroup_pidlist *l = of->priv;
+
+ if (l)
+ mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork,
+ CGROUP_PIDLIST_DESTROY_DELAY);
+ mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex);
+}
+
+static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
+{
+ struct kernfs_open_file *of = s->private;
+ struct cgroup_pidlist *l = of->priv;
+ pid_t *p = v;
+ pid_t *end = l->list + l->length;
+ /*
+ * Advance to the next pid in the array. If this goes off the
+ * end, we're done
+ */
+ p++;
+ if (p >= end) {
+ return NULL;
+ } else {
+ *pos = *p;
+ return p;
+ }
+}
+
+static int cgroup_pidlist_show(struct seq_file *s, void *v)
+{
+ seq_printf(s, "%d\n", *(int *)v);
+
+ return 0;
+}
+
+static ssize_t __cgroup1_procs_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off,
+ bool threadgroup)
+{
+ struct cgroup *cgrp;
+ struct task_struct *task;
+ const struct cred *cred, *tcred;
+ ssize_t ret;
+
+ cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!cgrp)
+ return -ENODEV;
+
+ task = cgroup_procs_write_start(buf, threadgroup);
+ ret = PTR_ERR_OR_ZERO(task);
+ if (ret)
+ goto out_unlock;
+
+ /*
+ * Even if we're attaching all tasks in the thread group, we only
+ * need to check permissions on one of them.
+ */
+ cred = current_cred();
+ tcred = get_task_cred(task);
+ if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
+ !uid_eq(cred->euid, tcred->uid) &&
+ !uid_eq(cred->euid, tcred->suid))
+ ret = -EACCES;
+ put_cred(tcred);
+ if (ret)
+ goto out_finish;
+
+ ret = cgroup_attach_task(cgrp, task, threadgroup);
+
+out_finish:
+ cgroup_procs_write_finish(task);
+out_unlock:
+ cgroup_kn_unlock(of->kn);
+
+ return ret ?: nbytes;
+}
+
+static ssize_t cgroup1_procs_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ return __cgroup1_procs_write(of, buf, nbytes, off, true);
+}
+
+static ssize_t cgroup1_tasks_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ return __cgroup1_procs_write(of, buf, nbytes, off, false);
+}
+
+static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ struct cgroup *cgrp;
+
+ BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
+
+ cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!cgrp)
+ return -ENODEV;
+ spin_lock(&release_agent_path_lock);
+ strlcpy(cgrp->root->release_agent_path, strstrip(buf),
+ sizeof(cgrp->root->release_agent_path));
+ spin_unlock(&release_agent_path_lock);
+ cgroup_kn_unlock(of->kn);
+ return nbytes;
+}
+
+static int cgroup_release_agent_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+
+ spin_lock(&release_agent_path_lock);
+ seq_puts(seq, cgrp->root->release_agent_path);
+ spin_unlock(&release_agent_path_lock);
+ seq_putc(seq, '\n');
+ return 0;
+}
+
+static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
+{
+ seq_puts(seq, "0\n");
+ return 0;
+}
+
+static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ return notify_on_release(css->cgroup);
+}
+
+static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css,
+ struct cftype *cft, u64 val)
+{
+ if (val)
+ set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
+ else
+ clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
+ return 0;
+}
+
+static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
+}
+
+static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
+ struct cftype *cft, u64 val)
+{
+ if (val)
+ set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
+ else
+ clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
+ return 0;
+}
+
+/* cgroup core interface files for the legacy hierarchies */
+struct cftype cgroup1_base_files[] = {
+ {
+ .name = "cgroup.procs",
+ .seq_start = cgroup_pidlist_start,
+ .seq_next = cgroup_pidlist_next,
+ .seq_stop = cgroup_pidlist_stop,
+ .seq_show = cgroup_pidlist_show,
+ .private = CGROUP_FILE_PROCS,
+ .write = cgroup1_procs_write,
+ },
+ {
+ .name = "cgroup.clone_children",
+ .read_u64 = cgroup_clone_children_read,
+ .write_u64 = cgroup_clone_children_write,
+ },
+ {
+ .name = "cgroup.sane_behavior",
+ .flags = CFTYPE_ONLY_ON_ROOT,
+ .seq_show = cgroup_sane_behavior_show,
+ },
+ {
+ .name = "tasks",
+ .seq_start = cgroup_pidlist_start,
+ .seq_next = cgroup_pidlist_next,
+ .seq_stop = cgroup_pidlist_stop,
+ .seq_show = cgroup_pidlist_show,
+ .private = CGROUP_FILE_TASKS,
+ .write = cgroup1_tasks_write,
+ },
+ {
+ .name = "notify_on_release",
+ .read_u64 = cgroup_read_notify_on_release,
+ .write_u64 = cgroup_write_notify_on_release,
+ },
+ {
+ .name = "release_agent",
+ .flags = CFTYPE_ONLY_ON_ROOT,
+ .seq_show = cgroup_release_agent_show,
+ .write = cgroup_release_agent_write,
+ .max_write_len = PATH_MAX - 1,
+ },
+ { } /* terminate */
+};
+
+/* Display information about each subsystem and each hierarchy */
+int proc_cgroupstats_show(struct seq_file *m, void *v)
+{
+ struct cgroup_subsys *ss;
+ int i;
+
+ seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
+ /*
+ * ideally we don't want subsystems moving around while we do this.
+ * cgroup_mutex is also necessary to guarantee an atomic snapshot of
+ * subsys/hierarchy state.
+ */
+ mutex_lock(&cgroup_mutex);
+
+ for_each_subsys(ss, i)
+ seq_printf(m, "%s\t%d\t%d\t%d\n",
+ ss->legacy_name, ss->root->hierarchy_id,
+ atomic_read(&ss->root->nr_cgrps),
+ cgroup_ssid_enabled(i));
+
+ mutex_unlock(&cgroup_mutex);
+ return 0;
+}
+
+/**
+ * cgroupstats_build - build and fill cgroupstats
+ * @stats: cgroupstats to fill information into
+ * @dentry: A dentry entry belonging to the cgroup for which stats have
+ * been requested.
+ *
+ * Build and fill cgroupstats so that taskstats can export it to user
+ * space.
+ */
+int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
+{
+ struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
+ struct cgroup *cgrp;
+ struct css_task_iter it;
+ struct task_struct *tsk;
+
+ /* it should be kernfs_node belonging to cgroupfs and is a directory */
+ if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
+ kernfs_type(kn) != KERNFS_DIR)
+ return -EINVAL;
+
+ mutex_lock(&cgroup_mutex);
+
+ /*
+ * We aren't being called from kernfs and there's no guarantee on
+ * @kn->priv's validity. For this and css_tryget_online_from_dir(),
+ * @kn->priv is RCU safe. Let's do the RCU dancing.
+ */
+ rcu_read_lock();
+ cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv);
+ if (!cgrp || cgroup_is_dead(cgrp)) {
+ rcu_read_unlock();
+ mutex_unlock(&cgroup_mutex);
+ return -ENOENT;
+ }
+ rcu_read_unlock();
+
+ css_task_iter_start(&cgrp->self, 0, &it);
+ while ((tsk = css_task_iter_next(&it))) {
+ switch (tsk->state) {
+ case TASK_RUNNING:
+ stats->nr_running++;
+ break;
+ case TASK_INTERRUPTIBLE:
+ stats->nr_sleeping++;
+ break;
+ case TASK_UNINTERRUPTIBLE:
+ stats->nr_uninterruptible++;
+ break;
+ case TASK_STOPPED:
+ stats->nr_stopped++;
+ break;
+ default:
+ if (delayacct_is_task_waiting_on_io(tsk))
+ stats->nr_io_wait++;
+ break;
+ }
+ }
+ css_task_iter_end(&it);
+
+ mutex_unlock(&cgroup_mutex);
+ return 0;
+}
+
+void cgroup1_check_for_release(struct cgroup *cgrp)
+{
+ if (notify_on_release(cgrp) && !cgroup_is_populated(cgrp) &&
+ !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp))
+ schedule_work(&cgrp->release_agent_work);
+}
+
+/*
+ * Notify userspace when a cgroup is released, by running the
+ * configured release agent with the name of the cgroup (path
+ * relative to the root of cgroup file system) as the argument.
+ *
+ * Most likely, this user command will try to rmdir this cgroup.
+ *
+ * This races with the possibility that some other task will be
+ * attached to this cgroup before it is removed, or that some other
+ * user task will 'mkdir' a child cgroup of this cgroup. That's ok.
+ * The presumed 'rmdir' will fail quietly if this cgroup is no longer
+ * unused, and this cgroup will be reprieved from its death sentence,
+ * to continue to serve a useful existence. Next time it's released,
+ * we will get notified again, if it still has 'notify_on_release' set.
+ *
+ * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
+ * means only wait until the task is successfully execve()'d. The
+ * separate release agent task is forked by call_usermodehelper(),
+ * then control in this thread returns here, without waiting for the
+ * release agent task. We don't bother to wait because the caller of
+ * this routine has no use for the exit status of the release agent
+ * task, so no sense holding our caller up for that.
+ */
+void cgroup1_release_agent(struct work_struct *work)
+{
+ struct cgroup *cgrp =
+ container_of(work, struct cgroup, release_agent_work);
+ char *pathbuf = NULL, *agentbuf = NULL;
+ char *argv[3], *envp[3];
+ int ret;
+
+ mutex_lock(&cgroup_mutex);
+
+ pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
+ agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL);
+ if (!pathbuf || !agentbuf)
+ goto out;
+
+ spin_lock_irq(&css_set_lock);
+ ret = cgroup_path_ns_locked(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns);
+ spin_unlock_irq(&css_set_lock);
+ if (ret < 0 || ret >= PATH_MAX)
+ goto out;
+
+ argv[0] = agentbuf;
+ argv[1] = pathbuf;
+ argv[2] = NULL;
+
+ /* minimal command environment */
+ envp[0] = "HOME=/";
+ envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
+ envp[2] = NULL;
+
+ mutex_unlock(&cgroup_mutex);
+ call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
+ goto out_free;
+out:
+ mutex_unlock(&cgroup_mutex);
+out_free:
+ kfree(agentbuf);
+ kfree(pathbuf);
+}
+
+/*
+ * cgroup_rename - Only allow simple rename of directories in place.
+ */
+static int cgroup1_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
+ const char *new_name_str)
+{
+ struct cgroup *cgrp = kn->priv;
+ int ret;
+
+ if (kernfs_type(kn) != KERNFS_DIR)
+ return -ENOTDIR;
+ if (kn->parent != new_parent)
+ return -EIO;
+
+ /*
+ * We're gonna grab cgroup_mutex which nests outside kernfs
+ * active_ref. kernfs_rename() doesn't require active_ref
+ * protection. Break them before grabbing cgroup_mutex.
+ */
+ kernfs_break_active_protection(new_parent);
+ kernfs_break_active_protection(kn);
+
+ mutex_lock(&cgroup_mutex);
+
+ ret = kernfs_rename(kn, new_parent, new_name_str);
+ if (!ret)
+ TRACE_CGROUP_PATH(rename, cgrp);
+
+ mutex_unlock(&cgroup_mutex);
+
+ kernfs_unbreak_active_protection(kn);
+ kernfs_unbreak_active_protection(new_parent);
+ return ret;
+}
+
+static int cgroup1_show_options(struct seq_file *seq, struct kernfs_root *kf_root)
+{
+ struct cgroup_root *root = cgroup_root_from_kf(kf_root);
+ struct cgroup_subsys *ss;
+ int ssid;
+
+ for_each_subsys(ss, ssid)
+ if (root->subsys_mask & (1 << ssid))
+ seq_show_option(seq, ss->legacy_name, NULL);
+ if (root->flags & CGRP_ROOT_NOPREFIX)
+ seq_puts(seq, ",noprefix");
+ if (root->flags & CGRP_ROOT_XATTR)
+ seq_puts(seq, ",xattr");
+ if (root->flags & CGRP_ROOT_CPUSET_V2_MODE)
+ seq_puts(seq, ",cpuset_v2_mode");
+
+ spin_lock(&release_agent_path_lock);
+ if (strlen(root->release_agent_path))
+ seq_show_option(seq, "release_agent",
+ root->release_agent_path);
+ spin_unlock(&release_agent_path_lock);
+
+ if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags))
+ seq_puts(seq, ",clone_children");
+ if (strlen(root->name))
+ seq_show_option(seq, "name", root->name);
+ return 0;
+}
+
+static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
+{
+ char *token, *o = data;
+ bool all_ss = false, one_ss = false;
+ u16 mask = U16_MAX;
+ struct cgroup_subsys *ss;
+ int nr_opts = 0;
+ int i;
+
+#ifdef CONFIG_CPUSETS
+ mask = ~((u16)1 << cpuset_cgrp_id);
+#endif
+
+ memset(opts, 0, sizeof(*opts));
+
+ while ((token = strsep(&o, ",")) != NULL) {
+ nr_opts++;
+
+ if (!*token)
+ return -EINVAL;
+ if (!strcmp(token, "none")) {
+ /* Explicitly have no subsystems */
+ opts->none = true;
+ continue;
+ }
+ if (!strcmp(token, "all")) {
+ /* Mutually exclusive option 'all' + subsystem name */
+ if (one_ss)
+ return -EINVAL;
+ all_ss = true;
+ continue;
+ }
+ if (!strcmp(token, "noprefix")) {
+ opts->flags |= CGRP_ROOT_NOPREFIX;
+ continue;
+ }
+ if (!strcmp(token, "clone_children")) {
+ opts->cpuset_clone_children = true;
+ continue;
+ }
+ if (!strcmp(token, "cpuset_v2_mode")) {
+ opts->flags |= CGRP_ROOT_CPUSET_V2_MODE;
+ continue;
+ }
+ if (!strcmp(token, "xattr")) {
+ opts->flags |= CGRP_ROOT_XATTR;
+ continue;
+ }
+ if (!strncmp(token, "release_agent=", 14)) {
+ /* Specifying two release agents is forbidden */
+ if (opts->release_agent)
+ return -EINVAL;
+ opts->release_agent =
+ kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL);
+ if (!opts->release_agent)
+ return -ENOMEM;
+ continue;
+ }
+ if (!strncmp(token, "name=", 5)) {
+ const char *name = token + 5;
+ /* Can't specify an empty name */
+ if (!strlen(name))
+ return -EINVAL;
+ /* Must match [\w.-]+ */
+ for (i = 0; i < strlen(name); i++) {
+ char c = name[i];
+ if (isalnum(c))
+ continue;
+ if ((c == '.') || (c == '-') || (c == '_'))
+ continue;
+ return -EINVAL;
+ }
+ /* Specifying two names is forbidden */
+ if (opts->name)
+ return -EINVAL;
+ opts->name = kstrndup(name,
+ MAX_CGROUP_ROOT_NAMELEN - 1,
+ GFP_KERNEL);
+ if (!opts->name)
+ return -ENOMEM;
+
+ continue;
+ }
+
+ for_each_subsys(ss, i) {
+ if (strcmp(token, ss->legacy_name))
+ continue;
+ if (!cgroup_ssid_enabled(i))
+ continue;
+ if (cgroup1_ssid_disabled(i))
+ continue;
+
+ /* Mutually exclusive option 'all' + subsystem name */
+ if (all_ss)
+ return -EINVAL;
+ opts->subsys_mask |= (1 << i);
+ one_ss = true;
+
+ break;
+ }
+ if (i == CGROUP_SUBSYS_COUNT)
+ return -ENOENT;
+ }
+
+ /*
+ * If the 'all' option was specified select all the subsystems,
+ * otherwise if 'none', 'name=' and a subsystem name options were
+ * not specified, let's default to 'all'
+ */
+ if (all_ss || (!one_ss && !opts->none && !opts->name))
+ for_each_subsys(ss, i)
+ if (cgroup_ssid_enabled(i) && !cgroup1_ssid_disabled(i))
+ opts->subsys_mask |= (1 << i);
+
+ /*
+ * We either have to specify by name or by subsystems. (So all
+ * empty hierarchies must have a name).
+ */
+ if (!opts->subsys_mask && !opts->name)
+ return -EINVAL;
+
+ /*
+ * Option noprefix was introduced just for backward compatibility
+ * with the old cpuset, so we allow noprefix only if mounting just
+ * the cpuset subsystem.
+ */
+ if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask))
+ return -EINVAL;
+
+ /* Can't specify "none" and some subsystems */
+ if (opts->subsys_mask && opts->none)
+ return -EINVAL;
+
+ return 0;
+}
+
+static int cgroup1_remount(struct kernfs_root *kf_root, int *flags, char *data)
+{
+ int ret = 0;
+ struct cgroup_root *root = cgroup_root_from_kf(kf_root);
+ struct cgroup_sb_opts opts;
+ u16 added_mask, removed_mask;
+
+ cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
+
+ /* See what subsystems are wanted */
+ ret = parse_cgroupfs_options(data, &opts);
+ if (ret)
+ goto out_unlock;
+
+ if (opts.subsys_mask != root->subsys_mask || opts.release_agent)
+ pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n",
+ task_tgid_nr(current), current->comm);
+
+ added_mask = opts.subsys_mask & ~root->subsys_mask;
+ removed_mask = root->subsys_mask & ~opts.subsys_mask;
+
+ /* Don't allow flags or name to change at remount */
+ if ((opts.flags ^ root->flags) ||
+ (opts.name && strcmp(opts.name, root->name))) {
+ pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n",
+ opts.flags, opts.name ?: "", root->flags, root->name);
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ /* remounting is not allowed for populated hierarchies */
+ if (!list_empty(&root->cgrp.self.children)) {
+ ret = -EBUSY;
+ goto out_unlock;
+ }
+
+ ret = rebind_subsystems(root, added_mask);
+ if (ret)
+ goto out_unlock;
+
+ WARN_ON(rebind_subsystems(&cgrp_dfl_root, removed_mask));
+
+ if (opts.release_agent) {
+ spin_lock(&release_agent_path_lock);
+ strcpy(root->release_agent_path, opts.release_agent);
+ spin_unlock(&release_agent_path_lock);
+ }
+
+ trace_cgroup_remount(root);
+
+ out_unlock:
+ kfree(opts.release_agent);
+ kfree(opts.name);
+ mutex_unlock(&cgroup_mutex);
+ return ret;
+}
+
+struct kernfs_syscall_ops cgroup1_kf_syscall_ops = {
+ .rename = cgroup1_rename,
+ .show_options = cgroup1_show_options,
+ .remount_fs = cgroup1_remount,
+ .mkdir = cgroup_mkdir,
+ .rmdir = cgroup_rmdir,
+ .show_path = cgroup_show_path,
+};
+
+struct dentry *cgroup1_mount(struct file_system_type *fs_type, int flags,
+ void *data, unsigned long magic,
+ struct cgroup_namespace *ns)
+{
+ struct super_block *pinned_sb = NULL;
+ struct cgroup_sb_opts opts;
+ struct cgroup_root *root;
+ struct cgroup_subsys *ss;
+ struct dentry *dentry;
+ int i, ret;
+ bool new_root = false;
+
+ cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
+
+ /* First find the desired set of subsystems */
+ ret = parse_cgroupfs_options(data, &opts);
+ if (ret)
+ goto out_unlock;
+
+ /*
+ * Destruction of cgroup root is asynchronous, so subsystems may
+ * still be dying after the previous unmount. Let's drain the
+ * dying subsystems. We just need to ensure that the ones
+ * unmounted previously finish dying and don't care about new ones
+ * starting. Testing ref liveliness is good enough.
+ */
+ for_each_subsys(ss, i) {
+ if (!(opts.subsys_mask & (1 << i)) ||
+ ss->root == &cgrp_dfl_root)
+ continue;
+
+ if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) {
+ mutex_unlock(&cgroup_mutex);
+ msleep(10);
+ ret = restart_syscall();
+ goto out_free;
+ }
+ cgroup_put(&ss->root->cgrp);
+ }
+
+ for_each_root(root) {
+ bool name_match = false;
+
+ if (root == &cgrp_dfl_root)
+ continue;
+
+ /*
+ * If we asked for a name then it must match. Also, if
+ * name matches but sybsys_mask doesn't, we should fail.
+ * Remember whether name matched.
+ */
+ if (opts.name) {
+ if (strcmp(opts.name, root->name))
+ continue;
+ name_match = true;
+ }
+
+ /*
+ * If we asked for subsystems (or explicitly for no
+ * subsystems) then they must match.
+ */
+ if ((opts.subsys_mask || opts.none) &&
+ (opts.subsys_mask != root->subsys_mask)) {
+ if (!name_match)
+ continue;
+ ret = -EBUSY;
+ goto out_unlock;
+ }
+
+ if (root->flags ^ opts.flags)
+ pr_warn("new mount options do not match the existing superblock, will be ignored\n");
+
+ /*
+ * We want to reuse @root whose lifetime is governed by its
+ * ->cgrp. Let's check whether @root is alive and keep it
+ * that way. As cgroup_kill_sb() can happen anytime, we
+ * want to block it by pinning the sb so that @root doesn't
+ * get killed before mount is complete.
+ *
+ * With the sb pinned, tryget_live can reliably indicate
+ * whether @root can be reused. If it's being killed,
+ * drain it. We can use wait_queue for the wait but this
+ * path is super cold. Let's just sleep a bit and retry.
+ */
+ pinned_sb = kernfs_pin_sb(root->kf_root, NULL);
+ if (IS_ERR(pinned_sb) ||
+ !percpu_ref_tryget_live(&root->cgrp.self.refcnt)) {
+ mutex_unlock(&cgroup_mutex);
+ if (!IS_ERR_OR_NULL(pinned_sb))
+ deactivate_super(pinned_sb);
+ msleep(10);
+ ret = restart_syscall();
+ goto out_free;
+ }
+
+ ret = 0;
+ goto out_unlock;
+ }
+
+ /*
+ * No such thing, create a new one. name= matching without subsys
+ * specification is allowed for already existing hierarchies but we
+ * can't create new one without subsys specification.
+ */
+ if (!opts.subsys_mask && !opts.none) {
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ /* Hierarchies may only be created in the initial cgroup namespace. */
+ if (ns != &init_cgroup_ns) {
+ ret = -EPERM;
+ goto out_unlock;
+ }
+
+ root = kzalloc(sizeof(*root), GFP_KERNEL);
+ if (!root) {
+ ret = -ENOMEM;
+ goto out_unlock;
+ }
+ new_root = true;
+
+ init_cgroup_root(root, &opts);
+
+ ret = cgroup_setup_root(root, opts.subsys_mask, PERCPU_REF_INIT_DEAD);
+ if (ret)
+ cgroup_free_root(root);
+
+out_unlock:
+ mutex_unlock(&cgroup_mutex);
+out_free:
+ kfree(opts.release_agent);
+ kfree(opts.name);
+
+ if (ret)
+ return ERR_PTR(ret);
+
+ dentry = cgroup_do_mount(&cgroup_fs_type, flags, root,
+ CGROUP_SUPER_MAGIC, ns);
+
+ /*
+ * There's a race window after we release cgroup_mutex and before
+ * allocating a superblock. Make sure a concurrent process won't
+ * be able to re-use the root during this window by delaying the
+ * initialization of root refcnt.
+ */
+ if (new_root) {
+ mutex_lock(&cgroup_mutex);
+ percpu_ref_reinit(&root->cgrp.self.refcnt);
+ mutex_unlock(&cgroup_mutex);
+ }
+
+ /*
+ * If @pinned_sb, we're reusing an existing root and holding an
+ * extra ref on its sb. Mount is complete. Put the extra ref.
+ */
+ if (pinned_sb)
+ deactivate_super(pinned_sb);
+
+ return dentry;
+}
+
+static int __init cgroup1_wq_init(void)
+{
+ /*
+ * Used to destroy pidlists and separate to serve as flush domain.
+ * Cap @max_active to 1 too.
+ */
+ cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy",
+ 0, 1);
+ BUG_ON(!cgroup_pidlist_destroy_wq);
+ return 0;
+}
+core_initcall(cgroup1_wq_init);
+
+static int __init cgroup_no_v1(char *str)
+{
+ struct cgroup_subsys *ss;
+ char *token;
+ int i;
+
+ while ((token = strsep(&str, ",")) != NULL) {
+ if (!*token)
+ continue;
+
+ if (!strcmp(token, "all")) {
+ cgroup_no_v1_mask = U16_MAX;
+ break;
+ }
+
+ for_each_subsys(ss, i) {
+ if (strcmp(token, ss->name) &&
+ strcmp(token, ss->legacy_name))
+ continue;
+
+ cgroup_no_v1_mask |= 1 << i;
+ }
+ }
+ return 1;
+}
+__setup("cgroup_no_v1=", cgroup_no_v1);