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Diffstat (limited to 'kernel/cgroup/cgroup.c')
-rw-r--r--kernel/cgroup/cgroup.c355
1 files changed, 333 insertions, 22 deletions
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index a1d59af274a9..c396e701c206 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -162,6 +162,9 @@ static u16 cgrp_dfl_inhibit_ss_mask;
/* some controllers are implicitly enabled on the default hierarchy */
static u16 cgrp_dfl_implicit_ss_mask;
+/* some controllers can be threaded on the default hierarchy */
+static u16 cgrp_dfl_threaded_ss_mask;
+
/* The list of hierarchy roots */
LIST_HEAD(cgroup_roots);
static int cgroup_root_count;
@@ -335,14 +338,93 @@ static bool cgroup_is_threaded(struct cgroup *cgrp)
return cgrp->dom_cgrp != cgrp;
}
+/* can @cgrp host both domain and threaded children? */
+static bool cgroup_is_mixable(struct cgroup *cgrp)
+{
+ /*
+ * Root isn't under domain level resource control exempting it from
+ * the no-internal-process constraint, so it can serve as a thread
+ * root and a parent of resource domains at the same time.
+ */
+ return !cgroup_parent(cgrp);
+}
+
+/* can @cgrp become a thread root? should always be true for a thread root */
+static bool cgroup_can_be_thread_root(struct cgroup *cgrp)
+{
+ /* mixables don't care */
+ if (cgroup_is_mixable(cgrp))
+ return true;
+
+ /* domain roots can't be nested under threaded */
+ if (cgroup_is_threaded(cgrp))
+ return false;
+
+ /* can only have either domain or threaded children */
+ if (cgrp->nr_populated_domain_children)
+ return false;
+
+ /* and no domain controllers can be enabled */
+ if (cgrp->subtree_control & ~cgrp_dfl_threaded_ss_mask)
+ return false;
+
+ return true;
+}
+
+/* is @cgrp root of a threaded subtree? */
+static bool cgroup_is_thread_root(struct cgroup *cgrp)
+{
+ /* thread root should be a domain */
+ if (cgroup_is_threaded(cgrp))
+ return false;
+
+ /* a domain w/ threaded children is a thread root */
+ if (cgrp->nr_threaded_children)
+ return true;
+
+ /*
+ * A domain which has tasks and explicit threaded controllers
+ * enabled is a thread root.
+ */
+ if (cgroup_has_tasks(cgrp) &&
+ (cgrp->subtree_control & cgrp_dfl_threaded_ss_mask))
+ return true;
+
+ return false;
+}
+
+/* a domain which isn't connected to the root w/o brekage can't be used */
+static bool cgroup_is_valid_domain(struct cgroup *cgrp)
+{
+ /* the cgroup itself can be a thread root */
+ if (cgroup_is_threaded(cgrp))
+ return false;
+
+ /* but the ancestors can't be unless mixable */
+ while ((cgrp = cgroup_parent(cgrp))) {
+ if (!cgroup_is_mixable(cgrp) && cgroup_is_thread_root(cgrp))
+ return false;
+ if (cgroup_is_threaded(cgrp))
+ return false;
+ }
+
+ return true;
+}
+
/* subsystems visibly enabled on a cgroup */
static u16 cgroup_control(struct cgroup *cgrp)
{
struct cgroup *parent = cgroup_parent(cgrp);
u16 root_ss_mask = cgrp->root->subsys_mask;
- if (parent)
- return parent->subtree_control;
+ if (parent) {
+ u16 ss_mask = parent->subtree_control;
+
+ /* threaded cgroups can only have threaded controllers */
+ if (cgroup_is_threaded(cgrp))
+ ss_mask &= cgrp_dfl_threaded_ss_mask;
+ return ss_mask;
+ }
if (cgroup_on_dfl(cgrp))
root_ss_mask &= ~(cgrp_dfl_inhibit_ss_mask |
@@ -355,8 +437,14 @@ static u16 cgroup_ss_mask(struct cgroup *cgrp)
{
struct cgroup *parent = cgroup_parent(cgrp);
- if (parent)
- return parent->subtree_ss_mask;
+ if (parent) {
+ u16 ss_mask = parent->subtree_ss_mask;
+
+ /* threaded cgroups can only have threaded controllers */
+ if (cgroup_is_threaded(cgrp))
+ ss_mask &= cgrp_dfl_threaded_ss_mask;
+ return ss_mask;
+ }
return cgrp->root->subsys_mask;
}
@@ -2237,17 +2325,40 @@ out_release_tset:
}
/**
- * cgroup_may_migrate_to - verify whether a cgroup can be migration destination
+ * cgroup_migrate_vet_dst - verify whether a cgroup can be migration destination
* @dst_cgrp: destination cgroup to test
*
- * On the default hierarchy, except for the root, subtree_control must be
- * zero for migration destination cgroups with tasks so that child cgroups
- * don't compete against tasks.
+ * On the default hierarchy, except for the mixable, (possible) thread root
+ * and threaded cgroups, subtree_control must be zero for migration
+ * destination cgroups with tasks so that child cgroups don't compete
+ * against tasks.
*/
-bool cgroup_may_migrate_to(struct cgroup *dst_cgrp)
+int cgroup_migrate_vet_dst(struct cgroup *dst_cgrp)
{
- return !cgroup_on_dfl(dst_cgrp) || !cgroup_parent(dst_cgrp) ||
- !dst_cgrp->subtree_control;
+ /* v1 doesn't have any restriction */
+ if (!cgroup_on_dfl(dst_cgrp))
+ return 0;
+
+ /* verify @dst_cgrp can host resources */
+ if (!cgroup_is_valid_domain(dst_cgrp->dom_cgrp))
+ return -EOPNOTSUPP;
+
+ /* mixables don't care */
+ if (cgroup_is_mixable(dst_cgrp))
+ return 0;
+
+ /*
+ * If @dst_cgrp is already or can become a thread root or is
+ * threaded, it doesn't matter.
+ */
+ if (cgroup_can_be_thread_root(dst_cgrp) || cgroup_is_threaded(dst_cgrp))
+ return 0;
+
+ /* apply no-internal-process constraint */
+ if (dst_cgrp->subtree_control)
+ return -EBUSY;
+
+ return 0;
}
/**
@@ -2452,8 +2563,9 @@ int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
struct task_struct *task;
int ret;
- if (!cgroup_may_migrate_to(dst_cgrp))
- return -EBUSY;
+ ret = cgroup_migrate_vet_dst(dst_cgrp);
+ if (ret)
+ return ret;
/* look up all src csets */
spin_lock_irq(&css_set_lock);
@@ -2881,6 +2993,46 @@ static void cgroup_finalize_control(struct cgroup *cgrp, int ret)
cgroup_apply_control_disable(cgrp);
}
+static int cgroup_vet_subtree_control_enable(struct cgroup *cgrp, u16 enable)
+{
+ u16 domain_enable = enable & ~cgrp_dfl_threaded_ss_mask;
+
+ /* if nothing is getting enabled, nothing to worry about */
+ if (!enable)
+ return 0;
+
+ /* can @cgrp host any resources? */
+ if (!cgroup_is_valid_domain(cgrp->dom_cgrp))
+ return -EOPNOTSUPP;
+
+ /* mixables don't care */
+ if (cgroup_is_mixable(cgrp))
+ return 0;
+
+ if (domain_enable) {
+ /* can't enable domain controllers inside a thread subtree */
+ if (cgroup_is_thread_root(cgrp) || cgroup_is_threaded(cgrp))
+ return -EOPNOTSUPP;
+ } else {
+ /*
+ * Threaded controllers can handle internal competitions
+ * and are always allowed inside a (prospective) thread
+ * subtree.
+ */
+ if (cgroup_can_be_thread_root(cgrp) || cgroup_is_threaded(cgrp))
+ return 0;
+ }
+
+ /*
+ * Controllers can't be enabled for a cgroup with tasks to avoid
+ * child cgroups competing against tasks.
+ */
+ if (cgroup_has_tasks(cgrp))
+ return -EBUSY;
+
+ return 0;
+}
+
/* change the enabled child controllers for a cgroup in the default hierarchy */
static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
char *buf, size_t nbytes,
@@ -2956,14 +3108,9 @@ static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
goto out_unlock;
}
- /*
- * Except for the root, subtree_control must be zero for a cgroup
- * with tasks so that child cgroups don't compete against tasks.
- */
- if (enable && cgroup_parent(cgrp) && cgroup_has_tasks(cgrp)) {
- ret = -EBUSY;
+ ret = cgroup_vet_subtree_control_enable(cgrp, enable);
+ if (ret)
goto out_unlock;
- }
/* save and update control masks and prepare csses */
cgroup_save_control(cgrp);
@@ -2982,6 +3129,84 @@ out_unlock:
return ret ?: nbytes;
}
+static int cgroup_enable_threaded(struct cgroup *cgrp)
+{
+ struct cgroup *parent = cgroup_parent(cgrp);
+ struct cgroup *dom_cgrp = parent->dom_cgrp;
+ int ret;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ /* noop if already threaded */
+ if (cgroup_is_threaded(cgrp))
+ return 0;
+
+ /* we're joining the parent's domain, ensure its validity */
+ if (!cgroup_is_valid_domain(dom_cgrp) ||
+ !cgroup_can_be_thread_root(dom_cgrp))
+ return -EOPNOTSUPP;
+
+ /*
+ * Allow enabling thread mode only on empty cgroups to avoid
+ * implicit migrations and recursive operations.
+ */
+ if (cgroup_has_tasks(cgrp) || css_has_online_children(&cgrp->self))
+ return -EBUSY;
+
+ /*
+ * The following shouldn't cause actual migrations and should
+ * always succeed.
+ */
+ cgroup_save_control(cgrp);
+
+ cgrp->dom_cgrp = dom_cgrp;
+ ret = cgroup_apply_control(cgrp);
+ if (!ret)
+ parent->nr_threaded_children++;
+ else
+ cgrp->dom_cgrp = cgrp;
+
+ cgroup_finalize_control(cgrp, ret);
+ return ret;
+}
+
+static int cgroup_type_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+
+ if (cgroup_is_threaded(cgrp))
+ seq_puts(seq, "threaded\n");
+ else if (!cgroup_is_valid_domain(cgrp))
+ seq_puts(seq, "domain invalid\n");
+ else if (cgroup_is_thread_root(cgrp))
+ seq_puts(seq, "domain threaded\n");
+ else
+ seq_puts(seq, "domain\n");
+
+ return 0;
+}
+
+static ssize_t cgroup_type_write(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
+{
+ struct cgroup *cgrp;
+ int ret;
+
+ /* only switching to threaded mode is supported */
+ if (strcmp(strstrip(buf), "threaded"))
+ return -EINVAL;
+
+ cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!cgrp)
+ return -ENOENT;
+
+ /* threaded can only be enabled */
+ ret = cgroup_enable_threaded(cgrp);
+
+ cgroup_kn_unlock(of->kn);
+ return ret ?: nbytes;
+}
+
static int cgroup_events_show(struct seq_file *seq, void *v)
{
seq_printf(seq, "populated %d\n",
@@ -3867,12 +4092,12 @@ static void *cgroup_procs_next(struct seq_file *s, void *v, loff_t *pos)
return css_task_iter_next(it);
}
-static void *cgroup_procs_start(struct seq_file *s, loff_t *pos)
+static void *__cgroup_procs_start(struct seq_file *s, loff_t *pos,
+ unsigned int iter_flags)
{
struct kernfs_open_file *of = s->private;
struct cgroup *cgrp = seq_css(s)->cgroup;
struct css_task_iter *it = of->priv;
- unsigned iter_flags = CSS_TASK_ITER_PROCS | CSS_TASK_ITER_THREADED;
/*
* When a seq_file is seeked, it's always traversed sequentially
@@ -3895,6 +4120,23 @@ static void *cgroup_procs_start(struct seq_file *s, loff_t *pos)
return cgroup_procs_next(s, NULL, NULL);
}
+static void *cgroup_procs_start(struct seq_file *s, loff_t *pos)
+{
+ struct cgroup *cgrp = seq_css(s)->cgroup;
+
+ /*
+ * All processes of a threaded subtree belong to the domain cgroup
+ * of the subtree. Only threads can be distributed across the
+ * subtree. Reject reads on cgroup.procs in the subtree proper.
+ * They're always empty anyway.
+ */
+ if (cgroup_is_threaded(cgrp))
+ return ERR_PTR(-EOPNOTSUPP);
+
+ return __cgroup_procs_start(s, pos, CSS_TASK_ITER_PROCS |
+ CSS_TASK_ITER_THREADED);
+}
+
static int cgroup_procs_show(struct seq_file *s, void *v)
{
seq_printf(s, "%d\n", task_pid_vnr(v));
@@ -3974,9 +4216,64 @@ out_unlock:
return ret ?: nbytes;
}
+static void *cgroup_threads_start(struct seq_file *s, loff_t *pos)
+{
+ return __cgroup_procs_start(s, pos, 0);
+}
+
+static ssize_t cgroup_threads_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ struct cgroup *src_cgrp, *dst_cgrp;
+ struct task_struct *task;
+ ssize_t ret;
+
+ buf = strstrip(buf);
+
+ dst_cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!dst_cgrp)
+ return -ENODEV;
+
+ task = cgroup_procs_write_start(buf, false);
+ ret = PTR_ERR_OR_ZERO(task);
+ if (ret)
+ goto out_unlock;
+
+ /* find the source cgroup */
+ spin_lock_irq(&css_set_lock);
+ src_cgrp = task_cgroup_from_root(task, &cgrp_dfl_root);
+ spin_unlock_irq(&css_set_lock);
+
+ /* thread migrations follow the cgroup.procs delegation rule */
+ ret = cgroup_procs_write_permission(src_cgrp, dst_cgrp,
+ of->file->f_path.dentry->d_sb);
+ if (ret)
+ goto out_finish;
+
+ /* and must be contained in the same domain */
+ ret = -EOPNOTSUPP;
+ if (src_cgrp->dom_cgrp != dst_cgrp->dom_cgrp)
+ goto out_finish;
+
+ ret = cgroup_attach_task(dst_cgrp, task, false);
+
+out_finish:
+ cgroup_procs_write_finish(task);
+out_unlock:
+ cgroup_kn_unlock(of->kn);
+
+ return ret ?: nbytes;
+}
+
/* cgroup core interface files for the default hierarchy */
static struct cftype cgroup_base_files[] = {
{
+ .name = "cgroup.type",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .seq_show = cgroup_type_show,
+ .write = cgroup_type_write,
+ },
+ {
.name = "cgroup.procs",
.flags = CFTYPE_NS_DELEGATABLE,
.file_offset = offsetof(struct cgroup, procs_file),
@@ -3987,6 +4284,14 @@ static struct cftype cgroup_base_files[] = {
.write = cgroup_procs_write,
},
{
+ .name = "cgroup.threads",
+ .release = cgroup_procs_release,
+ .seq_start = cgroup_threads_start,
+ .seq_next = cgroup_procs_next,
+ .seq_show = cgroup_procs_show,
+ .write = cgroup_threads_write,
+ },
+ {
.name = "cgroup.controllers",
.seq_show = cgroup_controllers_show,
},
@@ -4753,11 +5058,17 @@ int __init cgroup_init(void)
cgrp_dfl_root.subsys_mask |= 1 << ss->id;
+ /* implicit controllers must be threaded too */
+ WARN_ON(ss->implicit_on_dfl && !ss->threaded);
+
if (ss->implicit_on_dfl)
cgrp_dfl_implicit_ss_mask |= 1 << ss->id;
else if (!ss->dfl_cftypes)
cgrp_dfl_inhibit_ss_mask |= 1 << ss->id;
+ if (ss->threaded)
+ cgrp_dfl_threaded_ss_mask |= 1 << ss->id;
+
if (ss->dfl_cftypes == ss->legacy_cftypes) {
WARN_ON(cgroup_add_cftypes(ss, ss->dfl_cftypes));
} else {
generated by cgit (git 2.34.1) at 2024-06-14 10:48:17 +0000