diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 3fdb21a390c154bceaf04ca0515c22ea4f0e10ac..9273d0969ebd6377a02cf0be189d34ea619afe3e 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -412,13 +412,13 @@ static void throtl_pd_init(struct blkcg_gq *blkg)
int rw;
/*
- * If sane_hierarchy is enabled, we switch to properly hierarchical
+ * If on the default hierarchy, we switch to properly hierarchical
* behavior where limits on a given throtl_grp are applied to the
* whole subtree rather than just the group itself. e.g. If 16M
* read_bps limit is set on the root group, the whole system can't
* exceed 16M for the device.
*
- * If sane_hierarchy is not enabled, the broken flat hierarchy
+ * If not on the default hierarchy, the broken flat hierarchy
* behavior is retained where all throtl_grps are treated as if
* they're all separate root groups right below throtl_data.
* Limits of a group don't interact with limits of other groups
@@ -426,7 +426,7 @@ static void throtl_pd_init(struct blkcg_gq *blkg)
*/
parent_sq = &td->service_queue;
- if (cgroup_sane_behavior(blkg->blkcg->css.cgroup) && blkg->parent)
+ if (cgroup_on_dfl(blkg->blkcg->css.cgroup) && blkg->parent)
parent_sq = &blkg_to_tg(blkg->parent)->service_queue;
throtl_service_queue_init(&tg->service_queue, parent_sq);
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index c4901c19668bd3c272b5cd7b43ec9c3a5cbe4a30..7bb274487c896b21d5fbc59da1c581f564e4dec5 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -256,68 +256,7 @@ struct cgroup {
/* cgroup_root->flags */
enum {
- /*
- * Unfortunately, cgroup core and various controllers are riddled
- * with idiosyncrasies and pointless options. The following flag,
- * when set, will force sane behavior - some options are forced on,
- * others are disallowed, and some controllers will change their
- * hierarchical or other behaviors.
- *
- * The set of behaviors affected by this flag are still being
- * determined and developed and the mount option for this flag is
- * prefixed with __DEVEL__. The prefix will be dropped once we
- * reach the point where all behaviors are compatible with the
- * planned unified hierarchy, which will automatically turn on this
- * flag.
- *
- * The followings are the behaviors currently affected this flag.
- *
- * - Mount options "noprefix", "xattr", "clone_children",
- * "release_agent" and "name" are disallowed.
- *
- * - When mounting an existing superblock, mount options should
- * match.
- *
- * - Remount is disallowed.
- *
- * - rename(2) is disallowed.
- *
- * - "tasks" is removed. Everything should be at process
- * granularity. Use "cgroup.procs" instead.
- *
- * - "cgroup.procs" is not sorted. pids will be unique unless they
- * got recycled inbetween reads.
- *
- * - "release_agent" and "notify_on_release" are removed.
- * Replacement notification mechanism will be implemented.
- *
- * - "cgroup.clone_children" is removed.
- *
- * - "cgroup.subtree_populated" is available. Its value is 0 if
- * the cgroup and its descendants contain no task; otherwise, 1.
- * The file also generates kernfs notification which can be
- * monitored through poll and [di]notify when the value of the
- * file changes.
- *
- * - If mount is requested with sane_behavior but without any
- * subsystem, the default unified hierarchy is mounted.
- *
- * - cpuset: tasks will be kept in empty cpusets when hotplug happens
- * and take masks of ancestors with non-empty cpus/mems, instead of
- * being moved to an ancestor.
- *
- * - cpuset: a task can be moved into an empty cpuset, and again it
- * takes masks of ancestors.
- *
- * - memcg: use_hierarchy is on by default and the cgroup file for
- * the flag is not created.
- *
- * - blkcg: blk-throttle becomes properly hierarchical.
- *
- * - debug: disallowed on the default hierarchy.
- */
- CGRP_ROOT_SANE_BEHAVIOR = (1 << 0),
-
+ CGRP_ROOT_SANE_BEHAVIOR = (1 << 0), /* __DEVEL__sane_behavior specified */
CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */
CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */
};
@@ -531,20 +470,64 @@ struct cftype {
extern struct cgroup_root cgrp_dfl_root;
extern struct css_set init_css_set;
+/**
+ * cgroup_on_dfl - test whether a cgroup is on the default hierarchy
+ * @cgrp: the cgroup of interest
+ *
+ * The default hierarchy is the v2 interface of cgroup and this function
+ * can be used to test whether a cgroup is on the default hierarchy for
+ * cases where a subsystem should behave differnetly depending on the
+ * interface version.
+ *
+ * The set of behaviors which change on the default hierarchy are still
+ * being determined and the mount option is prefixed with __DEVEL__.
+ *
+ * List of changed behaviors:
+ *
+ * - Mount options "noprefix", "xattr", "clone_children", "release_agent"
+ * and "name" are disallowed.
+ *
+ * - When mounting an existing superblock, mount options should match.
+ *
+ * - Remount is disallowed.
+ *
+ * - rename(2) is disallowed.
+ *
+ * - "tasks" is removed. Everything should be at process granularity. Use
+ * "cgroup.procs" instead.
+ *
+ * - "cgroup.procs" is not sorted. pids will be unique unless they got
+ * recycled inbetween reads.
+ *
+ * - "release_agent" and "notify_on_release" are removed. Replacement
+ * notification mechanism will be implemented.
+ *
+ * - "cgroup.clone_children" is removed.
+ *
+ * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup
+ * and its descendants contain no task; otherwise, 1. The file also
+ * generates kernfs notification which can be monitored through poll and
+ * [di]notify when the value of the file changes.
+ *
+ * - cpuset: tasks will be kept in empty cpusets when hotplug happens and
+ * take masks of ancestors with non-empty cpus/mems, instead of being
+ * moved to an ancestor.
+ *
+ * - cpuset: a task can be moved into an empty cpuset, and again it takes
+ * masks of ancestors.
+ *
+ * - memcg: use_hierarchy is on by default and the cgroup file for the flag
+ * is not created.
+ *
+ * - blkcg: blk-throttle becomes properly hierarchical.
+ *
+ * - debug: disallowed on the default hierarchy.
+ */
static inline bool cgroup_on_dfl(const struct cgroup *cgrp)
{
return cgrp->root == &cgrp_dfl_root;
}
-/*
- * See the comment above CGRP_ROOT_SANE_BEHAVIOR for details. This
- * function can be called as long as @cgrp is accessible.
- */
-static inline bool cgroup_sane_behavior(const struct cgroup *cgrp)
-{
- return cgrp->root->flags & CGRP_ROOT_SANE_BEHAVIOR;
-}
-
/* no synchronization, the result can only be used as a hint */
static inline bool cgroup_has_tasks(struct cgroup *cgrp)
{
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 0ea54af6b1333a21b3a03047af60525649f67e97..fb07c6d43aff968c385b8ea8f4e077769937314e 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1470,8 +1470,8 @@ static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
struct cgroup_sb_opts opts;
unsigned int added_mask, removed_mask;
- if (root->flags & CGRP_ROOT_SANE_BEHAVIOR) {
- pr_err("sane_behavior: remount is not allowed\n");
+ if (root == &cgrp_dfl_root) {
+ pr_err("remount is not allowed\n");
return -EINVAL;
}
@@ -2943,9 +2943,9 @@ static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
/*
* This isn't a proper migration and its usefulness is very
- * limited. Disallow if sane_behavior.
+ * limited. Disallow on the default hierarchy.
*/
- if (cgroup_sane_behavior(cgrp))
+ if (cgroup_on_dfl(cgrp))
return -EPERM;
/*
@@ -3031,7 +3031,7 @@ static int cgroup_addrm_files(struct cgroup *cgrp, struct cftype cfts[],
/* does cft->flags tell us to skip this file on @cgrp? */
if ((cft->flags & CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp))
continue;
- if ((cft->flags & CFTYPE_INSANE) && cgroup_sane_behavior(cgrp))
+ if ((cft->flags & CFTYPE_INSANE) && cgroup_on_dfl(cgrp))
continue;
if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgroup_parent(cgrp))
continue;
@@ -3764,8 +3764,9 @@ after:
*
* All this extra complexity was caused by the original implementation
* committing to an entirely unnecessary property. In the long term, we
- * want to do away with it. Explicitly scramble sort order if
- * sane_behavior so that no such expectation exists in the new interface.
+ * want to do away with it. Explicitly scramble sort order if on the
+ * default hierarchy so that no such expectation exists in the new
+ * interface.
*
* Scrambling is done by swapping every two consecutive bits, which is
* non-identity one-to-one mapping which disturbs sort order sufficiently.
@@ -3780,7 +3781,7 @@ static pid_t pid_fry(pid_t pid)
static pid_t cgroup_pid_fry(struct cgroup *cgrp, pid_t pid)
{
- if (cgroup_sane_behavior(cgrp))
+ if (cgroup_on_dfl(cgrp))
return pid_fry(pid);
else
return pid;
@@ -3883,7 +3884,7 @@ static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
css_task_iter_end(&it);
length = n;
/* now sort & (if procs) strip out duplicates */
- if (cgroup_sane_behavior(cgrp))
+ if (cgroup_on_dfl(cgrp))
sort(array, length, sizeof(pid_t), fried_cmppid, NULL);
else
sort(array, length, sizeof(pid_t), cmppid, NULL);
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index f6b33c6962243ee54c955df76f77becf01a1f057..f9d4807c869f0f8fabdca1480ed3a4255cfa0e5c 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1383,12 +1383,9 @@ static int cpuset_can_attach(struct cgroup_subsys_state *css,
mutex_lock(&cpuset_mutex);
- /*
- * We allow to move tasks into an empty cpuset if sane_behavior
- * flag is set.
- */
+ /* allow moving tasks into an empty cpuset if on default hierarchy */
ret = -ENOSPC;
- if (!cgroup_sane_behavior(css->cgroup) &&
+ if (!cgroup_on_dfl(css->cgroup) &&
(cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)))
goto out_unlock;
@@ -2030,7 +2027,7 @@ static void cpuset_hotplug_update_tasks(struct cpuset *cs)
static cpumask_t off_cpus;
static nodemask_t off_mems;
bool is_empty;
- bool sane = cgroup_sane_behavior(cs->css.cgroup);
+ bool on_dfl = cgroup_on_dfl(cs->css.cgroup);
retry:
wait_event(cpuset_attach_wq, cs->attach_in_progress == 0);
@@ -2054,12 +2051,12 @@ retry:
mutex_unlock(&callback_mutex);
/*
- * If sane_behavior flag is set, we need to update tasks' cpumask
- * for empty cpuset to take on ancestor's cpumask. Otherwise, don't
- * call update_tasks_cpumask() if the cpuset becomes empty, as
- * the tasks in it will be migrated to an ancestor.
+ * If on_dfl, we need to update tasks' cpumask for empty cpuset to
+ * take on ancestor's cpumask. Otherwise, don't call
+ * update_tasks_cpumask() if the cpuset becomes empty, as the tasks
+ * in it will be migrated to an ancestor.
*/
- if ((sane && cpumask_empty(cs->cpus_allowed)) ||
+ if ((on_dfl && cpumask_empty(cs->cpus_allowed)) ||
(!cpumask_empty(&off_cpus) && !cpumask_empty(cs->cpus_allowed)))
update_tasks_cpumask(cs);
@@ -2068,12 +2065,12 @@ retry:
mutex_unlock(&callback_mutex);
/*
- * If sane_behavior flag is set, we need to update tasks' nodemask
- * for empty cpuset to take on ancestor's nodemask. Otherwise, don't
- * call update_tasks_nodemask() if the cpuset becomes empty, as
- * the tasks in it will be migratd to an ancestor.
+ * If on_dfl, we need to update tasks' nodemask for empty cpuset to
+ * take on ancestor's nodemask. Otherwise, don't call
+ * update_tasks_nodemask() if the cpuset becomes empty, as the
+ * tasks in it will be migratd to an ancestor.
*/
- if ((sane && nodes_empty(cs->mems_allowed)) ||
+ if ((on_dfl && nodes_empty(cs->mems_allowed)) ||
(!nodes_empty(off_mems) && !nodes_empty(cs->mems_allowed)))
update_tasks_nodemask(cs);
@@ -2083,13 +2080,13 @@ retry:
mutex_unlock(&cpuset_mutex);
/*
- * If sane_behavior flag is set, we'll keep tasks in empty cpusets.
+ * If on_dfl, we'll keep tasks in empty cpusets.
*
* Otherwise move tasks to the nearest ancestor with execution
* resources. This is full cgroup operation which will
* also call back into cpuset. Should be done outside any lock.
*/
- if (!sane && is_empty)
+ if (!on_dfl && is_empty)
remove_tasks_in_empty_cpuset(cs);
}
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index db536e90c8ee852b54406051b3b58b525d8a51ce..a2a4bd69a7ae8e3c1fb5774d77eaa1464d97958e 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -7024,16 +7024,17 @@ static void mem_cgroup_move_task(struct cgroup_subsys_state *css,
/*
* Cgroup retains root cgroups across [un]mount cycles making it necessary
- * to verify sane_behavior flag on each mount attempt.
+ * to verify whether we're attached to the default hierarchy on each mount
+ * attempt.
*/
static void mem_cgroup_bind(struct cgroup_subsys_state *root_css)
{
/*
- * use_hierarchy is forced with sane_behavior. cgroup core
+ * use_hierarchy is forced on the default hierarchy. cgroup core
* guarantees that @root doesn't have any children, so turning it
* on for the root memcg is enough.
*/
- if (cgroup_sane_behavior(root_css->cgroup))
+ if (cgroup_on_dfl(root_css->cgroup))
mem_cgroup_from_css(root_css)->use_hierarchy = true;
}