cgroup: remove sane_behavior support on non-default hierarchies (aa6ec29b) · Commits · 戴 / test

block/blk-throttle.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -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);

include/linux/cgroup.h

+54 −71

Original line number	Diff line number	Diff line
		@@ -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)
		{

kernel/cgroup.c

+10 −9

Original line number	Diff line number	Diff line
		@@ -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);

kernel/cpuset.c

+15 −18

Original line number	Diff line number	Diff line
		@@ -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);
		}

mm/memcontrol.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -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;
		}

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