Merge branch 'for-3.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull cgroup updates from Tejun Heo:
"cgroup file type addition / removal is updated so that file types are
added and removed instead of individual files so that dynamic file
type addition / removal can be implemented by cgroup and used by
controllers. blkio controller changes which will come through block
tree are dependent on this. Other changes include res_counter cleanup
and disallowing kthread / PF_THREAD_BOUND threads to be attached to
non-root cgroups.

There's a reported bug with the file type addition / removal handling
which can lead to oops on cgroup umount. The issue is being looked
into. It shouldn't cause problems for most setups and isn't a
security concern."

Fix up trivial conflict in Documentation/feature-removal-schedule.txt

* 'for-3.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (21 commits)
res_counter: Account max_usage when calling res_counter_charge_nofail()
res_counter: Merge res_counter_charge and res_counter_charge_nofail
cgroups: disallow attaching kthreadd or PF_THREAD_BOUND threads
cgroup: remove cgroup_subsys->populate()
cgroup: get rid of populate for memcg
cgroup: pass struct mem_cgroup instead of struct cgroup to socket memcg
cgroup: make css->refcnt clearing on cgroup removal optional
cgroup: use negative bias on css->refcnt to block css_tryget()
cgroup: implement cgroup_rm_cftypes()
cgroup: introduce struct cfent
cgroup: relocate __d_cgrp() and __d_cft()
cgroup: remove cgroup_add_file[s]()
cgroup: convert memcg controller to the new cftype interface
memcg: always create memsw files if CONFIG_CGROUP_MEM_RES_CTLR_SWAP
cgroup: convert all non-memcg controllers to the new cftype interface
cgroup: relocate cftype and cgroup_subsys definitions in controllers
cgroup: merge cft_release_agent cftype array into the base files array
cgroup: implement cgroup_add_cftypes() and friends
cgroup: build list of all cgroups under a given cgroupfs_root
cgroup: move cgroup_clear_directory() call out of cgroup_populate_dir()
...

Documentation/cgroups/resource_counter.txt

···
 	where the charging failed.
 
  d. int res_counter_charge_locked
-			(struct res_counter *rc, unsigned long val)
+			(struct res_counter *rc, unsigned long val, bool force)
 
 	The same as res_counter_charge(), but it must not acquire/release the
 	res_counter->lock internally (it must be called with res_counter->lock
-	held).
+	held). The force parameter indicates whether we can bypass the limit.
 
  e. void res_counter_uncharge[_locked]
 			(struct res_counter *rc, unsigned long val)

Documentation/feature-removal-schedule.txt

···
 	There are newer controls (V4L2_CID_PAN*, V4L2_CID_TILT*) that provide
 	similar	functionality.
 Who:	Sylwester Nawrocki <[e-mail]>
+
+----------------------------
+
+What:	cgroup option updates via remount
+When:	March 2013
+Why:	Remount currently allows changing bound subsystems and
+	release_agent.  Rebinding is hardly useful as it only works
+	when the hierarchy is empty and release_agent itself should be
+	replaced with conventional fsnotify.
+
+----------------------------

block/blk-cgroup.c

···
 struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT };
 EXPORT_SYMBOL_GPL(blkio_root_cgroup);
 
-static struct cgroup_subsys_state *blkiocg_create(struct cgroup *);
-static int blkiocg_can_attach(struct cgroup *, struct cgroup_taskset *);
-static void blkiocg_attach(struct cgroup *, struct cgroup_taskset *);
-static void blkiocg_destroy(struct cgroup *);
-static int blkiocg_populate(struct cgroup_subsys *, struct cgroup *);
-
 /* for encoding cft->private value on file */
 #define BLKIOFILE_PRIVATE(x, val)	(((x) << 16) | (val))
 /* What policy owns the file, proportional or throttle */
 #define BLKIOFILE_POLICY(val)		(((val) >> 16) & 0xffff)
 #define BLKIOFILE_ATTR(val)		((val) & 0xffff)
-
-struct cgroup_subsys blkio_subsys = {
-	.name = "blkio",
-	.create = blkiocg_create,
-	.can_attach = blkiocg_can_attach,
-	.attach = blkiocg_attach,
-	.destroy = blkiocg_destroy,
-	.populate = blkiocg_populate,
-#ifdef CONFIG_BLK_CGROUP
-	/* note: blkio_subsys_id is otherwise defined in blk-cgroup.h */
-	.subsys_id = blkio_subsys_id,
-#endif
-	.use_id = 1,
-	.module = THIS_MODULE,
-};
-EXPORT_SYMBOL_GPL(blkio_subsys);
 
 static inline void blkio_policy_insert_node(struct blkio_cgroup *blkcg,
 					    struct blkio_policy_node *pn)
···
 		.read_map = blkiocg_file_read_map,
 	},
 #endif
+	{ }	/* terminate */
 };
-
-static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
-{
-	return cgroup_add_files(cgroup, subsys, blkio_files,
-				ARRAY_SIZE(blkio_files));
-}
 
 static void blkiocg_destroy(struct cgroup *cgroup)
 {
···
 		}
 	}
 }
+
+struct cgroup_subsys blkio_subsys = {
+	.name = "blkio",
+	.create = blkiocg_create,
+	.can_attach = blkiocg_can_attach,
+	.attach = blkiocg_attach,
+	.destroy = blkiocg_destroy,
+#ifdef CONFIG_BLK_CGROUP
+	/* note: blkio_subsys_id is otherwise defined in blk-cgroup.h */
+	.subsys_id = blkio_subsys_id,
+#endif
+	.base_cftypes = blkio_files,
+	.use_id = 1,
+	.module = THIS_MODULE,
+};
+EXPORT_SYMBOL_GPL(blkio_subsys);
 
 void blkio_policy_register(struct blkio_policy_type *blkiop)
 {

include/linux/cgroup.h

···
 #include <linux/prio_heap.h>
 #include <linux/rwsem.h>
 #include <linux/idr.h>
+#include <linux/workqueue.h>
 
 #ifdef CONFIG_CGROUPS
 
···
 	unsigned long flags;
 	/* ID for this css, if possible */
 	struct css_id __rcu *id;
+
+	/* Used to put @cgroup->dentry on the last css_put() */
+	struct work_struct dput_work;
 };
 
 /* bits in struct cgroup_subsys_state flags field */
 enum {
 	CSS_ROOT, /* This CSS is the root of the subsystem */
 	CSS_REMOVED, /* This CSS is dead */
+	CSS_CLEAR_CSS_REFS,		/* @ss->__DEPRECATED_clear_css_refs */
 };
 
 /* Caller must verify that the css is not for root cgroup */
···
  * the css has been destroyed.
  */
 
+extern bool __css_tryget(struct cgroup_subsys_state *css);
 static inline bool css_tryget(struct cgroup_subsys_state *css)
 {
 	if (test_bit(CSS_ROOT, &css->flags))
 		return true;
-	while (!atomic_inc_not_zero(&css->refcnt)) {
-		if (test_bit(CSS_REMOVED, &css->flags))
-			return false;
-		cpu_relax();
-	}
-	return true;
+	return __css_tryget(css);
 }
 
 /*
···
  * css_get() or css_tryget()
  */
 
-extern void __css_put(struct cgroup_subsys_state *css, int count);
+extern void __css_put(struct cgroup_subsys_state *css);
 static inline void css_put(struct cgroup_subsys_state *css)
 {
 	if (!test_bit(CSS_ROOT, &css->flags))
-		__css_put(css, 1);
+		__css_put(css);
 }
 
 /* bits in struct cgroup flags field */
···
 	 */
 	struct list_head sibling;	/* my parent's children */
 	struct list_head children;	/* my children */
+	struct list_head files;		/* my files */
 
 	struct cgroup *parent;		/* my parent */
 	struct dentry __rcu *dentry;	/* cgroup fs entry, RCU protected */
···
 	 * tasks in this cgroup. Protected by css_set_lock
 	 */
 	struct list_head css_sets;
+
+	struct list_head allcg_node;	/* cgroupfs_root->allcg_list */
+	struct list_head cft_q_node;	/* used during cftype add/rm */
 
 	/*
 	 * Linked list running through all cgroups that can
···
  *	- the 'cftype' of the file is file->f_dentry->d_fsdata
  */
 
-#define MAX_CFTYPE_NAME 64
+/* cftype->flags */
+#define CFTYPE_ONLY_ON_ROOT	(1U << 0)	/* only create on root cg */
+#define CFTYPE_NOT_ON_ROOT	(1U << 1)	/* don't create onp root cg */
+
+#define MAX_CFTYPE_NAME		64
+
 struct cftype {
 	/*
 	 * By convention, the name should begin with the name of the
-	 * subsystem, followed by a period
+	 * subsystem, followed by a period.  Zero length string indicates
+	 * end of cftype array.
 	 */
 	char name[MAX_CFTYPE_NAME];
 	int private;
···
 	 * be passed to write_string; defaults to 64
 	 */
 	size_t max_write_len;
+
+	/* CFTYPE_* flags */
+	unsigned int flags;
 
 	int (*open)(struct inode *inode, struct file *file);
 	ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft,
···
 			struct eventfd_ctx *eventfd);
 };
 
+/*
+ * cftype_sets describe cftypes belonging to a subsystem and are chained at
+ * cgroup_subsys->cftsets.  Each cftset points to an array of cftypes
+ * terminated by zero length name.
+ */
+struct cftype_set {
+	struct list_head		node;	/* chained at subsys->cftsets */
+	const struct cftype		*cfts;
+};
+
 struct cgroup_scanner {
 	struct cgroup *cg;
 	int (*test_task)(struct task_struct *p, struct cgroup_scanner *scan);
···
 	void *data;
 };
 
-/*
- * Add a new file to the given cgroup directory. Should only be
- * called by subsystems from within a populate() method
- */
-int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,
-		       const struct cftype *cft);
-
-/*
- * Add a set of new files to the given cgroup directory. Should
- * only be called by subsystems from within a populate() method
- */
-int cgroup_add_files(struct cgroup *cgrp,
-			struct cgroup_subsys *subsys,
-			const struct cftype cft[],
-			int count);
+int cgroup_add_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts);
+int cgroup_rm_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts);
 
 int cgroup_is_removed(const struct cgroup *cgrp);
 
···
 	void (*fork)(struct task_struct *task);
 	void (*exit)(struct cgroup *cgrp, struct cgroup *old_cgrp,
 		     struct task_struct *task);
-	int (*populate)(struct cgroup_subsys *ss, struct cgroup *cgrp);
 	void (*post_clone)(struct cgroup *cgrp);
 	void (*bind)(struct cgroup *root);
 
···
 	 * (not available in early_init time.)
 	 */
 	bool use_id;
+
+	/*
+	 * If %true, cgroup removal will try to clear css refs by retrying
+	 * ss->pre_destroy() until there's no css ref left.  This behavior
+	 * is strictly for backward compatibility and will be removed as
+	 * soon as the current user (memcg) is updated.
+	 *
+	 * If %false, ss->pre_destroy() can't fail and cgroup removal won't
+	 * wait for css refs to drop to zero before proceeding.
+	 */
+	bool __DEPRECATED_clear_css_refs;
+
 #define MAX_CGROUP_TYPE_NAMELEN 32
 	const char *name;
 
···
 	/* used when use_id == true */
 	struct idr idr;
 	spinlock_t id_lock;
+
+	/* list of cftype_sets */
+	struct list_head cftsets;
+
+	/* base cftypes, automatically [de]registered with subsys itself */
+	struct cftype *base_cftypes;
+	struct cftype_set base_cftset;
 
 	/* should be defined only by modular subsystems */
 	struct module *module;

include/linux/res_counter.h

···
  */
 
 int __must_check res_counter_charge_locked(struct res_counter *counter,
-		unsigned long val);
+					   unsigned long val, bool force);
 int __must_check res_counter_charge(struct res_counter *counter,
 		unsigned long val, struct res_counter **limit_fail_at);
 int __must_check res_counter_charge_nofail(struct res_counter *counter,

include/net/sock.h

···
 struct cgroup;
 struct cgroup_subsys;
 #ifdef CONFIG_NET
-int mem_cgroup_sockets_init(struct cgroup *cgrp, struct cgroup_subsys *ss);
-void mem_cgroup_sockets_destroy(struct cgroup *cgrp);
+int mem_cgroup_sockets_init(struct mem_cgroup *memcg, struct cgroup_subsys *ss);
+void mem_cgroup_sockets_destroy(struct mem_cgroup *memcg);
 #else
 static inline
-int mem_cgroup_sockets_init(struct cgroup *cgrp, struct cgroup_subsys *ss)
+int mem_cgroup_sockets_init(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
 {
 	return 0;
 }
 static inline
-void mem_cgroup_sockets_destroy(struct cgroup *cgrp)
+void mem_cgroup_sockets_destroy(struct mem_cgroup *memcg)
 {
 }
 #endif
···
 	 * This function has to setup any files the protocol want to
 	 * appear in the kmem cgroup filesystem.
 	 */
-	int			(*init_cgroup)(struct cgroup *cgrp,
+	int			(*init_cgroup)(struct mem_cgroup *memcg,
 					       struct cgroup_subsys *ss);
-	void			(*destroy_cgroup)(struct cgroup *cgrp);
+	void			(*destroy_cgroup)(struct mem_cgroup *memcg);
 	struct cg_proto		*(*proto_cgroup)(struct mem_cgroup *memcg);
 #endif
 };

include/net/tcp_memcontrol.h

···
 };
 
 struct cg_proto *tcp_proto_cgroup(struct mem_cgroup *memcg);
-int tcp_init_cgroup(struct cgroup *cgrp, struct cgroup_subsys *ss);
-void tcp_destroy_cgroup(struct cgroup *cgrp);
+int tcp_init_cgroup(struct mem_cgroup *memcg, struct cgroup_subsys *ss);
+void tcp_destroy_cgroup(struct mem_cgroup *memcg);
 unsigned long long tcp_max_memory(const struct mem_cgroup *memcg);
 void tcp_prot_mem(struct mem_cgroup *memcg, long val, int idx);
 #endif /* _TCP_MEMCG_H */

kernel/cgroup.c

···
 #include <linux/eventfd.h>
 #include <linux/poll.h>
 #include <linux/flex_array.h> /* used in cgroup_attach_proc */
+#include <linux/kthread.h>
 
 #include <linux/atomic.h>
+
+/* css deactivation bias, makes css->refcnt negative to deny new trygets */
+#define CSS_DEACT_BIAS		INT_MIN
 
 /*
  * cgroup_mutex is the master lock.  Any modification to cgroup or its
···
 	/* A list running through the active hierarchies */
 	struct list_head root_list;
 
+	/* All cgroups on this root, cgroup_mutex protected */
+	struct list_head allcg_list;
+
 	/* Hierarchy-specific flags */
 	unsigned long flags;
 
···
  * single cgroup, and all tasks are part of that cgroup.
  */
 static struct cgroupfs_root rootnode;
+
+/*
+ * cgroupfs file entry, pointed to from leaf dentry->d_fsdata.
+ */
+struct cfent {
+	struct list_head		node;
+	struct dentry			*dentry;
+	struct cftype			*type;
+};
 
 /*
  * CSS ID -- ID per subsys's Cgroup Subsys State(CSS). used only when
···
 
 EXPORT_SYMBOL_GPL(cgroup_lock_is_held);
 
+/* the current nr of refs, always >= 0 whether @css is deactivated or not */
+static int css_refcnt(struct cgroup_subsys_state *css)
+{
+	int v = atomic_read(&css->refcnt);
+
+	return v >= 0 ? v : v - CSS_DEACT_BIAS;
+}
+
 /* convenient tests for these bits */
 inline int cgroup_is_removed(const struct cgroup *cgrp)
 {
···
 /* for_each_active_root() allows you to iterate across the active hierarchies */
 #define for_each_active_root(_root) \
 list_for_each_entry(_root, &roots, root_list)
+
+static inline struct cgroup *__d_cgrp(struct dentry *dentry)
+{
+	return dentry->d_fsdata;
+}
+
+static inline struct cfent *__d_cfe(struct dentry *dentry)
+{
+	return dentry->d_fsdata;
+}
+
+static inline struct cftype *__d_cft(struct dentry *dentry)
+{
+	return __d_cfe(dentry)->type;
+}
 
 /* the list of cgroups eligible for automatic release. Protected by
  * release_list_lock */
···
 	struct cgroup_subsys *ss;
 	int ret = 0;
 
-	for_each_subsys(cgrp->root, ss)
-		if (ss->pre_destroy) {
-			ret = ss->pre_destroy(cgrp);
-			if (ret)
-				break;
+	for_each_subsys(cgrp->root, ss) {
+		if (!ss->pre_destroy)
+			continue;
+
+		ret = ss->pre_destroy(cgrp);
+		if (ret) {
+			/* ->pre_destroy() failure is being deprecated */
+			WARN_ON_ONCE(!ss->__DEPRECATED_clear_css_refs);
+			break;
 		}
+	}
 
 	return ret;
 }
···
 		BUG_ON(!list_empty(&cgrp->pidlists));
 
 		kfree_rcu(cgrp, rcu_head);
+	} else {
+		struct cfent *cfe = __d_cfe(dentry);
+		struct cgroup *cgrp = dentry->d_parent->d_fsdata;
+
+		WARN_ONCE(!list_empty(&cfe->node) &&
+			  cgrp != &cgrp->root->top_cgroup,
+			  "cfe still linked for %s\n", cfe->type->name);
+		kfree(cfe);
 	}
 	iput(inode);
 }
···
 	dput(parent);
 }
 
-static void cgroup_clear_directory(struct dentry *dentry)
+static int cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
 {
-	struct list_head *node;
+	struct cfent *cfe;
 
-	BUG_ON(!mutex_is_locked(&dentry->d_inode->i_mutex));
-	spin_lock(&dentry->d_lock);
-	node = dentry->d_subdirs.next;
-	while (node != &dentry->d_subdirs) {
-		struct dentry *d = list_entry(node, struct dentry, d_u.d_child);
+	lockdep_assert_held(&cgrp->dentry->d_inode->i_mutex);
+	lockdep_assert_held(&cgroup_mutex);
 
-		spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED);
-		list_del_init(node);
-		if (d->d_inode) {
-			/* This should never be called on a cgroup
-			 * directory with child cgroups */
-			BUG_ON(d->d_inode->i_mode & S_IFDIR);
-			dget_dlock(d);
-			spin_unlock(&d->d_lock);
-			spin_unlock(&dentry->d_lock);
-			d_delete(d);
-			simple_unlink(dentry->d_inode, d);
-			dput(d);
-			spin_lock(&dentry->d_lock);
-		} else
-			spin_unlock(&d->d_lock);
-		node = dentry->d_subdirs.next;
+	list_for_each_entry(cfe, &cgrp->files, node) {
+		struct dentry *d = cfe->dentry;
+
+		if (cft && cfe->type != cft)
+			continue;
+
+		dget(d);
+		d_delete(d);
+		simple_unlink(d->d_inode, d);
+		list_del_init(&cfe->node);
+		dput(d);
+
+		return 0;
 	}
-	spin_unlock(&dentry->d_lock);
+	return -ENOENT;
+}
+
+static void cgroup_clear_directory(struct dentry *dir)
+{
+	struct cgroup *cgrp = __d_cgrp(dir);
+
+	while (!list_empty(&cgrp->files))
+		cgroup_rm_file(cgrp, NULL);
 }
 
 /*
···
 	if (ret)
 		goto out_unlock;
 
+	/* See feature-removal-schedule.txt */
+	if (opts.subsys_bits != root->actual_subsys_bits || opts.release_agent)
+		pr_warning("cgroup: option changes via remount are deprecated (pid=%d comm=%s)\n",
+			   task_tgid_nr(current), current->comm);
+
 	/* Don't allow flags or name to change at remount */
 	if (opts.flags != root->flags ||
 	    (opts.name && strcmp(opts.name, root->name))) {
···
 		goto out_unlock;
 	}
 
-	/* (re)populate subsystem files */
+	/* clear out any existing files and repopulate subsystem files */
+	cgroup_clear_directory(cgrp->dentry);
 	cgroup_populate_dir(cgrp);
 
 	if (opts.release_agent)
···
 {
 	INIT_LIST_HEAD(&cgrp->sibling);
 	INIT_LIST_HEAD(&cgrp->children);
+	INIT_LIST_HEAD(&cgrp->files);
 	INIT_LIST_HEAD(&cgrp->css_sets);
 	INIT_LIST_HEAD(&cgrp->release_list);
 	INIT_LIST_HEAD(&cgrp->pidlists);
···
 static void init_cgroup_root(struct cgroupfs_root *root)
 {
 	struct cgroup *cgrp = &root->top_cgroup;
+
 	INIT_LIST_HEAD(&root->subsys_list);
 	INIT_LIST_HEAD(&root->root_list);
+	INIT_LIST_HEAD(&root->allcg_list);
 	root->number_of_cgroups = 1;
 	cgrp->root = root;
 	cgrp->top_cgroup = cgrp;
+	list_add_tail(&cgrp->allcg_node, &root->allcg_list);
 	init_cgroup_housekeeping(cgrp);
 }
 
···
 };
 
 static struct kobject *cgroup_kobj;
-
-static inline struct cgroup *__d_cgrp(struct dentry *dentry)
-{
-	return dentry->d_fsdata;
-}
-
-static inline struct cftype *__d_cft(struct dentry *dentry)
-{
-	return dentry->d_fsdata;
-}
 
 /**
  * cgroup_path - generate the path of a cgroup
···
 
 	if (threadgroup)
 		tsk = tsk->group_leader;
+
+	/*
+	 * Workqueue threads may acquire PF_THREAD_BOUND and become
+	 * trapped in a cpuset, or RT worker may be born in a cgroup
+	 * with no rt_runtime allocated.  Just say no.
+	 */
+	if (tsk == kthreadd_task || (tsk->flags & PF_THREAD_BOUND)) {
+		ret = -EINVAL;
+		rcu_read_unlock();
+		goto out_unlock_cgroup;
+	}
+
 	get_task_struct(tsk);
 	rcu_read_unlock();
 
···
 	return mode;
 }
 
-int cgroup_add_file(struct cgroup *cgrp,
-		       struct cgroup_subsys *subsys,
-		       const struct cftype *cft)
+static int cgroup_add_file(struct cgroup *cgrp, struct cgroup_subsys *subsys,
+			   const struct cftype *cft)
 {
 	struct dentry *dir = cgrp->dentry;
+	struct cgroup *parent = __d_cgrp(dir);
 	struct dentry *dentry;
+	struct cfent *cfe;
 	int error;
 	umode_t mode;
-
 	char name[MAX_CGROUP_TYPE_NAMELEN + MAX_CFTYPE_NAME + 2] = { 0 };
+
+	/* does @cft->flags tell us to skip creation on @cgrp? */
+	if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgrp->parent)
+		return 0;
+	if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgrp->parent)
+		return 0;
+
 	if (subsys && !test_bit(ROOT_NOPREFIX, &cgrp->root->flags)) {
 		strcpy(name, subsys->name);
 		strcat(name, ".");
 	}
 	strcat(name, cft->name);
+
 	BUG_ON(!mutex_is_locked(&dir->d_inode->i_mutex));
+
+	cfe = kzalloc(sizeof(*cfe), GFP_KERNEL);
+	if (!cfe)
+		return -ENOMEM;
+
 	dentry = lookup_one_len(name, dir, strlen(name));
-	if (!IS_ERR(dentry)) {
-		mode = cgroup_file_mode(cft);
-		error = cgroup_create_file(dentry, mode | S_IFREG,
-						cgrp->root->sb);
-		if (!error)
-			dentry->d_fsdata = (void *)cft;
-		dput(dentry);
-	} else
+	if (IS_ERR(dentry)) {
 		error = PTR_ERR(dentry);
+		goto out;
+	}
+
+	mode = cgroup_file_mode(cft);
+	error = cgroup_create_file(dentry, mode | S_IFREG, cgrp->root->sb);
+	if (!error) {
+		cfe->type = (void *)cft;
+		cfe->dentry = dentry;
+		dentry->d_fsdata = cfe;
+		list_add_tail(&cfe->node, &parent->files);
+		cfe = NULL;
+	}
+	dput(dentry);
+out:
+	kfree(cfe);
 	return error;
 }
-EXPORT_SYMBOL_GPL(cgroup_add_file);
 
-int cgroup_add_files(struct cgroup *cgrp,
-			struct cgroup_subsys *subsys,
-			const struct cftype cft[],
-			int count)
+static int cgroup_addrm_files(struct cgroup *cgrp, struct cgroup_subsys *subsys,
+			      const struct cftype cfts[], bool is_add)
 {
-	int i, err;
-	for (i = 0; i < count; i++) {
-		err = cgroup_add_file(cgrp, subsys, &cft[i]);
-		if (err)
-			return err;
+	const struct cftype *cft;
+	int err, ret = 0;
+
+	for (cft = cfts; cft->name[0] != '\0'; cft++) {
+		if (is_add)
+			err = cgroup_add_file(cgrp, subsys, cft);
+		else
+			err = cgroup_rm_file(cgrp, cft);
+		if (err) {
+			pr_warning("cgroup_addrm_files: failed to %s %s, err=%d\n",
+				   is_add ? "add" : "remove", cft->name, err);
+			ret = err;
+		}
 	}
+	return ret;
+}
+
+static DEFINE_MUTEX(cgroup_cft_mutex);
+
+static void cgroup_cfts_prepare(void)
+	__acquires(&cgroup_cft_mutex) __acquires(&cgroup_mutex)
+{
+	/*
+	 * Thanks to the entanglement with vfs inode locking, we can't walk
+	 * the existing cgroups under cgroup_mutex and create files.
+	 * Instead, we increment reference on all cgroups and build list of
+	 * them using @cgrp->cft_q_node.  Grab cgroup_cft_mutex to ensure
+	 * exclusive access to the field.
+	 */
+	mutex_lock(&cgroup_cft_mutex);
+	mutex_lock(&cgroup_mutex);
+}
+
+static void cgroup_cfts_commit(struct cgroup_subsys *ss,
+			       const struct cftype *cfts, bool is_add)
+	__releases(&cgroup_mutex) __releases(&cgroup_cft_mutex)
+{
+	LIST_HEAD(pending);
+	struct cgroup *cgrp, *n;
+
+	/* %NULL @cfts indicates abort and don't bother if @ss isn't attached */
+	if (cfts && ss->root != &rootnode) {
+		list_for_each_entry(cgrp, &ss->root->allcg_list, allcg_node) {
+			dget(cgrp->dentry);
+			list_add_tail(&cgrp->cft_q_node, &pending);
+		}
+	}
+
+	mutex_unlock(&cgroup_mutex);
+
+	/*
+	 * All new cgroups will see @cfts update on @ss->cftsets.  Add/rm
+	 * files for all cgroups which were created before.
+	 */
+	list_for_each_entry_safe(cgrp, n, &pending, cft_q_node) {
+		struct inode *inode = cgrp->dentry->d_inode;
+
+		mutex_lock(&inode->i_mutex);
+		mutex_lock(&cgroup_mutex);
+		if (!cgroup_is_removed(cgrp))
+			cgroup_addrm_files(cgrp, ss, cfts, is_add);
+		mutex_unlock(&cgroup_mutex);
+		mutex_unlock(&inode->i_mutex);
+
+		list_del_init(&cgrp->cft_q_node);
+		dput(cgrp->dentry);
+	}
+
+	mutex_unlock(&cgroup_cft_mutex);
+}
+
+/**
+ * cgroup_add_cftypes - add an array of cftypes to a subsystem
+ * @ss: target cgroup subsystem
+ * @cfts: zero-length name terminated array of cftypes
+ *
+ * Register @cfts to @ss.  Files described by @cfts are created for all
+ * existing cgroups to which @ss is attached and all future cgroups will
+ * have them too.  This function can be called anytime whether @ss is
+ * attached or not.
+ *
+ * Returns 0 on successful registration, -errno on failure.  Note that this
+ * function currently returns 0 as long as @cfts registration is successful
+ * even if some file creation attempts on existing cgroups fail.
+ */
+int cgroup_add_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts)
+{
+	struct cftype_set *set;
+
+	set = kzalloc(sizeof(*set), GFP_KERNEL);
+	if (!set)
+		return -ENOMEM;
+
+	cgroup_cfts_prepare();
+	set->cfts = cfts;
+	list_add_tail(&set->node, &ss->cftsets);
+	cgroup_cfts_commit(ss, cfts, true);
+
 	return 0;
 }
-EXPORT_SYMBOL_GPL(cgroup_add_files);
+EXPORT_SYMBOL_GPL(cgroup_add_cftypes);
+
+/**
+ * cgroup_rm_cftypes - remove an array of cftypes from a subsystem
+ * @ss: target cgroup subsystem
+ * @cfts: zero-length name terminated array of cftypes
+ *
+ * Unregister @cfts from @ss.  Files described by @cfts are removed from
+ * all existing cgroups to which @ss is attached and all future cgroups
+ * won't have them either.  This function can be called anytime whether @ss
+ * is attached or not.
+ *
+ * Returns 0 on successful unregistration, -ENOENT if @cfts is not
+ * registered with @ss.
+ */
+int cgroup_rm_cftypes(struct cgroup_subsys *ss, const struct cftype *cfts)
+{
+	struct cftype_set *set;
+
+	cgroup_cfts_prepare();
+
+	list_for_each_entry(set, &ss->cftsets, node) {
+		if (set->cfts == cfts) {
+			list_del_init(&set->node);
+			cgroup_cfts_commit(ss, cfts, false);
+			return 0;
+		}
+	}
+
+	cgroup_cfts_commit(ss, NULL, false);
+	return -ENOENT;
+}
 
 /**
  * cgroup_task_count - count the number of tasks in a cgroup.
···
 		.read_u64 = cgroup_clone_children_read,
 		.write_u64 = cgroup_clone_children_write,
 	},
-};
-
-static struct cftype cft_release_agent = {
-	.name = "release_agent",
-	.read_seq_string = cgroup_release_agent_show,
-	.write_string = cgroup_release_agent_write,
-	.max_write_len = PATH_MAX,
+	{
+		.name = "release_agent",
+		.flags = CFTYPE_ONLY_ON_ROOT,
+		.read_seq_string = cgroup_release_agent_show,
+		.write_string = cgroup_release_agent_write,
+		.max_write_len = PATH_MAX,
+	},
+	{ }	/* terminate */
 };
 
 static int cgroup_populate_dir(struct cgroup *cgrp)
···
 	int err;
 	struct cgroup_subsys *ss;
 
-	/* First clear out any existing files */
-	cgroup_clear_directory(cgrp->dentry);
-
-	err = cgroup_add_files(cgrp, NULL, files, ARRAY_SIZE(files));
+	err = cgroup_addrm_files(cgrp, NULL, files, true);
 	if (err < 0)
 		return err;
 
-	if (cgrp == cgrp->top_cgroup) {
-		if ((err = cgroup_add_file(cgrp, NULL, &cft_release_agent)) < 0)
-			return err;
+	/* process cftsets of each subsystem */
+	for_each_subsys(cgrp->root, ss) {
+		struct cftype_set *set;
+
+		list_for_each_entry(set, &ss->cftsets, node)
+			cgroup_addrm_files(cgrp, ss, set->cfts, true);
 	}
 
-	for_each_subsys(cgrp->root, ss) {
-		if (ss->populate && (err = ss->populate(ss, cgrp)) < 0)
-			return err;
-	}
 	/* This cgroup is ready now */
 	for_each_subsys(cgrp->root, ss) {
 		struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
···
 	return 0;
 }
 
+static void css_dput_fn(struct work_struct *work)
+{
+	struct cgroup_subsys_state *css =
+		container_of(work, struct cgroup_subsys_state, dput_work);
+
+	dput(css->cgroup->dentry);
+}
+
 static void init_cgroup_css(struct cgroup_subsys_state *css,
 			       struct cgroup_subsys *ss,
 			       struct cgroup *cgrp)
···
 		set_bit(CSS_ROOT, &css->flags);
 	BUG_ON(cgrp->subsys[ss->subsys_id]);
 	cgrp->subsys[ss->subsys_id] = css;
+
+	/*
+	 * If !clear_css_refs, css holds an extra ref to @cgrp->dentry
+	 * which is put on the last css_put().  dput() requires process
+	 * context, which css_put() may be called without.  @css->dput_work
+	 * will be used to invoke dput() asynchronously from css_put().
+	 */
+	INIT_WORK(&css->dput_work, css_dput_fn);
+	if (ss->__DEPRECATED_clear_css_refs)
+		set_bit(CSS_CLEAR_CSS_REFS, &css->flags);
 }
 
 static void cgroup_lock_hierarchy(struct cgroupfs_root *root)
···
 	if (err < 0)
 		goto err_remove;
 
+	/* If !clear_css_refs, each css holds a ref to the cgroup's dentry */
+	for_each_subsys(root, ss)
+		if (!ss->__DEPRECATED_clear_css_refs)
+			dget(dentry);
+
 	/* The cgroup directory was pre-locked for us */
 	BUG_ON(!mutex_is_locked(&cgrp->dentry->d_inode->i_mutex));
+
+	list_add_tail(&cgrp->allcg_node, &root->allcg_list);
 
 	err = cgroup_populate_dir(cgrp);
 	/* If err < 0, we have a half-filled directory - oh well ;) */
···
 	return cgroup_create(c_parent, dentry, mode | S_IFDIR);
 }
 
+/*
+ * Check the reference count on each subsystem. Since we already
+ * established that there are no tasks in the cgroup, if the css refcount
+ * is also 1, then there should be no outstanding references, so the
+ * subsystem is safe to destroy. We scan across all subsystems rather than
+ * using the per-hierarchy linked list of mounted subsystems since we can
+ * be called via check_for_release() with no synchronization other than
+ * RCU, and the subsystem linked list isn't RCU-safe.
+ */
 static int cgroup_has_css_refs(struct cgroup *cgrp)
 {
-	/* Check the reference count on each subsystem. Since we
-	 * already established that there are no tasks in the
-	 * cgroup, if the css refcount is also 1, then there should
-	 * be no outstanding references, so the subsystem is safe to
-	 * destroy. We scan across all subsystems rather than using
-	 * the per-hierarchy linked list of mounted subsystems since
-	 * we can be called via check_for_release() with no
-	 * synchronization other than RCU, and the subsystem linked
-	 * list isn't RCU-safe */
 	int i;
+
 	/*
 	 * We won't need to lock the subsys array, because the subsystems
 	 * we're concerned about aren't going anywhere since our cgroup root
···
 	for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
 		struct cgroup_subsys *ss = subsys[i];
 		struct cgroup_subsys_state *css;
+
 		/* Skip subsystems not present or not in this hierarchy */
 		if (ss == NULL || ss->root != cgrp->root)
 			continue;
+
 		css = cgrp->subsys[ss->subsys_id];
-		/* When called from check_for_release() it's possible
+		/*
+		 * When called from check_for_release() it's possible
 		 * that by this point the cgroup has been removed
 		 * and the css deleted. But a false-positive doesn't
 		 * matter, since it can only happen if the cgroup
 		 * has been deleted and hence no longer needs the
-		 * release agent to be called anyway. */
-		if (css && (atomic_read(&css->refcnt) > 1))
+		 * release agent to be called anyway.
+		 */
+		if (css && css_refcnt(css) > 1)
 			return 1;
 	}
 	return 0;
···
  * Atomically mark all (or else none) of the cgroup's CSS objects as
  * CSS_REMOVED. Return true on success, or false if the cgroup has
  * busy subsystems. Call with cgroup_mutex held
+ *
+ * Depending on whether a subsys has __DEPRECATED_clear_css_refs set or
+ * not, cgroup removal behaves differently.
+ *
+ * If clear is set, css refcnt for the subsystem should be zero before
+ * cgroup removal can be committed.  This is implemented by
+ * CGRP_WAIT_ON_RMDIR and retry logic around ->pre_destroy(), which may be
+ * called multiple times until all css refcnts reach zero and is allowed to
+ * veto removal on any invocation.  This behavior is deprecated and will be
+ * removed as soon as the existing user (memcg) is updated.
+ *
+ * If clear is not set, each css holds an extra reference to the cgroup's
+ * dentry and cgroup removal proceeds regardless of css refs.
+ * ->pre_destroy() will be called at least once and is not allowed to fail.
+ * On the last put of each css, whenever that may be, the extra dentry ref
+ * is put so that dentry destruction happens only after all css's are
+ * released.
  */
-
 static int cgroup_clear_css_refs(struct cgroup *cgrp)
 {
 	struct cgroup_subsys *ss;
 	unsigned long flags;
 	bool failed = false;
+
 	local_irq_save(flags);
+
+	/*
+	 * Block new css_tryget() by deactivating refcnt.  If all refcnts
+	 * for subsystems w/ clear_css_refs set were 1 at the moment of
+	 * deactivation, we succeeded.
+	 */
 	for_each_subsys(cgrp->root, ss) {
 		struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
-		int refcnt;
-		while (1) {
-			/* We can only remove a CSS with a refcnt==1 */
-			refcnt = atomic_read(&css->refcnt);
-			if (refcnt > 1) {
-				failed = true;
-				goto done;
-			}
-			BUG_ON(!refcnt);
-			/*
-			 * Drop the refcnt to 0 while we check other
-			 * subsystems. This will cause any racing
-			 * css_tryget() to spin until we set the
-			 * CSS_REMOVED bits or abort
-			 */
-			if (atomic_cmpxchg(&css->refcnt, refcnt, 0) == refcnt)
-				break;
-			cpu_relax();
-		}
+
+		WARN_ON(atomic_read(&css->refcnt) < 0);
+		atomic_add(CSS_DEACT_BIAS, &css->refcnt);
+
+		if (ss->__DEPRECATED_clear_css_refs)
+			failed |= css_refcnt(css) != 1;
 	}
- done:
+
+	/*
+	 * If succeeded, set REMOVED and put all the base refs; otherwise,
+	 * restore refcnts to positive values.  Either way, all in-progress
+	 * css_tryget() will be released.
+	 */
 	for_each_subsys(cgrp->root, ss) {
 		struct cgroup_subsys_state *css = cgrp->subsys[ss->subsys_id];
-		if (failed) {
-			/*
-			 * Restore old refcnt if we previously managed
-			 * to clear it from 1 to 0
-			 */
-			if (!atomic_read(&css->refcnt))
-				atomic_set(&css->refcnt, 1);
-		} else {
-			/* Commit the fact that the CSS is removed */
+
+		if (!failed) {
 			set_bit(CSS_REMOVED, &css->flags);
+			css_put(css);
+		} else {
+			atomic_sub(CSS_DEACT_BIAS, &css->refcnt);
 		}
 	}
+
 	local_irq_restore(flags);
 	return !failed;
 }
···
 	list_del_init(&cgrp->sibling);
 	cgroup_unlock_hierarchy(cgrp->root);
 
+	list_del_init(&cgrp->allcg_node);
+
 	d = dget(cgrp->dentry);
 
 	cgroup_d_remove_dir(d);
···
 	return 0;
 }
 
+static void __init_or_module cgroup_init_cftsets(struct cgroup_subsys *ss)
+{
+	INIT_LIST_HEAD(&ss->cftsets);
+
+	/*
+	 * base_cftset is embedded in subsys itself, no need to worry about
+	 * deregistration.
+	 */
+	if (ss->base_cftypes) {
+		ss->base_cftset.cfts = ss->base_cftypes;
+		list_add_tail(&ss->base_cftset.node, &ss->cftsets);
+	}
+}
+
 static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
 {
 	struct cgroup_subsys_state *css;
 
 	printk(KERN_INFO "Initializing cgroup subsys %s\n", ss->name);
+
+	/* init base cftset */
+	cgroup_init_cftsets(ss);
 
 	/* Create the top cgroup state for this subsystem */
 	list_add(&ss->sibling, &rootnode.subsys_list);
···
 		BUG_ON(subsys[ss->subsys_id] != ss);
 		return 0;
 	}
+
+	/* init base cftset */
+	cgroup_init_cftsets(ss);
 
 	/*
 	 * need to register a subsys id before anything else - for example,
···
 }
 
 /* Caller must verify that the css is not for root cgroup */
-void __css_put(struct cgroup_subsys_state *css, int count)
+bool __css_tryget(struct cgroup_subsys_state *css)
+{
+	do {
+		int v = css_refcnt(css);
+
+		if (atomic_cmpxchg(&css->refcnt, v, v + 1) == v)
+			return true;
+		cpu_relax();
+	} while (!test_bit(CSS_REMOVED, &css->flags));
+
+	return false;
+}
+EXPORT_SYMBOL_GPL(__css_tryget);
+
+/* Caller must verify that the css is not for root cgroup */
+void __css_put(struct cgroup_subsys_state *css)
 {
 	struct cgroup *cgrp = css->cgroup;
-	int val;
+
 	rcu_read_lock();
-	val = atomic_sub_return(count, &css->refcnt);
-	if (val == 1) {
+	atomic_dec(&css->refcnt);
+	switch (css_refcnt(css)) {
+	case 1:
 		if (notify_on_release(cgrp)) {
 			set_bit(CGRP_RELEASABLE, &cgrp->flags);
 			check_for_release(cgrp);
 		}
 		cgroup_wakeup_rmdir_waiter(cgrp);
+		break;
+	case 0:
+		if (!test_bit(CSS_CLEAR_CSS_REFS, &css->flags))
+			schedule_work(&css->dput_work);
+		break;
 	}
 	rcu_read_unlock();
-	WARN_ON_ONCE(val < 1);
 }
 EXPORT_SYMBOL_GPL(__css_put);
 
···
 	 * on this or this is under rcu_read_lock(). Once css->id is allocated,
 	 * it's unchanged until freed.
 	 */
-	cssid = rcu_dereference_check(css->id, atomic_read(&css->refcnt));
+	cssid = rcu_dereference_check(css->id, css_refcnt(css));
 
 	if (cssid)
 		return cssid->id;
···
 {
 	struct css_id *cssid;
 
-	cssid = rcu_dereference_check(css->id, atomic_read(&css->refcnt));
+	cssid = rcu_dereference_check(css->id, css_refcnt(css));
 
 	if (cssid)
 		return cssid->depth;
···
 		.name = "releasable",
 		.read_u64 = releasable_read,
 	},
-};
 
-static int debug_populate(struct cgroup_subsys *ss, struct cgroup *cont)
-{
-	return cgroup_add_files(cont, ss, debug_files,
-				ARRAY_SIZE(debug_files));
-}
+	{ }	/* terminate */
+};
 
 struct cgroup_subsys debug_subsys = {
 	.name = "debug",
 	.create = debug_create,
 	.destroy = debug_destroy,
-	.populate = debug_populate,
 	.subsys_id = debug_subsys_id,
+	.base_cftypes = debug_files,
 };
 #endif /* CONFIG_CGROUP_DEBUG */

kernel/cgroup_freezer.c

···
 static struct cftype files[] = {
 	{
 		.name = "state",
+		.flags = CFTYPE_NOT_ON_ROOT,
 		.read_seq_string = freezer_read,
 		.write_string = freezer_write,
 	},
+	{ }	/* terminate */
 };
-
-static int freezer_populate(struct cgroup_subsys *ss, struct cgroup *cgroup)
-{
-	if (!cgroup->parent)
-		return 0;
-	return cgroup_add_files(cgroup, ss, files, ARRAY_SIZE(files));
-}
 
 struct cgroup_subsys freezer_subsys = {
 	.name		= "freezer",
 	.create		= freezer_create,
 	.destroy	= freezer_destroy,
-	.populate	= freezer_populate,
 	.subsys_id	= freezer_subsys_id,
 	.can_attach	= freezer_can_attach,
 	.fork		= freezer_fork,
+	.base_cftypes	= files,
 };

kernel/cpuset.c

···
 		.write_u64 = cpuset_write_u64,
 		.private = FILE_SPREAD_SLAB,
 	},
+
+	{
+		.name = "memory_pressure_enabled",
+		.flags = CFTYPE_ONLY_ON_ROOT,
+		.read_u64 = cpuset_read_u64,
+		.write_u64 = cpuset_write_u64,
+		.private = FILE_MEMORY_PRESSURE_ENABLED,
+	},
+
+	{ }	/* terminate */
 };
-
-static struct cftype cft_memory_pressure_enabled = {
-	.name = "memory_pressure_enabled",
-	.read_u64 = cpuset_read_u64,
-	.write_u64 = cpuset_write_u64,
-	.private = FILE_MEMORY_PRESSURE_ENABLED,
-};
-
-static int cpuset_populate(struct cgroup_subsys *ss, struct cgroup *cont)
-{
-	int err;
-
-	err = cgroup_add_files(cont, ss, files, ARRAY_SIZE(files));
-	if (err)
-		return err;
-	/* memory_pressure_enabled is in root cpuset only */
-	if (!cont->parent)
-		err = cgroup_add_file(cont, ss,
-				      &cft_memory_pressure_enabled);
-	return err;
-}
 
 /*
  * post_clone() is called during cgroup_create() when the
···
 	.destroy = cpuset_destroy,
 	.can_attach = cpuset_can_attach,
 	.attach = cpuset_attach,
-	.populate = cpuset_populate,
 	.post_clone = cpuset_post_clone,
 	.subsys_id = cpuset_subsys_id,
+	.base_cftypes = files,
 	.early_init = 1,
 };
 

kernel/res_counter.c

···
 	counter->parent = parent;
 }
 
-int res_counter_charge_locked(struct res_counter *counter, unsigned long val)
+int res_counter_charge_locked(struct res_counter *counter, unsigned long val,
+			      bool force)
 {
+	int ret = 0;
+
 	if (counter->usage + val > counter->limit) {
 		counter->failcnt++;
-		return -ENOMEM;
+		ret = -ENOMEM;
+		if (!force)
+			return ret;
 	}
 
 	counter->usage += val;
 	if (counter->usage > counter->max_usage)
 		counter->max_usage = counter->usage;
-	return 0;
-}
-
-int res_counter_charge(struct res_counter *counter, unsigned long val,
-			struct res_counter **limit_fail_at)
-{
-	int ret;
-	unsigned long flags;
-	struct res_counter *c, *u;
-
-	*limit_fail_at = NULL;
-	local_irq_save(flags);
-	for (c = counter; c != NULL; c = c->parent) {
-		spin_lock(&c->lock);
-		ret = res_counter_charge_locked(c, val);
-		spin_unlock(&c->lock);
-		if (ret < 0) {
-			*limit_fail_at = c;
-			goto undo;
-		}
-	}
-	ret = 0;
-	goto done;
-undo:
-	for (u = counter; u != c; u = u->parent) {
-		spin_lock(&u->lock);
-		res_counter_uncharge_locked(u, val);
-		spin_unlock(&u->lock);
-	}
-done:
-	local_irq_restore(flags);
 	return ret;
 }
 
-int res_counter_charge_nofail(struct res_counter *counter, unsigned long val,
-			      struct res_counter **limit_fail_at)
+static int __res_counter_charge(struct res_counter *counter, unsigned long val,
+				struct res_counter **limit_fail_at, bool force)
 {
 	int ret, r;
 	unsigned long flags;
-	struct res_counter *c;
+	struct res_counter *c, *u;
 
 	r = ret = 0;
 	*limit_fail_at = NULL;
 	local_irq_save(flags);
 	for (c = counter; c != NULL; c = c->parent) {
 		spin_lock(&c->lock);
-		r = res_counter_charge_locked(c, val);
-		if (r)
-			c->usage += val;
+		r = res_counter_charge_locked(c, val, force);
 		spin_unlock(&c->lock);
-		if (r < 0 && ret == 0) {
-			*limit_fail_at = c;
+		if (r < 0 && !ret) {
 			ret = r;
+			*limit_fail_at = c;
+			if (!force)
+				break;
+		}
+	}
+
+	if (ret < 0 && !force) {
+		for (u = counter; u != c; u = u->parent) {
+			spin_lock(&u->lock);
+			res_counter_uncharge_locked(u, val);
+			spin_unlock(&u->lock);
 		}
 	}
 	local_irq_restore(flags);
 
 	return ret;
 }
+
+int res_counter_charge(struct res_counter *counter, unsigned long val,
+			struct res_counter **limit_fail_at)
+{
+	return __res_counter_charge(counter, val, limit_fail_at, false);
+}
+
+int res_counter_charge_nofail(struct res_counter *counter, unsigned long val,
+			      struct res_counter **limit_fail_at)
+{
+	return __res_counter_charge(counter, val, limit_fail_at, true);
+}
+
 void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val)
 {
 	if (WARN_ON(counter->usage < val))

kernel/sched/core.c

···
 		.write_u64 = cpu_rt_period_write_uint,
 	},
 #endif
+	{ }	/* terminate */
 };
-
-static int cpu_cgroup_populate(struct cgroup_subsys *ss, struct cgroup *cont)
-{
-	return cgroup_add_files(cont, ss, cpu_files, ARRAY_SIZE(cpu_files));
-}
 
 struct cgroup_subsys cpu_cgroup_subsys = {
 	.name		= "cpu",
···
 	.can_attach	= cpu_cgroup_can_attach,
 	.attach		= cpu_cgroup_attach,
 	.exit		= cpu_cgroup_exit,
-	.populate	= cpu_cgroup_populate,
 	.subsys_id	= cpu_cgroup_subsys_id,
+	.base_cftypes	= cpu_files,
 	.early_init	= 1,
 };
 
···
 		.name = "stat",
 		.read_map = cpuacct_stats_show,
 	},
+	{ }	/* terminate */
 };
-
-static int cpuacct_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
-{
-	return cgroup_add_files(cgrp, ss, files, ARRAY_SIZE(files));
-}
 
 /*
  * charge this task's execution time to its accounting group.
···
 	.name = "cpuacct",
 	.create = cpuacct_create,
 	.destroy = cpuacct_destroy,
-	.populate = cpuacct_populate,
 	.subsys_id = cpuacct_subsys_id,
+	.base_cftypes = files,
 };
 #endif	/* CONFIG_CGROUP_CPUACCT */

mm/memcontrol.c

···
 	return val << PAGE_SHIFT;
 }
 
-static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
+static ssize_t mem_cgroup_read(struct cgroup *cont, struct cftype *cft,
+			       struct file *file, char __user *buf,
+			       size_t nbytes, loff_t *ppos)
 {
 	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+	char str[64];
 	u64 val;
-	int type, name;
+	int type, name, len;
 
 	type = MEMFILE_TYPE(cft->private);
 	name = MEMFILE_ATTR(cft->private);
+
+	if (!do_swap_account && type == _MEMSWAP)
+		return -EOPNOTSUPP;
+
 	switch (type) {
 	case _MEM:
 		if (name == RES_USAGE)
···
 	default:
 		BUG();
 	}
-	return val;
+
+	len = scnprintf(str, sizeof(str), "%llu\n", (unsigned long long)val);
+	return simple_read_from_buffer(buf, nbytes, ppos, str, len);
 }
 /*
  * The user of this function is...
···
 
 	type = MEMFILE_TYPE(cft->private);
 	name = MEMFILE_ATTR(cft->private);
+
+	if (!do_swap_account && type == _MEMSWAP)
+		return -EOPNOTSUPP;
+
 	switch (name) {
 	case RES_LIMIT:
 		if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
···
 
 static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
 {
-	struct mem_cgroup *memcg;
+	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
 	int type, name;
 
-	memcg = mem_cgroup_from_cont(cont);
 	type = MEMFILE_TYPE(event);
 	name = MEMFILE_ATTR(event);
+
+	if (!do_swap_account && type == _MEMSWAP)
+		return -EOPNOTSUPP;
+
 	switch (name) {
 	case RES_MAX_USAGE:
 		if (type == _MEM)
···
 #endif /* CONFIG_NUMA */
 
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
-static int register_kmem_files(struct cgroup *cont, struct cgroup_subsys *ss)
+static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
 {
-	/*
-	 * Part of this would be better living in a separate allocation
-	 * function, leaving us with just the cgroup tree population work.
-	 * We, however, depend on state such as network's proto_list that
-	 * is only initialized after cgroup creation. I found the less
-	 * cumbersome way to deal with it to defer it all to populate time
-	 */
-	return mem_cgroup_sockets_init(cont, ss);
+	return mem_cgroup_sockets_init(memcg, ss);
 };
 
-static void kmem_cgroup_destroy(struct cgroup *cont)
+static void kmem_cgroup_destroy(struct mem_cgroup *memcg)
 {
-	mem_cgroup_sockets_destroy(cont);
+	mem_cgroup_sockets_destroy(memcg);
 }
 #else
-static int register_kmem_files(struct cgroup *cont, struct cgroup_subsys *ss)
+static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
 {
 	return 0;
 }
 
-static void kmem_cgroup_destroy(struct cgroup *cont)
+static void kmem_cgroup_destroy(struct mem_cgroup *memcg)
 {
 }
 #endif
···
 	{
 		.name = "usage_in_bytes",
 		.private = MEMFILE_PRIVATE(_MEM, RES_USAGE),
-		.read_u64 = mem_cgroup_read,
+		.read = mem_cgroup_read,
 		.register_event = mem_cgroup_usage_register_event,
 		.unregister_event = mem_cgroup_usage_unregister_event,
 	},
···
 		.name = "max_usage_in_bytes",
 		.private = MEMFILE_PRIVATE(_MEM, RES_MAX_USAGE),
 		.trigger = mem_cgroup_reset,
-		.read_u64 = mem_cgroup_read,
+		.read = mem_cgroup_read,
 	},
 	{
 		.name = "limit_in_bytes",
 		.private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
 		.write_string = mem_cgroup_write,
-		.read_u64 = mem_cgroup_read,
+		.read = mem_cgroup_read,
 	},
 	{
 		.name = "soft_limit_in_bytes",
 		.private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
 		.write_string = mem_cgroup_write,
-		.read_u64 = mem_cgroup_read,
+		.read = mem_cgroup_read,
 	},
 	{
 		.name = "failcnt",
 		.private = MEMFILE_PRIVATE(_MEM, RES_FAILCNT),
 		.trigger = mem_cgroup_reset,
-		.read_u64 = mem_cgroup_read,
+		.read = mem_cgroup_read,
 	},
 	{
 		.name = "stat",
···
 		.mode = S_IRUGO,
 	},
 #endif
-};
-
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
-static struct cftype memsw_cgroup_files[] = {
 	{
 		.name = "memsw.usage_in_bytes",
 		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
-		.read_u64 = mem_cgroup_read,
+		.read = mem_cgroup_read,
 		.register_event = mem_cgroup_usage_register_event,
 		.unregister_event = mem_cgroup_usage_unregister_event,
 	},
···
 		.name = "memsw.max_usage_in_bytes",
 		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE),
 		.trigger = mem_cgroup_reset,
-		.read_u64 = mem_cgroup_read,
+		.read = mem_cgroup_read,
 	},
 	{
 		.name = "memsw.limit_in_bytes",
 		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT),
 		.write_string = mem_cgroup_write,
-		.read_u64 = mem_cgroup_read,
+		.read = mem_cgroup_read,
 	},
 	{
 		.name = "memsw.failcnt",
 		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT),
 		.trigger = mem_cgroup_reset,
-		.read_u64 = mem_cgroup_read,
+		.read = mem_cgroup_read,
 	},
-};
-
-static int register_memsw_files(struct cgroup *cont, struct cgroup_subsys *ss)
-{
-	if (!do_swap_account)
-		return 0;
-	return cgroup_add_files(cont, ss, memsw_cgroup_files,
-				ARRAY_SIZE(memsw_cgroup_files));
-};
-#else
-static int register_memsw_files(struct cgroup *cont, struct cgroup_subsys *ss)
-{
-	return 0;
-}
 #endif
+	{ },	/* terminate */
+};
 
 static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node)
 {
···
 	memcg->move_charge_at_immigrate = 0;
 	mutex_init(&memcg->thresholds_lock);
 	spin_lock_init(&memcg->move_lock);
+
+	error = memcg_init_kmem(memcg, &mem_cgroup_subsys);
+	if (error) {
+		/*
+		 * We call put now because our (and parent's) refcnts
+		 * are already in place. mem_cgroup_put() will internally
+		 * call __mem_cgroup_free, so return directly
+		 */
+		mem_cgroup_put(memcg);
+		return ERR_PTR(error);
+	}
 	return &memcg->css;
 free_out:
 	__mem_cgroup_free(memcg);
···
 {
 	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
 
-	kmem_cgroup_destroy(cont);
+	kmem_cgroup_destroy(memcg);
 
 	mem_cgroup_put(memcg);
-}
-
-static int mem_cgroup_populate(struct cgroup_subsys *ss,
-				struct cgroup *cont)
-{
-	int ret;
-
-	ret = cgroup_add_files(cont, ss, mem_cgroup_files,
-				ARRAY_SIZE(mem_cgroup_files));
-
-	if (!ret)
-		ret = register_memsw_files(cont, ss);
-
-	if (!ret)
-		ret = register_kmem_files(cont, ss);
-
-	return ret;
 }
 
 #ifdef CONFIG_MMU
···
 	.create = mem_cgroup_create,
 	.pre_destroy = mem_cgroup_pre_destroy,
 	.destroy = mem_cgroup_destroy,
-	.populate = mem_cgroup_populate,
 	.can_attach = mem_cgroup_can_attach,
 	.cancel_attach = mem_cgroup_cancel_attach,
 	.attach = mem_cgroup_move_task,
+	.base_cftypes = mem_cgroup_files,
 	.early_init = 0,
 	.use_id = 1,
+	.__DEPRECATED_clear_css_refs = true,
 };
 
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP

net/core/netprio_cgroup.c

···
 #include <net/sock.h>
 #include <net/netprio_cgroup.h>
 
-static struct cgroup_subsys_state *cgrp_create(struct cgroup *cgrp);
-static void cgrp_destroy(struct cgroup *cgrp);
-static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp);
-
-struct cgroup_subsys net_prio_subsys = {
-	.name		= "net_prio",
-	.create		= cgrp_create,
-	.destroy	= cgrp_destroy,
-	.populate	= cgrp_populate,
-#ifdef CONFIG_NETPRIO_CGROUP
-	.subsys_id	= net_prio_subsys_id,
-#endif
-	.module		= THIS_MODULE
-};
-
 #define PRIOIDX_SZ 128
 
 static unsigned long prioidx_map[PRIOIDX_SZ];
···
 		.read_map = read_priomap,
 		.write_string = write_priomap,
 	},
+	{ }	/* terminate */
 };
 
-static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
-{
-	return cgroup_add_files(cgrp, ss, ss_files, ARRAY_SIZE(ss_files));
-}
+struct cgroup_subsys net_prio_subsys = {
+	.name		= "net_prio",
+	.create		= cgrp_create,
+	.destroy	= cgrp_destroy,
+#ifdef CONFIG_NETPRIO_CGROUP
+	.subsys_id	= net_prio_subsys_id,
+#endif
+	.base_cftypes	= ss_files,
+	.module		= THIS_MODULE
+};
 
 static int netprio_device_event(struct notifier_block *unused,
 				unsigned long event, void *ptr)

net/core/sock.c

···
 static LIST_HEAD(proto_list);
 
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
-int mem_cgroup_sockets_init(struct cgroup *cgrp, struct cgroup_subsys *ss)
+int mem_cgroup_sockets_init(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
 {
 	struct proto *proto;
 	int ret = 0;
···
 	mutex_lock(&proto_list_mutex);
 	list_for_each_entry(proto, &proto_list, node) {
 		if (proto->init_cgroup) {
-			ret = proto->init_cgroup(cgrp, ss);
+			ret = proto->init_cgroup(memcg, ss);
 			if (ret)
 				goto out;
 		}
···
 out:
 	list_for_each_entry_continue_reverse(proto, &proto_list, node)
 		if (proto->destroy_cgroup)
-			proto->destroy_cgroup(cgrp);
+			proto->destroy_cgroup(memcg);
 	mutex_unlock(&proto_list_mutex);
 	return ret;
 }
 
-void mem_cgroup_sockets_destroy(struct cgroup *cgrp)
+void mem_cgroup_sockets_destroy(struct mem_cgroup *memcg)
 {
 	struct proto *proto;
 
 	mutex_lock(&proto_list_mutex);
 	list_for_each_entry_reverse(proto, &proto_list, node)
 		if (proto->destroy_cgroup)
-			proto->destroy_cgroup(cgrp);
+			proto->destroy_cgroup(memcg);
 	mutex_unlock(&proto_list_mutex);
 }
 #endif

net/ipv4/tcp_memcontrol.c

···
 #include <linux/memcontrol.h>
 #include <linux/module.h>
 
-static u64 tcp_cgroup_read(struct cgroup *cont, struct cftype *cft);
-static int tcp_cgroup_write(struct cgroup *cont, struct cftype *cft,
-			    const char *buffer);
-static int tcp_cgroup_reset(struct cgroup *cont, unsigned int event);
-
-static struct cftype tcp_files[] = {
-	{
-		.name = "kmem.tcp.limit_in_bytes",
-		.write_string = tcp_cgroup_write,
-		.read_u64 = tcp_cgroup_read,
-		.private = RES_LIMIT,
-	},
-	{
-		.name = "kmem.tcp.usage_in_bytes",
-		.read_u64 = tcp_cgroup_read,
-		.private = RES_USAGE,
-	},
-	{
-		.name = "kmem.tcp.failcnt",
-		.private = RES_FAILCNT,
-		.trigger = tcp_cgroup_reset,
-		.read_u64 = tcp_cgroup_read,
-	},
-	{
-		.name = "kmem.tcp.max_usage_in_bytes",
-		.private = RES_MAX_USAGE,
-		.trigger = tcp_cgroup_reset,
-		.read_u64 = tcp_cgroup_read,
-	},
-};
-
 static inline struct tcp_memcontrol *tcp_from_cgproto(struct cg_proto *cg_proto)
 {
 	return container_of(cg_proto, struct tcp_memcontrol, cg_proto);
···
 }
 EXPORT_SYMBOL(memcg_tcp_enter_memory_pressure);
 
-int tcp_init_cgroup(struct cgroup *cgrp, struct cgroup_subsys *ss)
+int tcp_init_cgroup(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
 {
 	/*
 	 * The root cgroup does not use res_counters, but rather,
···
 	struct res_counter *res_parent = NULL;
 	struct cg_proto *cg_proto, *parent_cg;
 	struct tcp_memcontrol *tcp;
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
 	struct mem_cgroup *parent = parent_mem_cgroup(memcg);
 	struct net *net = current->nsproxy->net_ns;
 
 	cg_proto = tcp_prot.proto_cgroup(memcg);
 	if (!cg_proto)
-		goto create_files;
+		return 0;
 
 	tcp = tcp_from_cgproto(cg_proto);
 
···
 	cg_proto->sockets_allocated = &tcp->tcp_sockets_allocated;
 	cg_proto->memcg = memcg;
 
-create_files:
-	return cgroup_add_files(cgrp, ss, tcp_files,
-				ARRAY_SIZE(tcp_files));
+	return 0;
 }
 EXPORT_SYMBOL(tcp_init_cgroup);
 
-void tcp_destroy_cgroup(struct cgroup *cgrp)
+void tcp_destroy_cgroup(struct mem_cgroup *memcg)
 {
-	struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp);
 	struct cg_proto *cg_proto;
 	struct tcp_memcontrol *tcp;
 	u64 val;
···
 
 	tcp->tcp_prot_mem[idx] = val;
 }
+
+static struct cftype tcp_files[] = {
+	{
+		.name = "kmem.tcp.limit_in_bytes",
+		.write_string = tcp_cgroup_write,
+		.read_u64 = tcp_cgroup_read,
+		.private = RES_LIMIT,
+	},
+	{
+		.name = "kmem.tcp.usage_in_bytes",
+		.read_u64 = tcp_cgroup_read,
+		.private = RES_USAGE,
+	},
+	{
+		.name = "kmem.tcp.failcnt",
+		.private = RES_FAILCNT,
+		.trigger = tcp_cgroup_reset,
+		.read_u64 = tcp_cgroup_read,
+	},
+	{
+		.name = "kmem.tcp.max_usage_in_bytes",
+		.private = RES_MAX_USAGE,
+		.trigger = tcp_cgroup_reset,
+		.read_u64 = tcp_cgroup_read,
+	},
+	{ }	/* terminate */
+};
+
+static int __init tcp_memcontrol_init(void)
+{
+	WARN_ON(cgroup_add_cftypes(&mem_cgroup_subsys, tcp_files));
+	return 0;
+}
+__initcall(tcp_memcontrol_init);

net/sched/cls_cgroup.c

···
 #include <net/sock.h>
 #include <net/cls_cgroup.h>
 
-static struct cgroup_subsys_state *cgrp_create(struct cgroup *cgrp);
-static void cgrp_destroy(struct cgroup *cgrp);
-static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp);
-
-struct cgroup_subsys net_cls_subsys = {
-	.name		= "net_cls",
-	.create		= cgrp_create,
-	.destroy	= cgrp_destroy,
-	.populate	= cgrp_populate,
-#ifdef CONFIG_NET_CLS_CGROUP
-	.subsys_id	= net_cls_subsys_id,
-#endif
-	.module		= THIS_MODULE,
-};
-
-
 static inline struct cgroup_cls_state *cgrp_cls_state(struct cgroup *cgrp)
 {
 	return container_of(cgroup_subsys_state(cgrp, net_cls_subsys_id),
···
 		.read_u64 = read_classid,
 		.write_u64 = write_classid,
 	},
+	{ }	/* terminate */
 };
 
-static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
-{
-	return cgroup_add_files(cgrp, ss, ss_files, ARRAY_SIZE(ss_files));
-}
+struct cgroup_subsys net_cls_subsys = {
+	.name		= "net_cls",
+	.create		= cgrp_create,
+	.destroy	= cgrp_destroy,
+#ifdef CONFIG_NET_CLS_CGROUP
+	.subsys_id	= net_cls_subsys_id,
+#endif
+	.base_cftypes	= ss_files,
+	.module		= THIS_MODULE,
+};
 
 struct cls_cgroup_head {
 	u32			handle;

security/device_cgroup.c

···
 		.read_seq_string = devcgroup_seq_read,
 		.private = DEVCG_LIST,
 	},
+	{ }	/* terminate */
 };
-
-static int devcgroup_populate(struct cgroup_subsys *ss,
-				struct cgroup *cgroup)
-{
-	return cgroup_add_files(cgroup, ss, dev_cgroup_files,
-					ARRAY_SIZE(dev_cgroup_files));
-}
 
 struct cgroup_subsys devices_subsys = {
 	.name = "devices",
 	.can_attach = devcgroup_can_attach,
 	.create = devcgroup_create,
 	.destroy = devcgroup_destroy,
-	.populate = devcgroup_populate,
 	.subsys_id = devices_subsys_id,
+	.base_cftypes = dev_cgroup_files,
 };
 
 int __devcgroup_inode_permission(struct inode *inode, int mask)