Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index 22254c1..430e219 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -20,6 +20,7 @@
 #include <linux/u64_stats_sync.h>
 #include <linux/workqueue.h>
 #include <linux/bpf-cgroup.h>
+#include <linux/psi_types.h>
 
 #ifdef CONFIG_CGROUPS
 
@@ -31,6 +32,7 @@
 struct kernfs_ops;
 struct kernfs_open_file;
 struct seq_file;
+struct poll_table_struct;
 
 #define MAX_CGROUP_TYPE_NAMELEN 32
 #define MAX_CGROUP_ROOT_NAMELEN 64
@@ -63,6 +65,12 @@
 	 * specified at mount time and thus is implemented here.
 	 */
 	CGRP_CPUSET_CLONE_CHILDREN,
+
+	/* Control group has to be frozen. */
+	CGRP_FREEZE,
+
+	/* Cgroup is frozen. */
+	CGRP_FROZEN,
 };
 
 /* cgroup_root->flags */
@@ -81,6 +89,11 @@
 	 * Enable cpuset controller in v1 cgroup to use v2 behavior.
 	 */
 	CGRP_ROOT_CPUSET_V2_MODE = (1 << 4),
+
+	/*
+	 * Enable legacy local memory.events.
+	 */
+	CGRP_ROOT_MEMORY_LOCAL_EVENTS = (1 << 5),
 };
 
 /* cftype->flags */
@@ -91,6 +104,7 @@
 
 	CFTYPE_NO_PREFIX	= (1 << 3),	/* (DON'T USE FOR NEW FILES) no subsys prefix */
 	CFTYPE_WORLD_WRITABLE	= (1 << 4),	/* (DON'T USE FOR NEW FILES) S_IWUGO */
+	CFTYPE_DEBUG		= (1 << 5),	/* create when cgroup_debug */
 
 	/* internal flags, do not use outside cgroup core proper */
 	__CFTYPE_ONLY_ON_DFL	= (1 << 16),	/* only on default hierarchy */
@@ -207,6 +221,7 @@
 	 */
 	struct list_head tasks;
 	struct list_head mg_tasks;
+	struct list_head dying_tasks;
 
 	/* all css_task_iters currently walking this cset */
 	struct list_head task_iters;
@@ -314,6 +329,25 @@
 	struct cgroup *updated_next;		/* NULL iff not on the list */
 };
 
+struct cgroup_freezer_state {
+	/* Should the cgroup and its descendants be frozen. */
+	bool freeze;
+
+	/* Should the cgroup actually be frozen? */
+	int e_freeze;
+
+	/* Fields below are protected by css_set_lock */
+
+	/* Number of frozen descendant cgroups */
+	int nr_frozen_descendants;
+
+	/*
+	 * Number of tasks, which are counted as frozen:
+	 * frozen, SIGSTOPped, and PTRACEd.
+	 */
+	int nr_frozen_tasks;
+};
+
 struct cgroup {
 	/* self css with NULL ->ss, points back to this cgroup */
 	struct cgroup_subsys_state self;
@@ -346,6 +380,11 @@
 	 * Dying cgroups are cgroups which were deleted by a user,
 	 * but are still existing because someone else is holding a reference.
 	 * max_descendants is a maximum allowed number of descent cgroups.
+	 *
+	 * nr_descendants and nr_dying_descendants are protected
+	 * by cgroup_mutex and css_set_lock. It's fine to read them holding
+	 * any of cgroup_mutex and css_set_lock; for writing both locks
+	 * should be held.
 	 */
 	int nr_descendants;
 	int nr_dying_descendants;
@@ -436,12 +475,18 @@
 	/* used to schedule release agent */
 	struct work_struct release_agent_work;
 
+	/* used to track pressure stalls */
+	struct psi_group psi;
+
 	/* used to store eBPF programs */
 	struct cgroup_bpf bpf;
 
 	/* If there is block congestion on this cgroup. */
 	atomic_t congestion_count;
 
+	/* Used to store internal freezer state */
+	struct cgroup_freezer_state freezer;
+
 	/* ids of the ancestors at each level including self */
 	int ancestor_ids[];
 };
@@ -569,6 +614,9 @@
 	ssize_t (*write)(struct kernfs_open_file *of,
 			 char *buf, size_t nbytes, loff_t off);
 
+	__poll_t (*poll)(struct kernfs_open_file *of,
+			 struct poll_table_struct *pt);
+
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 	struct lock_class_key	lockdep_key;
 #endif
@@ -576,7 +624,7 @@
 
 /*
  * Control Group subsystem type.
- * See Documentation/cgroup-v1/cgroups.txt for details
+ * See Documentation/admin-guide/cgroup-v1/cgroups.rst for details
  */
 struct cgroup_subsys {
 	struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css);
@@ -597,7 +645,7 @@
 	void (*cancel_fork)(struct task_struct *task);
 	void (*fork)(struct task_struct *task);
 	void (*exit)(struct task_struct *task);
-	void (*free)(struct task_struct *task);
+	void (*release)(struct task_struct *task);
 	void (*bind)(struct cgroup_subsys_state *root_css);
 
 	bool early_init:1;