Merge tag 'cgroup-for-6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull cgroup updates from Tejun Heo:

 - The locking around cpuset hotplug processing has always been a bit of
   mess which was worked around by making hotplug processing
   asynchronous. The asynchronity isn't great and led to other issues.

   We tried to make the behavior synchronous a while ago but that led to
   lockdep splats. Waiman took another stab at cleaning up and making it
   synchronous. The patch has been in -next for well over a month and
   there haven't been any complaints, so fingers crossed.

 - Tracepoints added to help understanding rstat lock contentions.

 - A bunch of minor changes - doc updates, code cleanups and selftests.

* tag 'cgroup-for-6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (24 commits)
  cgroup/rstat: add cgroup_rstat_cpu_lock helpers and tracepoints
  selftests/cgroup: Drop define _GNU_SOURCE
  docs: cgroup-v1: Update page cache removal functions
  selftests/cgroup: fix uninitialized variables in test_zswap.c
  selftests/cgroup: cpu_hogger init: use {} instead of {NULL}
  selftests/cgroup: fix clang warnings: uninitialized fd variable
  selftests/cgroup: fix clang build failures for abs() calls
  cgroup/cpuset: Remove outdated comment in sched_partition_write()
  cgroup/cpuset: Fix incorrect top_cpuset flags
  cgroup/cpuset: Avoid clearing CS_SCHED_LOAD_BALANCE twice
  cgroup/cpuset: Statically initialize more members of top_cpuset
  cgroup: Avoid unnecessary looping in cgroup_no_v1()
  cgroup, legacy_freezer: update comment for freezer_css_offline()
  docs, cgroup: add entries for pids to cgroup-v2.rst
  cgroup: don't call cgroup1_pidlist_destroy_all() for v2
  cgroup_freezer: update comment for freezer_css_online()
  cgroup/rstat: desc member cgrp in cgroup_rstat_flush_release
  cgroup/rstat: add cgroup_rstat_lock helpers and tracepoints
  cgroup/pids: Remove superfluous zeroing
  docs: cgroup-v1: Fix description for css_online
  ...

3 files changed, 93 insertions, 4 deletions

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 34aaf0e87def..2150ca60394b 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -690,7 +690,7 @@ static inline void cgroup_path_from_kernfs_id(u64 id, char *buf, size_t buflen)
 void cgroup_rstat_updated(struct cgroup *cgrp, int cpu);
 void cgroup_rstat_flush(struct cgroup *cgrp);
 void cgroup_rstat_flush_hold(struct cgroup *cgrp);
-void cgroup_rstat_flush_release(void);
+void cgroup_rstat_flush_release(struct cgroup *cgrp);
 
 /*
  * Basic resource stats.
diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index 0ce6ff0d9c9a..de4cf0ee96f7 100644
--- a/include/linux/cpuset.h
+++ b/include/linux/cpuset.h
@@ -70,7 +70,6 @@ extern int cpuset_init(void);
 extern void cpuset_init_smp(void);
 extern void cpuset_force_rebuild(void);
 extern void cpuset_update_active_cpus(void);
-extern void cpuset_wait_for_hotplug(void);
 extern void inc_dl_tasks_cs(struct task_struct *task);
 extern void dec_dl_tasks_cs(struct task_struct *task);
 extern void cpuset_lock(void);
@@ -185,8 +184,6 @@ static inline void cpuset_update_active_cpus(void)
 	partition_sched_domains(1, NULL, NULL);
 }
 
-static inline void cpuset_wait_for_hotplug(void) { }
-
 static inline void inc_dl_tasks_cs(struct task_struct *task) { }
 static inline void dec_dl_tasks_cs(struct task_struct *task) { }
 static inline void cpuset_lock(void) { }
diff --git a/include/trace/events/cgroup.h b/include/trace/events/cgroup.h
index dd7d7c9efecd..0b95865a90f3 100644
--- a/include/trace/events/cgroup.h
+++ b/include/trace/events/cgroup.h
@@ -204,6 +204,98 @@ DEFINE_EVENT(cgroup_event, cgroup_notify_frozen,
 	TP_ARGS(cgrp, path, val)
 );
 
+DECLARE_EVENT_CLASS(cgroup_rstat,
+
+	TP_PROTO(struct cgroup *cgrp, int cpu, bool contended),
+
+	TP_ARGS(cgrp, cpu, contended),
+
+	TP_STRUCT__entry(
+		__field(	int,		root			)
+		__field(	int,		level			)
+		__field(	u64,		id			)
+		__field(	int,		cpu			)
+		__field(	bool,		contended		)
+	),
+
+	TP_fast_assign(
+		__entry->root = cgrp->root->hierarchy_id;
+		__entry->id = cgroup_id(cgrp);
+		__entry->level = cgrp->level;
+		__entry->cpu = cpu;
+		__entry->contended = contended;
+	),
+
+	TP_printk("root=%d id=%llu level=%d cpu=%d lock contended:%d",
+		  __entry->root, __entry->id, __entry->level,
+		  __entry->cpu, __entry->contended)
+);
+
+/* Related to global: cgroup_rstat_lock */
+DEFINE_EVENT(cgroup_rstat, cgroup_rstat_lock_contended,
+
+	TP_PROTO(struct cgroup *cgrp, int cpu, bool contended),
+
+	TP_ARGS(cgrp, cpu, contended)
+);
+
+DEFINE_EVENT(cgroup_rstat, cgroup_rstat_locked,
+
+	TP_PROTO(struct cgroup *cgrp, int cpu, bool contended),
+
+	TP_ARGS(cgrp, cpu, contended)
+);
+
+DEFINE_EVENT(cgroup_rstat, cgroup_rstat_unlock,
+
+	TP_PROTO(struct cgroup *cgrp, int cpu, bool contended),
+
+	TP_ARGS(cgrp, cpu, contended)
+);
+
+/* Related to per CPU: cgroup_rstat_cpu_lock */
+DEFINE_EVENT(cgroup_rstat, cgroup_rstat_cpu_lock_contended,
+
+	TP_PROTO(struct cgroup *cgrp, int cpu, bool contended),
+
+	TP_ARGS(cgrp, cpu, contended)
+);
+
+DEFINE_EVENT(cgroup_rstat, cgroup_rstat_cpu_lock_contended_fastpath,
+
+	TP_PROTO(struct cgroup *cgrp, int cpu, bool contended),
+
+	TP_ARGS(cgrp, cpu, contended)
+);
+
+DEFINE_EVENT(cgroup_rstat, cgroup_rstat_cpu_locked,
+
+	TP_PROTO(struct cgroup *cgrp, int cpu, bool contended),
+
+	TP_ARGS(cgrp, cpu, contended)
+);
+
+DEFINE_EVENT(cgroup_rstat, cgroup_rstat_cpu_locked_fastpath,
+
+	TP_PROTO(struct cgroup *cgrp, int cpu, bool contended),
+
+	TP_ARGS(cgrp, cpu, contended)
+);
+
+DEFINE_EVENT(cgroup_rstat, cgroup_rstat_cpu_unlock,
+
+	TP_PROTO(struct cgroup *cgrp, int cpu, bool contended),
+
+	TP_ARGS(cgrp, cpu, contended)
+);
+
+DEFINE_EVENT(cgroup_rstat, cgroup_rstat_cpu_unlock_fastpath,
+
+	TP_PROTO(struct cgroup *cgrp, int cpu, bool contended),
+
+	TP_ARGS(cgrp, cpu, contended)
+);
+
 #endif /* _TRACE_CGROUP_H */
 
 /* This part must be outside protection */