Merge tag 'cgroup-for-6.15-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull cgroup fixes from Tejun Heo:

 - A number of cpuset remote partition related fixes and cleanups along
   with selftest updates.

 - A change from this merge window made cgroup_rstat_updated_list()
   called outside cgroup_rstat_lock leading to list corruptions. Fix it
   by relocating the call inside the lock.

* tag 'cgroup-for-6.15-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup/cpuset: Fix race between newly created partition and dying one
  cgroup: rstat: call cgroup_rstat_updated_list with cgroup_rstat_lock
  selftest/cgroup: Add a remote partition transition test to test_cpuset_prs.sh
  selftest/cgroup: Clean up and restructure test_cpuset_prs.sh
  selftest/cgroup: Update test_cpuset_prs.sh to use | as effective CPUs and state separator
  cgroup/cpuset: Remove unneeded goto in sched_partition_write() and rename it
  cgroup/cpuset: Code cleanup and comment update
  cgroup/cpuset: Don't allow creation of local partition over a remote one
  cgroup/cpuset: Remove remote_partition_check() & make update_cpumasks_hier() handle remote partition
  cgroup/cpuset: Fix error handling in remote_partition_disable()
  cgroup/cpuset: Fix incorrect isolated_cpus update in update_parent_effective_cpumask()

Author: torvalds

include/linux/cgroup-defs.h

@@ -710,6 +710,7 @@ struct cgroup_subsys {
 	void (*css_released)(struct cgroup_subsys_state *css);
 	void (*css_free)(struct cgroup_subsys_state *css);
 	void (*css_reset)(struct cgroup_subsys_state *css);
+	void (*css_killed)(struct cgroup_subsys_state *css);
 	void (*css_rstat_flush)(struct cgroup_subsys_state *css, int cpu);
 	int (*css_extra_stat_show)(struct seq_file *seq,
 				   struct cgroup_subsys_state *css);

include/linux/cgroup.h

@@ -344,7 +344,7 @@ static inline u64 cgroup_id(const struct cgroup *cgrp)
  */
 static inline bool css_is_dying(struct cgroup_subsys_state *css)
 {
-	return !(css->flags & CSS_NO_REF) && percpu_ref_is_dying(&css->refcnt);
+	return css->flags & CSS_DYING;
 }
 
 static inline void cgroup_get(struct cgroup *cgrp)

kernel/cgroup/cgroup.c

@@ -5923,6 +5923,12 @@ static void kill_css(struct cgroup_subsys_state *css)
 	if (css->flags & CSS_DYING)
 		return;
 
+	/*
+	 * Call css_killed(), if defined, before setting the CSS_DYING flag
+	 */
+	if (css->ss->css_killed)
+		css->ss->css_killed(css);
+
 	css->flags |= CSS_DYING;
 
 	/*

kernel/cgroup/cpuset-internal.h

@@ -33,6 +33,7 @@ enum prs_errcode {
 	PERR_CPUSEMPTY,
 	PERR_HKEEPING,
 	PERR_ACCESS,
+	PERR_REMOTE,
 };
 
 /* bits in struct cpuset flags field */