Merge tag 'cgroup-for-6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull cgroup updates from Tejun Heo:

 - Added Michal Koutný as a maintainer

 - Counters in pids.events were behaving inconsistently. pids.events
   made properly hierarchical and pids.events.local added

 - misc.peak and misc.events.local added

 - cpuset remote partition creation and cpuset.cpus.exclusive handling
   improved

 - Code cleanups, non-critical fixes, doc updates

 - for-6.10-fixes is merged in to receive two non-critical fixes that
   didn't trigger pull

* tag 'cgroup-for-6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (23 commits)
  cgroup: Add Michal Koutný as a maintainer
  cgroup/misc: Introduce misc.events.local
  cgroup/rstat: add force idle show helper
  cgroup: Protect css->cgroup write under css_set_lock
  cgroup/misc: Introduce misc.peak
  cgroup_misc: add kernel-doc comments for enum misc_res_type
  cgroup/cpuset: Prevent UAF in proc_cpuset_show()
  selftest/cgroup: Update test_cpuset_prs.sh to match changes
  cgroup/cpuset: Make cpuset.cpus.exclusive independent of cpuset.cpus
  cgroup/cpuset: Delay setting of CS_CPU_EXCLUSIVE until valid partition
  selftest/cgroup: Fix test_cpuset_prs.sh problems reported by test robot
  cgroup/cpuset: Fix remote root partition creation problem
  cgroup: avoid the unnecessary list_add(dying_tasks) in cgroup_exit()
  cgroup/cpuset: Optimize isolated partition only generate_sched_domains() calls
  cgroup/cpuset: Reduce the lock protecting CS_SCHED_LOAD_BALANCE
  kernel/cgroup: cleanup cgroup_base_files when fail to add cgroup_psi_files
  selftests: cgroup: Add basic tests for pids controller
  selftests: cgroup: Lexicographic order in Makefile
  cgroup/pids: Add pids.events.local
  cgroup/pids: Make event counters hierarchical
  ...

Author: torvalds

Documentation/admin-guide/cgroup-v1/pids.rst

@@ -36,7 +36,8 @@ superset of parent/child/pids.current.
 
 The pids.events file contains event counters:
 
-  - max: Number of times fork failed because limit was hit.
+  - max: Number of times fork failed in the cgroup because limit was hit in
+    self or ancestors.
 
 Example
 -------

Documentation/admin-guide/cgroup-v2.rst

@@ -239,6 +239,13 @@ cgroup v2 currently supports the following mount options.
           will not be tracked by the memory controller (even if cgroup
           v2 is remounted later on).
 
+  pids_localevents
+        The option restores v1-like behavior of pids.events:max, that is only
+        local (inside cgroup proper) fork failures are counted. Without this
+        option pids.events.max represents any pids.max enforcemnt across
+        cgroup's subtree.
+
+
 
 Organizing Processes and Threads
 --------------------------------
@@ -2205,12 +2212,18 @@ PID Interface Files
 	descendants has ever reached.
 
   pids.events
-	A read-only flat-keyed file which exists on non-root cgroups. The
-	following entries are defined. Unless specified otherwise, a value
-	change in this file generates a file modified event.
+	A read-only flat-keyed file which exists on non-root cgroups. Unless
+	specified otherwise, a value change in this file generates a file
+	modified event. The following entries are defined.
 
 	  max
-		Number of times fork failed because limit was hit.
+		The number of times the cgroup's total number of processes hit the pids.max
+		limit (see also pids_localevents).
+
+  pids.events.local
+	Similar to pids.events but the fields in the file are local
+	to the cgroup i.e. not hierarchical. The file modified event
+	generated on this file reflects only the local events.
 
 Organisational operations are not blocked by cgroup policies, so it is
 possible to have pids.current > pids.max.  This can be done by either
@@ -2346,8 +2359,12 @@ Cpuset Interface Files
 	is always a subset of it.
 
 	Users can manually set it to a value that is different from
-	"cpuset.cpus".	The only constraint in setting it is that the
-	list of CPUs must be exclusive with respect to its sibling.
+	"cpuset.cpus".	One constraint in setting it is that the list of
+	CPUs must be exclusive with respect to "cpuset.cpus.exclusive"
+	of its sibling.  If "cpuset.cpus.exclusive" of a sibling cgroup
+	isn't set, its "cpuset.cpus" value, if set, cannot be a subset
+	of it to leave at least one CPU available when the exclusive
+	CPUs are taken away.
 
 	For a parent cgroup, any one of its exclusive CPUs can only
 	be distributed to at most one of its child cgroups.  Having an
@@ -2363,8 +2380,8 @@ Cpuset Interface Files
 	cpuset-enabled cgroups.
 
 	This file shows the effective set of exclusive CPUs that
-	can be used to create a partition root.  The content of this
-	file will always be a subset of "cpuset.cpus" and its parent's
+	can be used to create a partition root.  The content
+	of this file will always be a subset of its parent's
 	"cpuset.cpus.exclusive.effective" if its parent is not the root
 	cgroup.  It will also be a subset of "cpuset.cpus.exclusive"
 	if it is set.  If "cpuset.cpus.exclusive" is not set, it is
@@ -2625,6 +2642,15 @@ Miscellaneous controller provides 3 interface files. If two misc resources (res_
 	  res_a 3
 	  res_b 0
 
+  misc.peak
+        A read-only flat-keyed file shown in all cgroups.  It shows the
+        historical maximum usage of the resources in the cgroup and its
+        children.::
+
+	  $ cat misc.peak
+	  res_a 10
+	  res_b 8
+
   misc.max
         A read-write flat-keyed file shown in the non root cgroups. Allowed
         maximum usage of the resources in the cgroup and its children.::
@@ -2654,6 +2680,11 @@ Miscellaneous controller provides 3 interface files. If two misc resources (res_
 		The number of times the cgroup's resource usage was
 		about to go over the max boundary.
 
+  misc.events.local
+        Similar to misc.events but the fields in the file are local to the
+        cgroup i.e. not hierarchical. The file modified event generated on
+        this file reflects only the local events.
+
 Migration and Ownership
 ~~~~~~~~~~~~~~~~~~~~~~~
 

MAINTAINERS

@@ -5528,6 +5528,7 @@ CONTROL GROUP (CGROUP)
 M:	Tejun Heo <tj@kernel.org>
 M:	Zefan Li <lizefan.x@bytedance.com>
 M:	Johannes Weiner <hannes@cmpxchg.org>
+M:	Michal Koutný <mkoutny@suse.com>
 L:	cgroups@vger.kernel.org
 S:	Maintained
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git

include/linux/cgroup-defs.h

@@ -119,7 +119,12 @@ enum {
 	/*
 	 * Enable hugetlb accounting for the memory controller.
 	 */
-	 CGRP_ROOT_MEMORY_HUGETLB_ACCOUNTING = (1 << 19),
+	CGRP_ROOT_MEMORY_HUGETLB_ACCOUNTING = (1 << 19),
+
+	/*
+	 * Enable legacy local pids.events.
+	 */
+	CGRP_ROOT_PIDS_LOCAL_EVENTS = (1 << 20),
 };
 
 /* cftype->flags */

include/linux/misc_cgroup.h

@@ -9,15 +9,16 @@
 #define _MISC_CGROUP_H_
 
 /**
- * Types of misc cgroup entries supported by the host.
+ * enum misc_res_type - Types of misc cgroup entries supported by the host.
  */
 enum misc_res_type {
 #ifdef CONFIG_KVM_AMD_SEV
-	/* AMD SEV ASIDs resource */
+	/** @MISC_CG_RES_SEV: AMD SEV ASIDs resource */
 	MISC_CG_RES_SEV,
-	/* AMD SEV-ES ASIDs resource */
+	/** @MISC_CG_RES_SEV_ES: AMD SEV-ES ASIDs resource */
 	MISC_CG_RES_SEV_ES,
 #endif
+	/** @MISC_CG_RES_TYPES: count of enum misc_res_type constants */
 	MISC_CG_RES_TYPES
 };
 
@@ -30,13 +31,16 @@ struct misc_cg;
 /**
  * struct misc_res: Per cgroup per misc type resource
  * @max: Maximum limit on the resource.
+ * @watermark: Historical maximum usage of the resource.
  * @usage: Current usage of the resource.
  * @events: Number of times, the resource limit exceeded.
  */
 struct misc_res {
 	u64 max;
+	atomic64_t watermark;
 	atomic64_t usage;
 	atomic64_t events;
+	atomic64_t events_local;
 };
 
 /**
@@ -50,6 +54,8 @@ struct misc_cg {
 
 	/* misc.events */
 	struct cgroup_file events_file;
+	/* misc.events.local */
+	struct cgroup_file events_local_file;
 
 	struct misc_res res[MISC_CG_RES_TYPES];
 };

kernel/cgroup/cgroup.c

@@ -1744,8 +1744,11 @@ static int css_populate_dir(struct cgroup_subsys_state *css)
 			if (cgroup_psi_enabled()) {
 				ret = cgroup_addrm_files(css, cgrp,
 							 cgroup_psi_files, true);
-				if (ret < 0)
+				if (ret < 0) {
+					cgroup_addrm_files(css, cgrp,
+							   cgroup_base_files, false);
 					return ret;
+				}
 			}
 		} else {
 			ret = cgroup_addrm_files(css, cgrp,
@@ -1839,9 +1842,9 @@ int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
 		RCU_INIT_POINTER(scgrp->subsys[ssid], NULL);
 		rcu_assign_pointer(dcgrp->subsys[ssid], css);
 		ss->root = dst_root;
-		css->cgroup = dcgrp;
 
 		spin_lock_irq(&css_set_lock);
+		css->cgroup = dcgrp;
 		WARN_ON(!list_empty(&dcgrp->e_csets[ss->id]));
 		list_for_each_entry_safe(cset, cset_pos, &scgrp->e_csets[ss->id],
 					 e_cset_node[ss->id]) {
@@ -1922,6 +1925,7 @@ enum cgroup2_param {
 	Opt_memory_localevents,
 	Opt_memory_recursiveprot,
 	Opt_memory_hugetlb_accounting,
+	Opt_pids_localevents,
 	nr__cgroup2_params
 };
 
@@ -1931,6 +1935,7 @@ static const struct fs_parameter_spec cgroup2_fs_parameters[] = {
 	fsparam_flag("memory_localevents",	Opt_memory_localevents),
 	fsparam_flag("memory_recursiveprot",	Opt_memory_recursiveprot),
 	fsparam_flag("memory_hugetlb_accounting", Opt_memory_hugetlb_accounting),
+	fsparam_flag("pids_localevents",	Opt_pids_localevents),
 	{}
 };
 
@@ -1960,6 +1965,9 @@ static int cgroup2_parse_param(struct fs_context *fc, struct fs_parameter *param
 	case Opt_memory_hugetlb_accounting:
 		ctx->flags |= CGRP_ROOT_MEMORY_HUGETLB_ACCOUNTING;
 		return 0;
+	case Opt_pids_localevents:
+		ctx->flags |= CGRP_ROOT_PIDS_LOCAL_EVENTS;
+		return 0;
 	}
 	return -EINVAL;
 }
@@ -1989,6 +1997,11 @@ static void apply_cgroup_root_flags(unsigned int root_flags)
 			cgrp_dfl_root.flags |= CGRP_ROOT_MEMORY_HUGETLB_ACCOUNTING;
 		else
 			cgrp_dfl_root.flags &= ~CGRP_ROOT_MEMORY_HUGETLB_ACCOUNTING;
+
+		if (root_flags & CGRP_ROOT_PIDS_LOCAL_EVENTS)
+			cgrp_dfl_root.flags |= CGRP_ROOT_PIDS_LOCAL_EVENTS;
+		else
+			cgrp_dfl_root.flags &= ~CGRP_ROOT_PIDS_LOCAL_EVENTS;
 	}
 }
 
@@ -2004,6 +2017,8 @@ static int cgroup_show_options(struct seq_file *seq, struct kernfs_root *kf_root
 		seq_puts(seq, ",memory_recursiveprot");
 	if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_HUGETLB_ACCOUNTING)
 		seq_puts(seq, ",memory_hugetlb_accounting");
+	if (cgrp_dfl_root.flags & CGRP_ROOT_PIDS_LOCAL_EVENTS)
+		seq_puts(seq, ",pids_localevents");
 	return 0;
 }
 
@@ -6686,8 +6701,10 @@ void cgroup_exit(struct task_struct *tsk)
 	WARN_ON_ONCE(list_empty(&tsk->cg_list));
 	cset = task_css_set(tsk);
 	css_set_move_task(tsk, cset, NULL, false);
-	list_add_tail(&tsk->cg_list, &cset->dying_tasks);
 	cset->nr_tasks--;
+	/* matches the signal->live check in css_task_iter_advance() */
+	if (thread_group_leader(tsk) && atomic_read(&tsk->signal->live))
+		list_add_tail(&tsk->cg_list, &cset->dying_tasks);
 
 	if (dl_task(tsk))
 		dec_dl_tasks_cs(tsk);
@@ -6714,10 +6731,12 @@ void cgroup_release(struct task_struct *task)
 		ss->release(task);
 	} while_each_subsys_mask();
 
-	spin_lock_irq(&css_set_lock);
-	css_set_skip_task_iters(task_css_set(task), task);
-	list_del_init(&task->cg_list);
-	spin_unlock_irq(&css_set_lock);
+	if (!list_empty(&task->cg_list)) {
+		spin_lock_irq(&css_set_lock);
+		css_set_skip_task_iters(task_css_set(task), task);
+		list_del_init(&task->cg_list);
+		spin_unlock_irq(&css_set_lock);
+	}
 }
 
 void cgroup_free(struct task_struct *task)
@@ -7062,7 +7081,8 @@ static ssize_t features_show(struct kobject *kobj, struct kobj_attribute *attr,
 			"favordynmods\n"
 			"memory_localevents\n"
 			"memory_recursiveprot\n"
-			"memory_hugetlb_accounting\n");
+			"memory_hugetlb_accounting\n"
+			"pids_localevents\n");
 }
 static struct kobj_attribute cgroup_features_attr = __ATTR_RO(features);