Commit 6f9d71c9 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'for-4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 

Pull cgroup updates from Tejun Heo:

 - Waiman's cgroup2 cpuset support has been finally merged closing one
   of the last remaining feature gaps.

 - cgroup.procs could show non-leader threads when cgroup2 threaded mode
   was used in certain ways. I forgot to push the fix during the last
   cycle.

 - A patch to fix mount option parsing when all mount options have been
   consumed by someone else (LSM).

 - cgroup_no_v1 boot param can now block named cgroup1 hierarchies too.

* 'for-4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: Add named hierarchy disabling to cgroup_no_v1 boot param
  cgroup: fix parsing empty mount option string
  cpuset: Remove set but not used variable 'cs'
  cgroup: fix CSS_TASK_ITER_PROCS
  cgroup: Add .__DEBUG__. prefix to debug file names
  cpuset: Minor cgroup2 interface updates
  cpuset: Expose cpuset.cpus.subpartitions with cgroup_debug
  cpuset: Add documentation about the new "cpuset.sched.partition" flag
  cpuset: Use descriptive text when reading/writing cpuset.sched.partition
  cpuset: Expose cpus.effective and mems.effective on cgroup v2 root
  cpuset: Make generate_sched_domains() work with partition
  cpuset: Make CPU hotplug work with partition
  cpuset: Track cpusets that use parent's effective_cpus
  cpuset: Add an error state to cpuset.sched.partition
  cpuset: Add new v2 cpuset.sched.partition flag
  cpuset: Simply allocation and freeing of cpumasks
  cpuset: Define data structures to support scheduling partition
  cpuset: Enable cpuset controller in default hierarchy
  cgroup: remove unnecessary unlikely()
parents 55db91fb 3fc9c12d

Documentation/admin-guide/cgroup-v2.rst

+177 −5
Original line number Diff line number Diff line
@@ -56,11 +56,13 @@ v1 is available under Documentation/cgroup-v1/. 
         5-3-3-2. IO Latency Interface Files

     5-4. PID

       5-4-1. PID Interface Files

     5-5. Device

     5-6. RDMA

       5-6-1. RDMA Interface Files

     5-7. Misc

       5-7-1. perf_event

     5-5. Cpuset

       5.5-1. Cpuset Interface Files

     5-6. Device

     5-7. RDMA

       5-7-1. RDMA Interface Files

     5-8. Misc

       5-8-1. perf_event

     5-N. Non-normative information

       5-N-1. CPU controller root cgroup process behaviour

       5-N-2. IO controller root cgroup process behaviour
@@ -1610,6 +1612,176 @@ through fork() or clone(). These will return -EAGAIN if the creation 
of a new process would cause a cgroup policy to be violated.





Cpuset

------



The "cpuset" controller provides a mechanism for constraining

the CPU and memory node placement of tasks to only the resources

specified in the cpuset interface files in a task's current cgroup.

This is especially valuable on large NUMA systems where placing jobs

on properly sized subsets of the systems with careful processor and

memory placement to reduce cross-node memory access and contention

can improve overall system performance.



The "cpuset" controller is hierarchical.  That means the controller

cannot use CPUs or memory nodes not allowed in its parent.





Cpuset Interface Files

~~~~~~~~~~~~~~~~~~~~~~



  cpuset.cpus

	A read-write multiple values file which exists on non-root

	cpuset-enabled cgroups.



	It lists the requested CPUs to be used by tasks within this

	cgroup.  The actual list of CPUs to be granted, however, is

	subjected to constraints imposed by its parent and can differ

	from the requested CPUs.



	The CPU numbers are comma-separated numbers or ranges.

	For example:



	  # cat cpuset.cpus

	  0-4,6,8-10



	An empty value indicates that the cgroup is using the same

	setting as the nearest cgroup ancestor with a non-empty

	"cpuset.cpus" or all the available CPUs if none is found.



	The value of "cpuset.cpus" stays constant until the next update

	and won't be affected by any CPU hotplug events.



  cpuset.cpus.effective

	A read-only multiple values file which exists on all

	cpuset-enabled cgroups.



	It lists the onlined CPUs that are actually granted to this

	cgroup by its parent.  These CPUs are allowed to be used by

	tasks within the current cgroup.



	If "cpuset.cpus" is empty, the "cpuset.cpus.effective" file shows

	all the CPUs from the parent cgroup that can be available to

	be used by this cgroup.  Otherwise, it should be a subset of

	"cpuset.cpus" unless none of the CPUs listed in "cpuset.cpus"

	can be granted.  In this case, it will be treated just like an

	empty "cpuset.cpus".



	Its value will be affected by CPU hotplug events.



  cpuset.mems

	A read-write multiple values file which exists on non-root

	cpuset-enabled cgroups.



	It lists the requested memory nodes to be used by tasks within

	this cgroup.  The actual list of memory nodes granted, however,

	is subjected to constraints imposed by its parent and can differ

	from the requested memory nodes.



	The memory node numbers are comma-separated numbers or ranges.

	For example:



	  # cat cpuset.mems

	  0-1,3



	An empty value indicates that the cgroup is using the same

	setting as the nearest cgroup ancestor with a non-empty

	"cpuset.mems" or all the available memory nodes if none

	is found.



	The value of "cpuset.mems" stays constant until the next update

	and won't be affected by any memory nodes hotplug events.



  cpuset.mems.effective

	A read-only multiple values file which exists on all

	cpuset-enabled cgroups.



	It lists the onlined memory nodes that are actually granted to

	this cgroup by its parent. These memory nodes are allowed to

	be used by tasks within the current cgroup.



	If "cpuset.mems" is empty, it shows all the memory nodes from the

	parent cgroup that will be available to be used by this cgroup.

	Otherwise, it should be a subset of "cpuset.mems" unless none of

	the memory nodes listed in "cpuset.mems" can be granted.  In this

	case, it will be treated just like an empty "cpuset.mems".



	Its value will be affected by memory nodes hotplug events.



  cpuset.cpus.partition

	A read-write single value file which exists on non-root

	cpuset-enabled cgroups.  This flag is owned by the parent cgroup

	and is not delegatable.



        It accepts only the following input values when written to.



        "root"   - a paritition root

        "member" - a non-root member of a partition



	When set to be a partition root, the current cgroup is the

	root of a new partition or scheduling domain that comprises

	itself and all its descendants except those that are separate

	partition roots themselves and their descendants.  The root

	cgroup is always a partition root.



	There are constraints on where a partition root can be set.

	It can only be set in a cgroup if all the following conditions

	are true.



	1) The "cpuset.cpus" is not empty and the list of CPUs are

	   exclusive, i.e. they are not shared by any of its siblings.

	2) The parent cgroup is a partition root.

	3) The "cpuset.cpus" is also a proper subset of the parent's

	   "cpuset.cpus.effective".

	4) There is no child cgroups with cpuset enabled.  This is for

	   eliminating corner cases that have to be handled if such a

	   condition is allowed.



	Setting it to partition root will take the CPUs away from the

	effective CPUs of the parent cgroup.  Once it is set, this

	file cannot be reverted back to "member" if there are any child

	cgroups with cpuset enabled.



	A parent partition cannot distribute all its CPUs to its

	child partitions.  There must be at least one cpu left in the

	parent partition.



	Once becoming a partition root, changes to "cpuset.cpus" is

	generally allowed as long as the first condition above is true,

	the change will not take away all the CPUs from the parent

	partition and the new "cpuset.cpus" value is a superset of its

	children's "cpuset.cpus" values.



	Sometimes, external factors like changes to ancestors'

	"cpuset.cpus" or cpu hotplug can cause the state of the partition

	root to change.  On read, the "cpuset.sched.partition" file

	can show the following values.



	"member"       Non-root member of a partition

	"root"         Partition root

	"root invalid" Invalid partition root



	It is a partition root if the first 2 partition root conditions

	above are true and at least one CPU from "cpuset.cpus" is

	granted by the parent cgroup.



	A partition root can become invalid if none of CPUs requested

	in "cpuset.cpus" can be granted by the parent cgroup or the

	parent cgroup is no longer a partition root itself.  In this

	case, it is not a real partition even though the restriction

	of the first partition root condition above will still apply.

	The cpu affinity of all the tasks in the cgroup will then be

	associated with CPUs in the nearest ancestor partition.



	An invalid partition root can be transitioned back to a

	real partition root if at least one of the requested CPUs

	can now be granted by its parent.  In this case, the cpu

	affinity of all the tasks in the formerly invalid partition

	will be associated to the CPUs of the newly formed partition.

	Changing the partition state of an invalid partition root to

	"member" is always allowed even if child cpusets are present.





Device controller

-----------------

Documentation/admin-guide/kernel-parameters.txt

+6 −2
Original line number Diff line number Diff line
@@ -486,10 +486,14 @@ 
			cut the overhead, others just disable the usage. So

			only cgroup_disable=memory is actually worthy}



	cgroup_no_v1=	[KNL] Disable one, multiple, all cgroup controllers in v1

			Format: { controller[,controller...] | "all" }

	cgroup_no_v1=	[KNL] Disable cgroup controllers and named hierarchies in v1

			Format: { { controller | "all" | "named" }

			          [,{ controller | "all" | "named" }...] }

			Like cgroup_disable, but only applies to cgroup v1;

			the blacklisted controllers remain available in cgroup2.

			"all" blacklists all controllers and "named" disables

			named mounts. Specifying both "all" and "named" disables

			all v1 hierarchies.



	cgroup.memory=	[KNL] Pass options to the cgroup memory controller.

			Format: <string>

include/linux/cgroup-defs.h

+1 −0
Original line number Diff line number Diff line
@@ -92,6 +92,7 @@ enum { 


	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 */

kernel/cgroup/cgroup-internal.h

+2 −0
Original line number Diff line number Diff line
@@ -11,6 +11,8 @@ 
#define TRACE_CGROUP_PATH_LEN 1024

extern spinlock_t trace_cgroup_path_lock;

extern char trace_cgroup_path[TRACE_CGROUP_PATH_LEN];

extern bool cgroup_debug;

extern void __init enable_debug_cgroup(void);



/*

 * cgroup_path() takes a spin lock. It is good practice not to take

kernel/cgroup/cgroup-v1.c

+13 −1
Original line number Diff line number Diff line
@@ -27,6 +27,9 @@ 
/* Controllers blocked by the commandline in v1 */

static u16 cgroup_no_v1_mask;



/* disable named v1 mounts */

static bool cgroup_no_v1_named;



/*

 * pidlist destructions need to be flushed on cgroup destruction.  Use a

 * separate workqueue as flush domain.
@@ -963,6 +966,10 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) 
		}

		if (!strncmp(token, "name=", 5)) {

			const char *name = token + 5;



			/* blocked by boot param? */

			if (cgroup_no_v1_named)

				return -ENOENT;

			/* Can't specify an empty name */

			if (!strlen(name))

				return -EINVAL;
@@ -1292,7 +1299,12 @@ static int __init cgroup_no_v1(char *str) 


		if (!strcmp(token, "all")) {

			cgroup_no_v1_mask = U16_MAX;

			break;

			continue;

		}



		if (!strcmp(token, "named")) {

			cgroup_no_v1_named = true;

			continue;

		}



		for_each_subsys(ss, i) {

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