Merge branch 'for-4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Each subsystem should:

- add an entry in linux/cgroup_subsys.h

- define a cgroup_subsys object called <name>_subsys

If a subsystem can be compiled as a module, it should also have in its

module initcall a call to cgroup_load_subsys(), and in its exitcall a

call to cgroup_unload_subsys(). It should also set its_subsys.module =

THIS_MODULE in its .c file.

- define a cgroup_subsys object called <name>_cgrp_subsys

Each subsystem may export the following methods. The only mandatory

methods are css_alloc/free. Any others that are null are presumed to

	Only anonymous and swap cache memory is listed as part of 'rss' stat.

	This should not be confused with the true 'resident set size' or the

	amount of physical memory used by the cgroup.

	'rss + file_mapped" will give you resident set size of cgroup.

	'rss + mapped_file" will give you resident set size of cgroup.

	(Note: file and shmem may be shared among other cgroups. In that case,

	 file_mapped is accounted only when the memory cgroup is owner of page

	 mapped_file is accounted only when the memory cgroup is owner of page

	 cache.)

5.3 swappiness

       5-3-2. Writeback

     5-4. PID

       5-4-1. PID Interface Files

     5-5. RDMA

       5-5-1. RDMA Interface Files

     5-6. Misc

       5-6-1. perf_event

     5-5. Device

     5-6. RDMA

       5-6-1. RDMA Interface Files

     5-7. Misc

       5-7-1. 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

   6. Namespace

     6-1. Basics

     6-2. The Root and Views

  exempt from this requirement.

Topology-wise, a cgroup can be in an invalid state.  Please consider

the following toplogy::

the following topology::

  A (threaded domain) - B (threaded) - C (domain, just created)

processes and anonymous resource consumption which can't be associated

with any other cgroups and requires special treatment from most

controllers.  How resource consumption in the root cgroup is governed

is up to each controller.

is up to each controller (for more information on this topic please

refer to the Non-normative information section in the Controllers

chapter).

Note that the restriction doesn't get in the way if there is no

enabled controller in the cgroup's "cgroup.subtree_control".  This is

		reached the limit and allocation was about to fail.

		Depending on context result could be invocation of OOM

		killer and retrying allocation or failing alloction.

		killer and retrying allocation or failing allocation.

		Failed allocation in its turn could be returned into

		userspace as -ENOMEM or siletly ignored in cases like

		userspace as -ENOMEM or silently ignored in cases like

		disk readahead.  For now OOM in memory cgroup kills

		tasks iff shortage has happened inside page fault.

	cgroups.  The default is "max".

	Swap usage hard limit.  If a cgroup's swap usage reaches this

	limit, anonymous meomry of the cgroup will not be swapped out.

	limit, anonymous memory of the cgroup will not be swapped out.

Usage Guidelines

of a new process would cause a cgroup policy to be violated.

Device controller

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

Device controller manages access to device files. It includes both

creation of new device files (using mknod), and access to the

existing device files.

Cgroup v2 device controller has no interface files and is implemented

on top of cgroup BPF. To control access to device files, a user may

create bpf programs of the BPF_CGROUP_DEVICE type and attach them

to cgroups. On an attempt to access a device file, corresponding

BPF programs will be executed, and depending on the return value

the attempt will succeed or fail with -EPERM.

A BPF_CGROUP_DEVICE program takes a pointer to the bpf_cgroup_dev_ctx

structure, which describes the device access attempt: access type

(mknod/read/write) and device (type, major and minor numbers).

If the program returns 0, the attempt fails with -EPERM, otherwise

it succeeds.

An example of BPF_CGROUP_DEVICE program may be found in the kernel

source tree in the tools/testing/selftests/bpf/dev_cgroup.c file.

RDMA

----

moved to a legacy hierarchy after v2 hierarchy is populated.

Non-normative information

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

This section contains information that isn't considered to be a part of

the stable kernel API and so is subject to change.

CPU controller root cgroup process behaviour

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

When distributing CPU cycles in the root cgroup each thread in this

cgroup is treated as if it was hosted in a separate child cgroup of the

root cgroup. This child cgroup weight is dependent on its thread nice

level.

For details of this mapping see sched_prio_to_weight array in

kernel/sched/core.c file (values from this array should be scaled

appropriately so the neutral - nice 0 - value is 100 instead of 1024).

IO controller root cgroup process behaviour

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

Root cgroup processes are hosted in an implicit leaf child node.

When distributing IO resources this implicit child node is taken into

account as if it was a normal child cgroup of the root cgroup with a

weight value of 200.

Namespace

=========

/*

 * Control Group subsystem type.

 * See Documentation/cgroups/cgroups.txt for details

 * See Documentation/cgroup-v1/cgroups.txt for details

 */

struct cgroup_subsys {

	struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css);

size_t strlcpy(char *, const char *, size_t);

#endif

#ifndef __HAVE_ARCH_STRSCPY

ssize_t __must_check strscpy(char *, const char *, size_t);

ssize_t strscpy(char *, const char *, size_t);

#endif

#ifndef __HAVE_ARCH_STRCAT

extern char * strcat(char *, const char *);