linux-stable.git/include/linux/cgroup-defs.h, branch v4.12.3

cgroup: Prevent kill_css() from being called more than once

2017-05-17T20:58:32+00:00

The kill_css() function may be called more than once under the condition
that the css was killed but not physically removed yet followed by the
removal of the cgroup that is hosting the css. This patch prevents any
harmm from being done when that happens.

Signed-off-by: Waiman Long 
Signed-off-by: Tejun Heo 
Cc: stable@vger.kernel.org # v4.5+

cgroup: move cgroup_subsys_state parent field for cache locality

2017-04-11T00:06:17+00:00

Various structures embed a struct cgroup_subsys_state, typically at
the top of the containing structure.  It is common for code that
accesses the structures to perform operations that iterate over the
chain of parent css pointers, also accessing data in each containing
structure.  In particular, struct cpuacct is used by fairly hot code
paths in the scheduler such as cpuacct_charge().

Move the parent css pointer field to the end of the structure to
increase the chances of residing in the same cache line as the data
from the containing structure.

Signed-off-by: Todd Poynor 
Signed-off-by: Tejun Heo

kernel: convert css_set.refcount from atomic_t to refcount_t

2017-03-08T22:46:03+00:00

refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: Elena Reshetova 
Signed-off-by: Hans Liljestrand 
Signed-off-by: Kees Cook 
Signed-off-by: David Windsor 
Signed-off-by: Tejun Heo

sched/headers, cgroups: Remove the threadgroup_change_*() wrappery

2017-03-02T07:42:25+00:00

threadgroup_change_begin()/end() is a pointless wrapper around
cgroup_threadgroup_change_begin()/end(), minus a might_sleep()
in the !CONFIG_CGROUPS=y case.

Remove the wrappery, move the might_sleep() (the down_read()
already has a might_sleep() check).

This debloats  a bit and simplifies this API.

Update all call sites.

No change in functionality.

Acked-by: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

cgroup: reorder css_set fields

2016-12-27T19:49:05+00:00

Reorder css_set fields so that they're roughly in the order of how hot
they are.  The rough order is

1. the actual csses
2. reference counter and the default cgroup pointer.
3. task lists and iterations
4. fields used during merge including css_set lookup
5. the rest

Signed-off-by: Tejun Heo 
Acked-by: Acked-by: Zefan Li

cgroup add cftype->open/release() callbacks

2016-12-27T19:49:03+00:00

Pipe the newly added kernfs->open/release() callbacks through cftype.
While at it, as cleanup operations now can be performed from
->release() instead of ->seq_stop(), make the latter optional.

Signed-off-by: Tejun Heo 
Acked-by: Acked-by: Zefan Li

cgroup: add support for eBPF programs

2016-11-25T21:25:52+00:00

This patch adds two sets of eBPF program pointers to struct cgroup.
One for such that are directly pinned to a cgroup, and one for such
that are effective for it.

To illustrate the logic behind that, assume the following example
cgroup hierarchy.

  A - B - C
        \ D - E

If only B has a program attached, it will be effective for B, C, D
and E. If D then attaches a program itself, that will be effective for
both D and E, and the program in B will only affect B and C. Only one
program of a given type is effective for a cgroup.

Attaching and detaching programs will be done through the bpf(2)
syscall. For now, ingress and egress inet socket filtering are the
only supported use-cases.

Signed-off-by: Daniel Mack 
Acked-by: Alexei Starovoitov 
Signed-off-by: David S. Miller

cgroup, cpuset: replace cpuset_post_attach_flush() with cgroup_subsys->post_attach callback

2016-04-25T19:45:14+00:00

Since e93ad19d0564 ("cpuset: make mm migration asynchronous"), cpuset
kicks off asynchronous NUMA node migration if necessary during task
migration and flushes it from cpuset_post_attach_flush() which is
called at the end of __cgroup_procs_write().  This is to avoid
performing migration with cgroup_threadgroup_rwsem write-locked which
can lead to deadlock through dependency on kworker creation.

memcg has a similar issue with charge moving, so let's convert it to
an official callback rather than the current one-off cpuset specific
function.  This patch adds cgroup_subsys->post_attach callback and
makes cpuset register cpuset_post_attach_flush() as its ->post_attach.

The conversion is mostly one-to-one except that the new callback is
called under cgroup_mutex.  This is to guarantee that no other
migration operations are started before ->post_attach callbacks are
finished.  cgroup_mutex is one of the outermost mutex in the system
and has never been and shouldn't be a problem.  We can add specialized
synchronization around __cgroup_procs_write() but I don't think
there's any noticeable benefit.

Signed-off-by: Tejun Heo 
Cc: Li Zefan 
Cc: Johannes Weiner 
Cc: Michal Hocko 
Cc:  # 4.4+ prerequisite for the next patch

cgroup: ignore css_sets associated with dead cgroups during migration

2016-03-16T20:31:46+00:00

Before 2e91fa7f6d45 ("cgroup: keep zombies associated with their
original cgroups"), all dead tasks were associated with init_css_set.
If a zombie task is requested for migration, while migration prep
operations would still be performed on init_css_set, the actual
migration would ignore zombie tasks.  As init_css_set is always valid,
this worked fine.

However, after 2e91fa7f6d45, zombie tasks stay with the css_set it was
associated with at the time of death.  Let's say a task T associated
with cgroup A on hierarchy H-1 and cgroup B on hiearchy H-2.  After T
becomes a zombie, it would still remain associated with A and B.  If A
only contains zombie tasks, it can be removed.  On removal, A gets
marked offline but stays pinned until all zombies are drained.  At
this point, if migration is initiated on T to a cgroup C on hierarchy
H-2, migration path would try to prepare T's css_set for migration and
trigger the following.

 WARNING: CPU: 0 PID: 1576 at kernel/cgroup.c:474 cgroup_get+0x121/0x160()
 CPU: 0 PID: 1576 Comm: bash Not tainted 4.4.0-work+ #289
 ...
 Call Trace:
  [] dump_stack+0x4e/0x82
  [] warn_slowpath_common+0x78/0xb0
  [] warn_slowpath_null+0x15/0x20
  [] cgroup_get+0x121/0x160
  [] link_css_set+0x7b/0x90
  [] find_css_set+0x3bc/0x5e0
  [] cgroup_migrate_prepare_dst+0x89/0x1f0
  [] cgroup_attach_task+0x157/0x230
  [] __cgroup_procs_write+0x2b7/0x470
  [] cgroup_tasks_write+0xc/0x10
  [] cgroup_file_write+0x30/0x1b0
  [] kernfs_fop_write+0x13c/0x180
  [] __vfs_write+0x23/0xe0
  [] vfs_write+0xa4/0x1a0
  [] SyS_write+0x44/0xa0
  [] entry_SYSCALL_64_fastpath+0x12/0x6f

It doesn't make sense to prepare migration for css_sets pointing to
dead cgroups as they are guaranteed to contain only zombies which are
ignored later during migration.  This patch makes cgroup destruction
path mark all affected css_sets as dead and updates the migration path
to ignore them during preparation.

Signed-off-by: Tejun Heo 
Fixes: 2e91fa7f6d45 ("cgroup: keep zombies associated with their original cgroups")
Cc: stable@vger.kernel.org # v4.4+

cgroup: implement cgroup_subsys->implicit_on_dfl

2016-03-08T16:51:26+00:00

Some controllers, perf_event for now and possibly freezer in the
future, don't really make sense to control explicitly through
"cgroup.subtree_control".  For example, the primary role of perf_event
is identifying the cgroups of tasks; however, because the controller
also keeps a small amount of state per cgroup, it can't be replaced
with simple cgroup membership tests.

This patch implements cgroup_subsys->implicit_on_dfl flag.  When set,
the controller is implicitly enabled on all cgroups on the v2
hierarchy so that utility type controllers such as perf_event can be
enabled and function transparently.

An implicit controller doesn't show up in "cgroup.controllers" or
"cgroup.subtree_control", is exempt from no internal process rule and
can be stolen from the default hierarchy even if there are non-root
csses.

v2: Reimplemented on top of the recent updates to css handling and
    subsystem rebinding.  Rebinding implicit subsystems is now a
    simple matter of exempting it from the busy subsystem check.

Signed-off-by: Tejun Heo