linux-toradex.git/kernel/cgroup.c, branch v2.6.25.20

cgroups: remove node_ prefix_from ns subsystem

2008-06-09T18:27:01+00:00

upstream commit: 5c02b575780d0d785815a1e7b79a98edddee895a

This is a slight change in the namespace cgroup subsystem api.

The change is that previously when cgroup_clone() was called (currently
only from the unshare path in ns_proxy cgroup, you'd get a new group named
"node_$pid" whereas now you'll get a group named after just your pid.)

The only users who would notice it are those who are using the ns_proxy
cgroup subsystem to auto-create cgroups when namespaces are unshared -
something of an experimental feature, which I think really needs more
complete container/namespace support in order to be useful.  I suspect the
only users are Cedric and Serge, or maybe a few others on
containers@lists.linux-foundation.org.  And in fact it would only be
noticed by the users who make the assumption about how the name is
generated, rather than getting it from the /proc//cgroups file for
the process in question.

Whether the change is actually needed or not I'm fairly agnostic on, but I
guess it is more elegant to just use the pid as the new group name rather
than adding a fairly arbitrary "node_" prefix on the front.

[menage@google.com: provided changelog]
Signed-off-by: Cedric Le Goater 
Cc: "Paul Menage" 
Cc: "Serge E. Hallyn" 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Chris Wright

cgroup: fix a race condition in manipulating tsk->cg_list

2008-05-01T21:44:33+00:00

commit: 0e04388f0189fa1f6812a8e1cb6172136eada87e

When I ran a test program to fork mass processes and at the same time
'cat /cgroup/tasks', I got the following oops:

  ------------[ cut here ]------------
  kernel BUG at lib/list_debug.c:72!
  invalid opcode: 0000 [#1] SMP
  Pid: 4178, comm: a.out Not tainted (2.6.25-rc9 #72)
  ...
  Call Trace:
   [] ? cgroup_exit+0x55/0x94
   [] ? do_exit+0x217/0x5ba
   [] ? do_group_exit+0.65/0x7c
   [] ? sys_exit_group+0xf/0x11
   [] ? syscall_call+0x7/0xb
   [] ? init_cyrix+0x2fa/0x479
  ...
  EIP: [] list_del+0x35/0x53 SS:ESP 0068:ebc7df4
  ---[ end trace caffb7332252612b ]---
  Fixing recursive fault but reboot is needed!

After digging into the code and debugging, I finlly found out a race
situation:

				do_exit()
				  ->cgroup_exit()
				    ->if (!list_empty(&tsk->cg_list))
				        list_del(&tsk->cg_list);

  cgroup_iter_start()
    ->cgroup_enable_task_cg_list()
      ->list_add(&tsk->cg_list, ..);

In this case the list won't be deleted though the process has exited.

We got two bug reports in the past, which seem to be the same bug as
this one:
	http://lkml.org/lkml/2008/3/5/332
	http://lkml.org/lkml/2007/10/17/224

Actually sometimes I got oops on list_del, sometimes oops on list_add.
And I can change my test program a bit to trigger other oops.

The patch has been tested both on x86_32 and x86_64.

Signed-off-by: Li Zefan 
Acked-by: Paul Menage 
Cc: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

cgroups: include hierarchy ids in /proc//cgroup

2008-04-11T15:06:43+00:00

Extend the /proc//cgroup file to include the appropriate hierarchy ID on
each line.

Currently this ID isn't really needed since a hierarchy can be completely
identified by the set of subsystems bound to it, but this is likely to change
in the near future in order to support stateless subsystems and
merging/rebinding of subsystems.  Getting this change into 2.6.25 reduces the
need for an API change later.

Signed-off-by: Paul Menage 
Cc: Balbir Singh 
Cc: Pavel Emelyanov 
Cc: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroups: add cgroup support for enabling controllers at boot time

2008-04-04T21:46:26+00:00

The effects of cgroup_disable=foo are:

- foo isn't auto-mounted if you mount all cgroups in a single hierarchy
- foo isn't visible as an individually mountable subsystem

As a result there will only ever be one call to foo->create(), at init time;
all processes will stay in this group, and the group will never be mounted on
a visible hierarchy.  Any additional effects (e.g.  not allocating metadata)
are up to the foo subsystem.

This doesn't handle early_init subsystems (their "disabled" bit isn't set be,
but it could easily be extended to do so if any of the early_init systems
wanted it - I think it would just involve some nastier parameter processing
since it would occur before the command-line argument parser had been run.

Hugh said:

  Ballpark figures, I'm trying to get this question out rather than
  processing the exact numbers: CONFIG_CGROUP_MEM_RES_CTLR adds 15% overhead
  to the affected paths, booting with cgroup_disable=memory cuts that back to
  1% overhead (due to slightly bigger struct page).

  I'm no expert on distros, they may have no interest whatever in
  CONFIG_CGROUP_MEM_RES_CTLR=y; and the rest of us can easily build with or
  without it, or apply the cgroup_disable=memory patches.

Unix bench's execl test result on x86_64 was

== just after boot without mounting any cgroup fs.==
mem_cgorup=off : Execl Throughput       43.0     3150.1      732.6
mem_cgroup=on  : Execl Throughput       43.0     2932.6      682.0
==

[lizf@cn.fujitsu.com: fix boot option parsing]
Signed-off-by: Balbir Singh 
Cc: Paul Menage 
Cc: Balbir Singh 
Cc: Pavel Emelyanov 
Cc: KAMEZAWA Hiroyuki 
Cc: Hugh Dickins 
Cc: Sudhir Kumar 
Cc: YAMAMOTO Takashi 
Cc: David Rientjes 
Signed-off-by: Li Zefan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

NULL noise: fs/, mm/, kernel/*

2008-03-30T21:18:41+00:00

Signed-off-by: Al Viro 
Signed-off-by: Linus Torvalds

cgroup: fix default notify_on_release setting

2008-03-05T00:35:09+00:00

The documentation says the default value of notify_on_release of a child
cgroup is inherited from its parent, which is reasonable, but the
implementation just sets the flag disabled.

Signed-off-by: Li Zefan 
Acked-by: Paul Menage 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroup: remove dead code in cgroup_get_rootdir()

2008-02-24T01:13:25+00:00

Signed-off-by: Li Zefan 
Acked-by: Paul Menage 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroup: remove duplicate code in find_css_set()

2008-02-24T01:13:25+00:00

The list head res->tasks gets initialized twice in find_css_set().

Signed-off-by: Li Zefan 
Acked-by: Paul Menage 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroup: fix subsys bitops

2008-02-24T01:13:24+00:00

Cgroup uses unsigned long for subsys bitops, not unsigned long long.

Signed-off-by: Li Zefan 
Acked-by: Paul Menage 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroup: fix memory leak in cgroup_get_sb()

2008-02-24T01:13:24+00:00

opts.release_agent is not kfree()ed in all necessary places.

Signed-off-by: Li Zefan 
Acked-by: Paul Menage 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

linux-toradex.git/kernel/cgroup.c, branch v2.6.25.20

cgroups: remove node_ prefix_from ns subsystem

cgroup: fix a race condition in manipulating tsk->cg_list

cgroups: include hierarchy ids in /proc//cgroup

cgroups: add cgroup support for enabling controllers at boot time

NULL noise: fs/*, mm/*, kernel/*

cgroup: fix default notify_on_release setting

cgroup: remove dead code in cgroup_get_rootdir()

cgroup: remove duplicate code in find_css_set()

cgroup: fix subsys bitops

cgroup: fix memory leak in cgroup_get_sb()

NULL noise: fs/, mm/, kernel/*