Changelog v5

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

Remove the hooks for .owner from init_task.h and move it to init/main.c
Changelog v4

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

1. Release rcu_read_lock() after acquiring task_lock(). Also get a reference

   to the task_struct

2. Change cgroup mm_owner_changed callback to callback only if the

   cgroup of old and new task is different and to pass the old and new

   cgroups instead of task pointers

3. Port the patch to 2.6.25-rc8-mm1
Changelog v3

------------
1. Add mm->owner change callbacks using cgroups
This patch removes the mem_cgroup member from mm_struct and instead adds

an owner. This approach was suggested by Paul Menage. The advantage of

this approach is that, once the mm->owner is known, using the subsystem

id, the cgroup can be determined. It also allows several control groups

that are virtually grouped by mm_struct, to exist independent of the memory

controller i.e., without adding mem_cgroup's for each controller,

to mm_struct.
A new config option CONFIG_MM_OWNER is added and the memory resource

controller selects this config option.
This patch also adds cgroup callbacks to notify subsystems when mm->owner

changes. The mm_cgroup_changed callback is called with the task_lock()

of the new task held and is called just prior to changing the mm->owner.
I am indebted to Paul Menage for the several reviews of this patchset

and helping me make it lighter and simpler.
This patch was tested on a powerpc box, it was compiled with both the

MM_OWNER config turned on and off.
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>

---
 fs/exec.c                  |    1

 include/linux/cgroup.h     |   15 ++++++++

 include/linux/init_task.h  |    1

 include/linux/memcontrol.h |   16 +--------

 include/linux/mm_types.h   |    5 +-

 include/linux/sched.h      |   13 +++++++

 init/Kconfig               |   15 ++++++++

 init/main.c                |    1

 kernel/cgroup.c            |   30 +++++++++++++++++

 kernel/exit.c              |   77...
[ message continues ]

Even better, maybe just pass in the relevant cgroup_subsys_state
These get/put calls are now unwanted?
Could you also add comments in mm_need_new_owner(), in particular the

reason for checking for delay_group_leader() ?
Paul

--

Is that better than passing the cgroups? All the callbacks I see usually pass

either task_struct or cgroup. Won't it be better, consistent use of API to pass
Yep, will do
--

	Warm Regards,

	Balbir Singh

	Linux Technology Center

	IBM, ISTL

--

I have a long term plan to try to divorce the subsystems from having

to worry too much about actual control groups where possible.
But I guess that for consistency with the current API, passing in the

cgroup is OK.
Paul

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