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cgroups: add an owner to the mm_struct

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Remove 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.

After the thread group leader exits, it's moved to init_css_state by
cgroup_exit(), thus all future charges from runnings threads would be
redirected to the init_css_set's subsystem.

Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Pavel Emelianov <xemul@openvz.org>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Sudhir Kumar <skumar@linux.vnet.ibm.com>
Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Cc: Hirokazu Takahashi <taka@valinux.co.jp>
Cc: David Rientjes <rientjes@google.com>,
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Reviewed-by: Paul Menage <menage@google.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Balbir Singh
2008-04-29 01:00:16 -07:00
committed by Linus Torvalds
parent 29486df325
commit cf475ad28a
11 changed files with 169 additions and 41 deletions
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30
kernel/cgroup.c
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@@ -119,6 +119,7 @@ static int root_count;
* be called.
*/
static int need_forkexit_callback;
static int need_mm_owner_callback __read_mostly;
/* convenient tests for these bits */
inline int cgroup_is_removed(const struct cgroup *cgrp)
@@ -2498,6 +2499,7 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
init_css_set.subsys[ss->subsys_id] = dummytop->subsys[ss->subsys_id];
need_forkexit_callback |= ss->fork || ss->exit;
need_mm_owner_callback |= !!ss->mm_owner_changed;
/* At system boot, before all subsystems have been
* registered, no tasks have been forked, so we don't
@@ -2748,6 +2750,34 @@ void cgroup_fork_callbacks(struct task_struct *child)
}
}
#ifdef CONFIG_MM_OWNER
/**
* cgroup_mm_owner_callbacks - run callbacks when the mm->owner changes
* @p: the new owner
*
* Called on every change to mm->owner. mm_init_owner() does not
* invoke this routine, since it assigns the mm->owner the first time
* and does not change it.
*/
void cgroup_mm_owner_callbacks(struct task_struct *old, struct task_struct *new)
{
struct cgroup *oldcgrp, *newcgrp;
if (need_mm_owner_callback) {
int i;
for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
struct cgroup_subsys *ss = subsys[i];
oldcgrp = task_cgroup(old, ss->subsys_id);
newcgrp = task_cgroup(new, ss->subsys_id);
if (oldcgrp == newcgrp)
continue;
if (ss->mm_owner_changed)
ss->mm_owner_changed(ss, oldcgrp, newcgrp);
}
}
}
#endif /* CONFIG_MM_OWNER */
/**
* cgroup_post_fork - called on a new task after adding it to the task list
* @child: the task in question