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mm: remove cgroup_mm_owner_callbacks

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cgroup_mm_owner_callbacks() was brought in to support the memrlimit
controller, but sneaked into mainline ahead of it.  That controller has
now been shelved, and the mm_owner_changed() args were inadequate for it
anyway (they needed an mm pointer instead of a task pointer).

Remove the dead code, and restore mm_update_next_owner() locking to how it
was before: taking mmap_sem there does nothing for memcontrol.c, now the
only user of mm->owner.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Paul Menage <menage@google.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hugh Dickins
2009-01-06 14:39:22 -08:00
committed by Linus Torvalds
parent 39f0dee2d8
commit e5991371ee
3 changed files with 7 additions and 56 deletions
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33
kernel/cgroup.c
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@@ -116,7 +116,6 @@ static int root_count;
* be called.
*/
static int need_forkexit_callback __read_mostly;
static int need_mm_owner_callback __read_mostly;
/* convenient tests for these bits */
inline int cgroup_is_removed(const struct cgroup *cgrp)
@@ -2539,7 +2538,6 @@ 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
@@ -2789,37 +2787,6 @@ 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.
*
* The callbacks are invoked with mmap_sem held in read mode.
*/
void cgroup_mm_owner_callbacks(struct task_struct *old, struct task_struct *new)
{
struct cgroup *oldcgrp, *newcgrp = NULL;
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);
if (new)
newcgrp = task_cgroup(new, ss->subsys_id);
if (oldcgrp == newcgrp)
continue;
if (ss->mm_owner_changed)
ss->mm_owner_changed(ss, oldcgrp, newcgrp, new);
}
}
}
#endif /* CONFIG_MM_OWNER */
/**
* cgroup_post_fork - called on a new task after adding it to the task list
* @child: the task in question