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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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16
kernel/exit.c
View file

@ -642,35 +642,31 @@ retry:
/*
* We found no owner yet mm_users > 1: this implies that we are
* most likely racing with swapoff (try_to_unuse()) or /proc or
* ptrace or page migration (get_task_mm()). Mark owner as NULL,
* so that subsystems can understand the callback and take action.
* ptrace or page migration (get_task_mm()). Mark owner as NULL.
*/
down_write(&mm->mmap_sem);
cgroup_mm_owner_callbacks(mm->owner, NULL);
mm->owner = NULL;
up_write(&mm->mmap_sem);
return;
assign_new_owner:
BUG_ON(c == p);
get_task_struct(c);
read_unlock(&tasklist_lock);
down_write(&mm->mmap_sem);
/*
* The task_lock protects c->mm from changing.
* We always want mm->owner->mm == mm
*/
task_lock(c);
/*
* Delay read_unlock() till we have the task_lock()
* to ensure that c does not slip away underneath us
*/
read_unlock(&tasklist_lock);
if (c->mm != mm) {
task_unlock(c);
up_write(&mm->mmap_sem);
put_task_struct(c);
goto retry;
}
cgroup_mm_owner_callbacks(mm->owner, c);
mm->owner = c;
task_unlock(c);
up_write(&mm->mmap_sem);
put_task_struct(c);
}
#endif /* CONFIG_MM_OWNER */