I used memrlimit cgroup at the first time.
May I ask a question about memrlimit cgroup ?
In following
==
static void memrlimit_cgroup_move_task(struct cgroup_subsys *ss,
struct cgroup *cgrp,
struct cgroup *old_cgrp,
struct task_struct *p)
{
struct mm_struct *mm;
struct memrlimit_cgroup *memrcg, *old_memrcg;
<snip>
if (res_counter_charge(&memrcg->as_res, (mm->total_vm << PAGE_SHIFT)))
goto out;
res_counter_uncharge(&old_memrcg->as_res, (mm->total_vm << PAGE_SHIFT));
==
This is a callback for task_attach(). and this never fails.
What happens when the moved task, which move-of-charge fails, exits ?
==
% mkdir /dev/cgroup/memrlimit/group_01
% mkdir /dev/cgroup/memrlimit/group_02
% echo 1G > /dev/cgroup/memrlimit/group_01/memrlimit.limit_in_bytes
% echo 0 > /dev/cgroup/memrlimit/group_02/memrlimit.limit_in_bytes
% echo $$ > /dev/cgroup/memrlimit/group_01/tasks
% echo $$ > /dev/cgroup/memrlimit/group_02/tasks
% exit
== you'll see WARNING ==
I think the charge of the new group goes to minus. right ?
(and old group's charge never goes down.)
I don't think this is "no problem".
What kind of patch is necessary to fix this ?
task_attach() should be able to fail in future ?
I'm sorry if I misunderstand something or this is already in TODO list.
Thanks,
-Kame
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