Messages in this thread | | | Date | Tue, 01 Apr 2008 11:53:47 +0530 | From | Balbir Singh <> | Subject | Re: [RFC][-mm] Add an owner to the mm_struct (v3) |
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Paul Menage wrote: > On Mon, Mar 31, 2008 at 10:43 PM, Balbir Singh > <balbir@linux.vnet.ibm.com> wrote: >> -static struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p) >> +struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p) >> { >> return container_of(task_subsys_state(p, mem_cgroup_subsys_id), >> struct mem_cgroup, css); >> } > > This should probably be inlined in the header file if it's needed > outside this file.
I thought about it, but that also means we need to export struct mem_cgroup into the header file
>> +static inline void mm_fork_init_owner(struct task_struct *p) >> +{ >> +} > > I think this is stale. >
Yes, it is stale now :)
>> + >> +void mm_update_next_owner(struct mm_struct *mm) >> +{ >> + struct task_struct *c, *g, *p = current; >> + >> + /* >> + * This routine should not be called for init_task >> + */ >> + BUG_ON(p == p->parent); > > I think (as you mentioned earlier) that we need an RCU critical > section in this function, in order for the tasklist traversal to be > safe. > > Maybe also BUG_ON(p != mm->owner) ? >
Yes
>> + list_for_each_entry(c, &p->children, sibling) { >> + if (c->mm && (c->mm == mm)) > > Since mm != NULL, no need to test for c->mm since if it's NULL then c->mm != mm >
OK
>> +assign_new_owner: >> + BUG_ON(c == p); >> + task_lock(c); >> + if (c->mm != mm) { >> + task_unlock(c); >> + goto retry; >> + } >> + mm->owner = c; > > Here we'll want to call vm_cgroup_update_mm_owner(), to adjust the > accounting. (Or if in future we end up with more than a couple of > subsystems that want notification at this time, we'll want to call > cgroup_update_mm_owner() and have it call any interested subsystems. >
I don't think we need to adjust accounting, since only mm->owner is changing and not the cgroup to which the task/mm belongs. Do we really need to notify? I don't want to do any notifications under task_lock().
> Paul
-- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL
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