Re: [PATCH 3/9] oom: oom_kill_process() doesn't select kthread child

[Minchan Kim <minchan.kim@gmail.com>]

On Wed, Jun 16, 2010 at 08:32:08PM +0900, KOSAKI Motohiro wrote:
> Now, select_bad_process() have PF_KTHREAD check, but oom_kill_process
> doesn't. It mean oom_kill_process() may choose wrong task, especially,
> when the child are using use_mm().
Now oom_kill_process is called by three place. 

1. mem_cgroup_out_of_memory
2. out_of_memory with sysctl_oom_kill_allocating_task
3. out_of_memory with non-sysctl_oom_kill_allocating_task

I think it's no problem in 1 and 3 since select_bad_process already checks
PF_KTHREAD. The problem in in 2. 
So How about put the check before calling oom_kill_process in case of
sysctl_oom_kill_allocating task?

if (sysctl_oom_kill_allocating_task) {
        if (!current->flags & PF_KTHREAD)
                oom_kill_process();
                        
It can remove duplicated PF_KTHREAD check in select_bad_process and
oom_kill_process. 

-- 
Kind regards,
Minchan Kim