> On Wed, Jun 16, 2010 at 08:32:08PM +0900, KOSAKI Motohiro wrote:
quoted text
> > 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. 

This patch changed child selection logic. select_bad_process() doesn't
check victim's child. IOW, this is necessary when all 1-3.



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