Re: [PATCH] mm,oom: fix oom invocation issues

[Roman Gushchin <guro@fb.com>]

On Thu, May 18, 2017 at 11:00:39AM +0200, Michal Hocko wrote:
> On Thu 18-05-17 10:47:29, Michal Hocko wrote:
> > 
> > Hmm, I guess you are right. I haven't realized that pagefault_out_of_memory
> > can race and pick up another victim. For some reason I thought that the
> > page fault would break out on fatal signal pending but we don't do that (we
> > used to in the past). Now that I think about that more we should
> > probably remove out_of_memory out of pagefault_out_of_memory completely.
> > It is racy and it basically doesn't have any allocation context so we
> > might kill a task from a different domain. So can we do this instead?
> > There is a slight risk that somebody might have returned VM_FAULT_OOM
> > without doing an allocation but from my quick look nobody does that
> > currently.
> 
> If this is considered too risky then we can do what Roman was proposing
> and check tsk_is_oom_victim in pagefault_out_of_memory and bail out.

Hi, Michal!

If we consider this approach, I've prepared a separate patch for this problem
(stripped all oom reaper list stuff).

Thanks!