On Tue, Oct 30, 2012 at 1:30 PM, Luigi Semenzato <semenzato@xxxxxxxxxx> wrote:
>
> On Tue, Oct 30, 2012 at 12:12 PM, Luigi Semenzato <semenzato@xxxxxxxxxx> wrote:
>
> > OK, now someone is going to fix this, right? :-)
>
> Actually, there is a very simple fix:
>
> @@ -355,14 +364,6 @@ static struct task_struct
> *select_bad_process(unsigned int *ppoints,
> if (p == current) {
> chosen = p;
> *ppoints = 1000;
> - } else if (!force_kill) {
> - /*
> - * If this task is not being ptraced on exit,
> - * then wait for it to finish before killing
> - * some other task unnecessarily.
> - */
> - if (!(p->group_leader->ptrace & PT_TRACE_EXIT))
> - return ERR_PTR(-1UL);
> }
> }
>
> I'd rather kill some other task unnecessarily than hang! My load
> works fine with this change.
It also appears that we didn't kill any unnecessary tasks either.
It's just a deadlock
exiting process A encounters a page fault and has to allocate some
memory and goes to sleep
process B which is running the OOM Killer blocks on exiting process
and process A blocks forever on memory while process B blocks on A,
and therefore no memory is released
IMO, the fact that we don't do this when the process is being ptraced
also seems to justify that it's a valid thing to do in all cases.
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