Messages in this thread | | | Date | Thu, 29 Sep 2011 18:37:24 +0200 | From | Oleg Nesterov <> | Subject | Re: [patch] oom: thaw threads if oom killed thread is frozen before deferring |
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On 09/29, Michal Hocko wrote: > > On Thu 29-09-11 14:05:17, Oleg Nesterov wrote: > > > But of course this can't help if freeze_task() is called later. > > May be freezable() should check TIF_MEMDIE... > > Wouldn't it be easier to ignore try_to_freeze when fatal signals are > pending in get_signal_to_deliver?
Oh, I don't think so. For what? This doesn't close other races, and in fact the fatal_signal_pending() this patch adds is itself racy, SIGKILL can come in between.
> --- a/kernel/freezer.c > +++ b/kernel/freezer.c > @@ -48,6 +48,11 @@ void refrigerator(void) > current->flags |= PF_FREEZING; > > for (;;) { > + if (fatal_signal_pending(current)) { > + if (freezing(current) || frozen(current)) > + thaw_process(current);
Ah, I didn't mean refrigerator() should check freezing/frozen.
I meant, oom_kill can do this before thaw thaw_process(), afaics this should fix the particular race you described (but not others).
And. It is simply wrong to return from refrigerator() after we set PF_FROZEN, this can fool try_to_freeze_tasks(). Sure, thaw_process() from oom_kill is not nice too, but at least this is the special case, we already have the problem.
Oleg.
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