Re: [patch] oom: thaw threads if oom killed thread is frozen before deferring
From: Oleg Nesterov <oleg@redhat.com>
Date: 2011-09-29 16:41:38
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On 09/29, Michal Hocko wrote:
On Thu 29-09-11 14:05:17, Oleg Nesterov wrote:quoted
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.
quoted hunk ↗ jump to hunk
--- 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. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>