linux-kernel - Re: 2.6.28, limiting cpu time doesn't work

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Message-ID: <20090322231111.GA21775@redhat.com>
Date:	Mon, 23 Mar 2009 00:11:11 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Peter Lojkin <ia6432@...ox.ru>
Cc:	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>, rjw@...k.pl
Subject: Re: 2.6.28, limiting cpu time doesn't work

On 03/23, Peter Lojkin wrote:
>
> Oleg Nesterov wrote:
>
> > Found this message on http://bugzilla.kernel.org/show_bug.cgi?id=12911 ...
> >
> > I _think_ posix_cpu_timers_init_group() is not right, it should copy
> > cputime_expires->prof_exp.
> >
> > Peter, any chance you can test the (uncompiled/untested) patch below?
>
> yes, with this patch 2.6.28.8 works as expected, thank you!

Great, thanks!

> if you need to test any more patches on the subject i'm ready to do it.
> regression test system for our project depends on ability to limit cpu time,
> so it's major problem for us...

I am not sure what should we do, this needs more discussion.

Probably the most simple patch for -stable and 2.6.29 is below.
(with this patch we don't even need update_rlimit_cpu(), afaics).

Oleg.

--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -1263,7 +1263,8 @@ static inline int fastpath_timer_check(s
 		if (task_cputime_expired(&group_sample, &sig->cputime_expires))
 			return 1;
 	}
-	return 0;
+
+	return sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY;
 }
 
 /*

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