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Subject: Re: [PATCH] sched_fair.c:find_busiest_group(), kernel 2.6.35.7
From: Peter Zijlstra <peterz@infradead.org>
To: Andrew Dickinson <whydna@whydna.net>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>
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Date: Wed, 20 Oct 2010 13:17:27 +0200
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On Wed, 2010-10-20 at 00:20 -0700, Andrew Dickinson wrote:
> This is a patch to fix the corner case where we're crashing with
> divide_error in find_busiest_group (see
> https://bugzilla.kernel.org/show_bug.cgi?id=16991).
> I don't fully understand what the case is that causes sds.total_pwr to
> be zero in find_busiest_group, but this patch guards against the
> divide-by-zero bug.
> 
> I also added safe-guarding around other routines in the scheduler code
> where we're dividing by power; that's more of a just-in-case and I'm
> definitely open for debate on that.

No.. papering over crap like this is not done. In that BZ there's a
number of suggestions of how/where to track down the actual root cause,
but apparently nobody is interested in doing that.

(I can't reproduce so I can't actually do anything about it).