Re: [PATCH] sched: fix possible divide by zero in avg_atom calculation

[Peter Zijlstra]

On Sat, Jun 14, 2014 at 03:00:09PM +0200, Mateusz Guzik wrote:
> proc_sched_show_task does:
> if (nr_switches)
> 	do_div(avg_atom, nr_switches);
> 
> nr_switches is unsigned long and do_div truncates it to 32 bits, which
> means it can test non-zero on e.g. x86-64 and be truncated to zero for
> division.
> 
> Fix the problem by using div64_ul instead.
> 
> As a side effect calculations of avg_atom for big nr_switches are now correct.
> 
> Signed-off-by: Mateusz Guzik <mguzik@xxxxxxxxxx>

Thanks.

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