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Date: Sat, 14 Jun 2014 15:00:09 +0200 From: Mateusz Guzik <mguzik@...hat.com> To: linux-kernel@...r.kernel.org Cc: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>, stable@...r.kernel.org Subject: [PATCH] sched: fix possible divide by zero in avg_atom calculation 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@...hat.com> Cc: Ingo Molnar <mingo@...hat.com> Cc: Peter Zijlstra <peterz@...radead.org> Cc: stable@...r.kernel.org --- kernel/sched/debug.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 695f977..627b3c3 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -608,7 +608,7 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m) avg_atom = p->se.sum_exec_runtime; if (nr_switches) - do_div(avg_atom, nr_switches); + avg_atom = div64_ul(avg_atom, nr_switches); else avg_atom = -1LL; -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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