From: Mateusz Guzik Date: Sat, 14 Jun 2014 13:00:09 +0000 (+0200) Subject: sched: Fix possible divide by zero in avg_atom() calculation X-Git-Tag: v4.14-rc1~7206^2 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=b0ab99e7736af88b8ac1b7ae50ea287fffa2badc;p=platform%2Fkernel%2Flinux-rpi.git 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 Signed-off-by: Peter Zijlstra Cc: stable@vger.kernel.org Cc: Linus Torvalds Link: http://lkml.kernel.org/r/1402750809-31991-1-git-send-email-mguzik@redhat.com Signed-off-by: Ingo Molnar --- diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 695f9773bb60..627b3c34b821 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;