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-Url: https://git.stricted.de/?a=commitdiff_plain;h=4aba6e36347232a9e0cc2e9c8daf42a6bdcdad66;p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git sched: Fix possible divide by zero in avg_atom() calculation commit b0ab99e7736af88b8ac1b7ae50ea287fffa2badc upstream. 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: Linus Torvalds Link: http://lkml.kernel.org/r/1402750809-31991-1-git-send-email-mguzik@redhat.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index e745a1548367..701b6c8a4b12 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -551,7 +551,7 @@ 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;