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authorMateusz Guzik <mguzik@redhat.com>2014-06-14 15:00:09 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-07-28 08:00:07 -0700
commit4aba6e36347232a9e0cc2e9c8daf42a6bdcdad66 (patch)
tree03c2e9855259825ef33630581d37047525378e31
parente6be7d3115436b2527c60973c901ec3a7c6afe15 (diff)
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 <mguzik@redhat.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1402750809-31991-1-git-send-email-mguzik@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--kernel/sched/debug.c2
1 files changed, 1 insertions, 1 deletions
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;