diff options
| author | Mateusz Guzik <mguzik@redhat.com> | 2014-06-14 15:00:09 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-07-28 08:00:07 -0700 |
| commit | 4aba6e36347232a9e0cc2e9c8daf42a6bdcdad66 (patch) | |
| tree | 03c2e9855259825ef33630581d37047525378e31 /kernel | |
| parent | e6be7d3115436b2527c60973c901ec3a7c6afe15 (diff) | |
| download | lwn-4aba6e36347232a9e0cc2e9c8daf42a6bdcdad66.tar.gz lwn-4aba6e36347232a9e0cc2e9c8daf42a6bdcdad66.zip | |
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>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/debug.c | 2 |
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; |