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Subject[PATCH v2] sched: fix user time incorrectly accounted as system time on 32 bit
We have 32 bit variable overflow possibility when multiply in
task_times() and thread_group_times() functions. If overflow happens
calculated scaled utime value become wrongly small and scaled stime
wrongly big.

Reported here:
https://bugzilla.redhat.com/show_bug.cgi?id=633037
https://bugzilla.kernel.org/show_bug.cgi?id=16559

Reported-by: Michael Chapman <redhat-bugzilla@very.puzzling.org>
Reported-by: Ciriaco Garcia de Celis <sysman@etherpilot.com>
Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@kernel.org> # 2.6.32.19+ (partially) and 2.6.33+
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
---
v1 -> v2
Fix mail recipients.
kernel/sched.c | 8 ++++----
1 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c
index 09b574e..eee9470 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3507,9 +3507,9 @@ void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
rtime = nsecs_to_cputime(p->se.sum_exec_runtime);

if (total) {
- u64 temp;
+ u64 temp = rtime;

- temp = (u64)(rtime * utime);
+ temp *= utime;
do_div(temp, total);
utime = (cputime_t)temp;
} else
@@ -3540,9 +3540,9 @@ void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
rtime = nsecs_to_cputime(cputime.sum_exec_runtime);

if (total) {
- u64 temp;
+ u64 temp = rtime;

- temp = (u64)(rtime * cputime.utime);
+ temp *= cputime.utime;
do_div(temp, total);
utime = (cputime_t)temp;
} else
--
1.7.1


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