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| author | Stanislaw Gruszka <sgruszka@redhat.com> | 2013-09-04 15:16:03 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-09-04 16:31:25 +0200 |
| commit | 5a8e01f8fa51f5cbce8f37acc050eb2319d12956 (patch) | |
| tree | 01173781a3b8ea5583cc7d256e8c476c48aab1a9 /crypto | |
| parent | c2e7fcf53c3cb02b4ada1c66a9bc8a4d97d58aba (diff) | |
| download | linux-5a8e01f8fa51f5cbce8f37acc050eb2319d12956.tar.bz2 | |
sched/cputime: Do not scale when utime == 0
scale_stime() silently assumes that stime < rtime, otherwise
when stime == rtime and both values are big enough (operations
on them do not fit in 32 bits), the resulting scaling stime can
be bigger than rtime. In consequence utime = rtime - stime
results in negative value.
User space visible symptoms of the bug are overflowed TIME
values on ps/top, for example:
$ ps aux | grep rcu
root 8 0.0 0.0 0 0 ? S 12:42 0:00 [rcuc/0]
root 9 0.0 0.0 0 0 ? S 12:42 0:00 [rcub/0]
root 10 62422329 0.0 0 0 ? R 12:42 21114581:37 [rcu_preempt]
root 11 0.1 0.0 0 0 ? S 12:42 0:02 [rcuop/0]
root 12 62422329 0.0 0 0 ? S 12:42 21114581:35 [rcuop/1]
root 10 62422329 0.0 0 0 ? R 12:42 21114581:37 [rcu_preempt]
or overflowed utime values read directly from /proc/$PID/stat
Reference:
https://lkml.org/lkml/2013/8/20/259
Reported-and-tested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: stable@vger.kernel.org
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Link: http://lkml.kernel.org/r/20130904131602.GC2564@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'crypto')
0 files changed, 0 insertions, 0 deletions