stime and utime overflow in /proc/stat

[Jochen Eisner]

I'am using Ubuntu Server amd64 10.04

Linux alge 2.6.32-28-server #55-Ubuntu SMP Mon Jan 10 23:57:16 UTC 2011 x86_64 GNU/Linux

The utime counter in /proc/stat is overflowing at a value of roughly 2^32/10, also the stime counter is roughly 2^62 afterwards.

Here i dumped the content of /proc/stat for a process which used >2.1 mil cpu sec every 60 seconds - last correct line:

29630 (main) R 29629 27811 17057 34818 27811 4202496 48883664 0 3 0 214675699 42974 0 0 20 0 24 0 199761349 15510073344 3561325 18446744073709551615 4194304 4423296 140734657761152 140734657757880 4249123 0 0 0 0 18446744073709551615 0 0 17 12 0 0 0 0 0

214675699 and 42974 are correct values of user and system time

60 secs later:

29630 (main) R 29629 27811 17057 34818 27811 4202496 48889323 0 3 0 85858531240 4611685932568856662 0 0 20 0 24 0 199761349 15510749184 3565333 18446744073709551615 4194304 4423296 140734657761152 140734657757880 4251022 0 0 0 0 18446744073709551615 0 0 17 12 0 0 0 0 0

85858531240 and 4611685932568856662 - not so good....

ps or top or htop are showing garbage for usertime afterwards.
_SC_CLK_TCK seems to be 100 on my system.

[Amaury Demol (ubuntu-20-amaury)]

Same problem here.
The /proc/<pid>/stat is
24958 (my_prog) R 2715 24958 2715 34821 24958 4202496 9880 0 12 0 85865547142 4611685932561840760 0 0 20 0 1 0 260208895 82169856 7534 18446744073709551615 4194304 7543765 140733910046816 140733910039880 5147444 0 0 0 0 0 0 0 17 2 0 0 0 0 0
ps aux gives
my_login 24958 305466865 0.7 80244 30136 pts/5 R+ May27 17179869:11 my_prog
uname -a
Linux frpar1lx052 2.6.32-31-generic #61-Ubuntu SMP Fri Apr 8 18:25:51 UTC 2011 x86_64 GNU/Linux

I'm not an expert in kernel but looking at numbers given by Jochen :
2146756990+429740+60000 < 2**31 (why overflow now)
4611685932568856662 + 85858531240 ~ 2**62
I would say that the overflow is rather in the total time (current_time - stating_time)

[Brad Figg (brad-figg)]

This bug is missing log files that will aid in dianosing the problem. From a terminal window please run:

apport-collect 747083

and then change the status of the bug back to 'New'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Launchpad Janitor (janitor)]

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]