/proc/$PID/stat overflowed task utime

If you happen to see a bogus task run time (overflowed user time)/cpu usage/etc. in top
or ps output with recent kernels

 $ 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


cat /proc/10/stat
10 (rcu_preempt) S 2 0 0 0 -1 2129984 0 0 0 0 1844674407370 477 0 0 20 0 1 0 10 0 0 18446744073709551615 0 0 0 0 0 0 0 2147483647 0


then you probably would be interested in cherry picking commit 5a8e01f8fa51f5cbce8f37acc050eb2319d12956
by Stanislaw Gruszka (or just wait for the next stable release).