Hi,
in the dmesg log (actually "journalctl -f") of one of my machines I had this:
...
03:25:01 CRON[16607]: pam_unix(cron:session): session closed for user root
INFO: rcu_preempt detected stalls on CPUs/tasks:
1-...: (1 GPs behind) idle=763/140000000000000/0 softirq=6109762/6109762
fqs=301
2-...: (1 GPs behind) idle=2f3/140000000000000/0 softirq=5129036/5129037
fqs=301
(detected by 0, t=303 jiffies, g=2533688, c=2533687, q=4860)
INFO: rcu_preempt detected stalls on CPUs/tasks:
1-...: (1 GPs behind) idle=763/140000000000000/0 softirq=6109762/6109762
fqs=1204
2-...: (1 GPs behind) idle=2f3/140000000000000/0 softirq=5129036/5129037
fqs=1205
(detected by 0, t=1208 jiffies, g=2533688, c=2533687, q=19822)
INFO: rcu_preempt detected stalls on CPUs/tasks:
1-...: (1 GPs behind) idle=763/140000000000000/0 softirq=6109762/6109762
fqs=2109
2-...: (1 GPs behind) idle=2f3/140000000000000/0 softirq=5129036/5129037
fqs=2109
(detected by 0, t=2113 jiffies, g=2533688, c=2533687, q=34248)
INFO: rcu_preempt detected stalls on CPUs/tasks:
1-...: (1 GPs behind) idle=763/140000000000000/0 softirq=6109762/6109762
fqs=3011
2-...: (1 GPs behind) idle=2f3/140000000000000/0 softirq=5129036/5129037
fqs=3011
(detected by 0, t=3018 jiffies, g=2533688, c=2533687, q=48662)
INFO: rcu_preempt detected stalls on CPUs/tasks:
1-...: (1 GPs behind) idle=763/140000000000000/0 softirq=6109762/6109762
fqs=3912
2-...: (1 GPs behind) idle=2f3/140000000000000/0 softirq=5129036/5129037
fqs=3912
(detected by 0, t=3923 jiffies, g=2533688, c=2533687, q=63080)
INFO: rcu_preempt detected stalls on CPUs/tasks:
1-...: (1 GPs behind) idle=763/140000000000000/0 softirq=6109762/6109762
fqs=4815
2-...: (1 GPs behind) idle=2f3/140000000000000/0 softirq=5129036/5129037
fqs=4815
(detected by 0, t=4828 jiffies, g=2533688, c=2533687, q=68037)
...
and so on, and so forth ...
...
INFO: rcu_preempt detected stalls on CPUs/tasks:
1-...: (1 GPs behind) idle=763/140000000000000/0 softirq=6109762/6109762
fqs=137745
2-...: (1 GPs behind) idle=2f3/140000000000000/0 softirq=5129036/5129037
fqs=137746
(detected by 0, t=137863 jiffies, g=2533688, c=2533687, q=68849)
INFO: rcu_preempt detected stalls on CPUs/tasks:
1-...: (1 GPs behind) idle=763/140000000000000/0 softirq=6109762/6109762
fqs=138651
2-...: (1 GPs behind) idle=2f3/140000000000000/0 softirq=5129036/5129037
fqs=138652
