* Fernando Lopez-Lezcano | 2015-08-06 10:50:22 [-0700]:

I've had a few hangs with nothing left behind to debug... but today I
find this:

----
Aug  5 10:46:18 localhost kernel: [ 2343.673560] WARNING: CPU: 3 PID:
43 at net/sched/sch_generic.c:303 dev_watchdog+0x26f/0x280()
Aug  5 10:46:18 localhost kernel: [ 2343.673561] NETDEV WATCHDOG:
eth1 (e1000e): transmit queue 0 timed out
----

Your network controller did not manage to send TX packets.

and then:

----
Aug  5 10:46:18 localhost kernel: [ 2343.673679] e1000e 0000:04:00.0
eth1: Reset adapter unexpectedly

this is the consequene of the former problem.

Aug  5 10:46:30 localhost kernel: [ 2355.706987] ata5.00: exception
Emask 0x40 SAct 0x0 SErr 0x80800 action 0x6 frozen
Aug  5 10:46:30 localhost kernel: [ 2355.706990] ata5: SError: {
HostInt 10B8B }
Aug  5 10:46:30 localhost kernel: [ 2355.707003] ata5.00: cmd
a0/00:00:00:08:00/00:00:00:00:00/a0 tag 0 pio 16392 in
Aug  5 10:46:30 localhost kernel: [ 2355.707003]          Get event
status notification 4a 01 00 00 10 00 00 00 08 00res
40/00:03:00:00:00/00:00:00:00:00/a0 Emask 0x44 (timeout)
Aug  5 10:46:30 localhost kernel: [ 2355.707005] ata5.00: status: { DRDY }
Aug  5 10:46:30 localhost kernel: [ 2355.707007] ata5: hard resetting link

And now ata5 (hard disk?) suddenly got another problem and the link gets
reset.

----
Aug  5 10:46:18 localhost kernel: WARNING: CPU: 3 PID: 43 at
net/sched/sch_generic.c:303 dev_watchdog+0x26f/0x280()
Aug  5 10:46:18 localhost kernel: NETDEV WATCHDOG: eth1 (e1000e):
transmit queue 0 timed out

ethernet is still not working.

Aug  5 11:58:36 localhost kernel: [ 6678.122596] Network
Receive[2409]: segfault at 28 ip 0000003c4c293ca9 sp 00007fb6f64dbb58
error 6 in libc-2.18.so[3c4c200000+1b4000]
Aug  5 11:58:36 localhost kernel: Network Receive[2409]: segfault at
28 ip 0000003c4c293ca9 sp 00007fb6f64dbb58 error 6 in
libc-2.18.so[3c4c200000+1b4000]

and now we have a segfault in libc. You box is kind of falling apart.

And eventually (later) get a ton of these:

----
Aug  5 11:59:36 localhost kernel: [ 6738.107181] INFO: rcu_preempt
detected stalls on CPUs/tasks: {} (detected by 3, t=60002 jiffies,
g=37092, c=37091, q=0)
Aug  5 11:59:36 localhost kernel: [ 6738.107183] All QSes seen, last
rcu_preempt kthread activity 1 (4301410925-4301410924),
jiffies_till_next_fqs=3, root ->qsmask 0x0

one CPU hangs and does not make any progress.

So something is left in a not good state...

Can you reproduce this and if so with and without -RT? There is nothing
in the what would indicate a -RT bug.

-- Fernando

Sebastian