Arch Linux

jackwild

Member

Registered: 2014-01-15

Posts: 30

[SOLVED?]Soft(?) lockup, how to debug?

So I've been having this issue since 3.14. Seemingly randomly I get a total freeze, no caps lock or numlock lights but I can use the magic sysreq combinations to reboot. I can't switch VTs. The logs have nothing for me, probably not been flushed to disk (flushing is at 5min default). I've been trying to narrow down the cause but I am a little at a loss.

I've just downgraded to 3.13.7-1 and I don't know if it's going to help yet, I'm not even sure if it's a kernel issue.

I've run memtest86+ successfully, disabled precache,preload and zswap as these are things I had enabled recently but the problem persists.

I'm going to change the log flushing to a lower value (5 seconds) and I haven't tried to SSH  from another box yet, but I will next time it happens.

What else can I do to find the cause of this?

I haven't included any extra information as I don't have anything which seems relevant. Ask and ye shall receive though.

Edit: I think it's solved. See https://bbs.archlinux.org/viewtopic.php?pid=1431047

Last edited by jackwild (2014-06-28 18:33:17)

ewaller

Administrator

From: Pasadena, CA

Registered: 2009-07-13

Posts: 19,804

Re: [SOLVED?]Soft(?) lockup, how to debug?

Other things to try.  Can you ping the box over the net when it is hung?  Can you ssh into the box when it is hung?

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jackwild

Member

Registered: 2014-01-15

Posts: 30

Re: [SOLVED?]Soft(?) lockup, how to debug?

I can't find a way to reliably reproduce this so i'm left with waiting for it to happen. I can leave it stress testing the CPU for over two hours without issue so I think that overhaeting is basically ruled out. It just did with 3.15.1-1-ARCH.

I can ping over the network but ssh gets stuck before authentication, it just hangs. Output of ssh -vvv:

OpenSSH_6.6.1, OpenSSL 1.0.1h 5 Jun 2014
debug1: Reading configuration data /etc/ssh/ssh_config
debug2: ssh_connect: needpriv 0
debug1: Connecting to 192.168.1.2 [192.168.1.2] port 22.
debug1: Connection established.
debug1: identity file /home/arch/.ssh/id_rsa type -1
debug1: identity file /home/arch/.ssh/id_rsa-cert type -1
debug1: identity file /home/arch/.ssh/id_dsa type -1
debug1: identity file /home/arch/.ssh/id_dsa-cert type -1
debug1: identity file /home/arch/.ssh/id_ecdsa type -1
debug1: identity file /home/arch/.ssh/id_ecdsa-cert type -1
debug1: identity file /home/arch/.ssh/id_ed25519 type -1
debug1: identity file /home/arch/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_6.6.1

Again, the last log entry is about 10 minutes before it happened so it isn't a flushing issue. I'm really stuck here. I'll have to try different kernel versions in hope. Any ideas welcomed.