[Bug 1572608] Re: Samba 2:4.3.8+dfsg-0ubuntu0.14.04.2 Reversion: CPU Soft Lock
Gavin Chappell
1572608 at bugs.launchpad.net
Thu May 12 17:50:06 UTC 2016
I'm seeing similar behaviour too - on a Ubuntu 14.04.4 box, completely
up to date. I just had it freeze, which marks the third or fourth time
I've either had to Magic-SysRq it, or pull the power, since the Badlock
date.
The box has "plenty" of RAM (it was recently upgraded from 8GB to 16GB
in fact, some time in March) but I don't believe this issue ever
happened with 8GB and Samba 4.1.6. It acts as a file server for a small
office of 12 people, which I think would count as lightly loaded in
terms of Samba installations?
All I have so far is a snippet from /var/log/kernel.log of the call
trace which I've attached. If there is more information that would be
useful next time this happens, let me know what you need and I'll get
it. Unfortunately there is (currently) no load monitoring on this box,
so I don't know whether we're getting a similar increase in iowait time
before the crash - although the box is logging soft lockup errors, from
a user perspective the box is working perfectly fine until it freezes
altogether and stops responding to pings or console activity.
** Attachment added: "Sample smb lockup error - there are many more of these before the box froze"
https://bugs.launchpad.net/ubuntu/+source/samba/+bug/1572608/+attachment/4661413/+files/octanesmb.txt
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https://bugs.launchpad.net/bugs/1572608
Title:
Samba 2:4.3.8+dfsg-0ubuntu0.14.04.2 Reversion: CPU Soft Lock
Status in samba package in Ubuntu:
Confirmed
Bug description:
Upon upgrading to Samba 4.3.8, I encounter crippling soft lockup
problems with smbd. The kernel will start throwing errors (see below)
about what appears to be the root smbd process, and the locked process
eventually cripples all smb connections to the server. Further, the
process is sufficiently locked that SIGKILL has no effect. While the
process is locked, the system shows steadily increasing iowait on the
CPU.
/var/log/error excerpt:
Apr 20 09:34:17 banner kernel: BUG: soft lockup - CPU#7 stuck for 22s! [smbd:9842]
Apr 20 09:34:45 banner kernel: BUG: soft lockup - CPU#7 stuck for 22s! [smbd:9842]
Apr 20 09:35:13 banner kernel: BUG: soft lockup - CPU#7 stuck for 22s! [smbd:9842]
Apr 20 09:35:41 banner kernel: BUG: soft lockup - CPU#7 stuck for 22s! [smbd:9842]
Apr 20 09:36:09 banner kernel: BUG: soft lockup - CPU#7 stuck for 22s! [smbd:9842]
Apr 20 09:36:37 banner kernel: BUG: soft lockup - CPU#7 stuck for 22s! [smbd:9842]
Apr 20 09:36:51 banner kernel: INFO: rcu_sched self-detected stall on CPU { 7}(t=240025 jiffies g=7144731 c=7144730 q=0)
smb.conf global options:
[global]
workgroup = [redacted]
server string = Samba Server Version %v
interfaces = lo eth0
hosts allow = [redacted]
socket options = SO_SNDBUF=16384 SO_RCVBUF=16384 TCP_NODELAY
syslog only = yes
security = ads
passdb backend = tdbsam
realm = [redacted]
winbind nss info = rfc2307
idmap config * :backend = tdb
idmap config * :range = 10000000-11000000
idmap config [redacted]:schema_mode = rfc2307
idmap config [redacted]:backend = ad
idmap config [redacted]:range = 1000-9999999
idmap config [redacted]:default = yes
winbind use default domain = true
winbind offline logon = false
winbind enum users = no
winbind enum groups = no
winbind nested groups = yes
winbind expand groups = 4
winbind separator = /
winbind refresh tickets = yes
kerberos method = secrets and keytab
template homedir = /home/%U
template shell = /bin/bash
vfs objects = acl_xattr
map acl inherit = yes
store dos attributes = yes
server signing = auto
winbind sealed pipes = false
require strong key = false
winbind sealed pipes:[redacted] = true
require strong key:[redacted] = true
preferred master = no
wins support = no
wins proxy = no
dns proxy = no
load printers = no
cups options = raw
Release Info:
Description: Ubuntu 14.04.4 LTS
Release: 14.04
I will also note that the Samba shares are living on Ceph RBD volumes
formatted as XFS. It seems unlikely, but it's conceivable that Samba
4.3.8 introduced some new conflict with the kernel RBD module.
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