enterprise-support team mailing list archive

[Ed Huyer <arcanum3000@xxxxxxxxx>]

Public bug reported:

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.

** Affects: samba (Ubuntu)
     Importance: Undecided
         Status: New

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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

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