[Bug 585208] [NEW] slapd becomes non-responsive after several weeks runtime

[Craig Ringer]

Public bug reported:

I use an Ubuntu 10.04 (lucid) server for, among other things, LDAP
authentication.

slapd:
  Installed: 2.4.21-0ubuntu5
  Candidate: 2.4.21-0ubuntu5
  Version table:
 *** 2.4.21-0ubuntu5 0
        500 http://ftp.iinet.net.au/pub/ubuntu/ lucid/main Packages
        500 http://au.archive.ubuntu.com/ubuntu/ lucid/main Packages
        100 /var/lib/dpkg/status

Distributor ID: Ubuntu
Description:    Ubuntu 10.04 LTS
Release:        10.04
Codename:       lucid

With Ubuntu 9.10 it was stable and well-behaved. Since upgrading to
10.04, however, I've been seeing issues where slapd stops responding to
ldap queries after several weeks of uptime. slapd has to be killed and
re-launched to get it working again.

I haven't found any way to reproduce this except waiting. The delay
before it happens is variable, from a few days to a few weeks.

All other daemons on the server are stable and well behaved. The issue
appears to be restricted to slapd.

After the second time this happened, I tried to dump a core from slapd
so I could debug it after I'd restarted it to restore services. However,
gcore reported the following error:

/root/slapd.core.gMMj3g:1: Error in sourced command file:
Cannot access memory at address 0x1fe8513
gcore: failed to create slapd.core.25525

and when I attached gdb directly to attempt to just get a backtrace, it
failed in a similar manner:

Attaching to process 25525
Reading symbols from /usr/sbin/slapd...Reading symbols from /usr/lib/debug/usr/sbin/slapd...done.
done.
Cannot access memory at address 0x1fe8513


... making it rather hard to collect debug information. A backtrace requested after that error is essentially useless, as it contains no symbols, only '???' and addresses.

This time when it happened I collected some information from slapd's
/proc entry before re-starting the process. It's all I could come up
with, and it didn't tell me much. I'll attach the files from /proc here.

Ideas? Can this be caused by a slapd bug? Or should I be looking for a
kernel bug?

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

-- 
slapd becomes non-responsive after several weeks runtime
https://bugs.launchpad.net/bugs/585208
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