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  • krb5-18.2: MDB_BAD_RSLOT: Invalid reuse of reader locktable slot

    From rachit chokshi@21:1/5 to All on Thu Jun 18 01:53:36 2020
    Hello,
    I was trying out the latest release hoping to reap the benefits of LMDB for
    our systems. However each time I start krb5kdc and kadmin processes
    separately (one after another/at a different point in time) I see below in krb5kdc logs.

    *LMDB read failure (path: /var/kerberos/krb5kdc/principal.mdb):
    MDB_BAD_RSLOT: Invalid reuse of reader locktable slot*

    This problem goes away when i restart both services at the same time by
    doing "*systemctl restart kadmin krb5kdc*". However if any of them is individually restarted later, the above error starts showing up again.

    i can post my conf files but this is a vanilla setup with only the " *[dbmodules]"* section added to *kdc.conf*, rest all is default. The distro
    I am using is fedora rawhide.

    If anybody has seen this, pointers in the correct direction are greatly appreciated. TIA :)

    Regards,
    Rachit

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  • From Greg Hudson@21:1/5 to rachit chokshi on Fri Jun 19 18:27:19 2020
    To: kerberos@mit.edu

    On 6/18/20 4:53 AM, rachit chokshi wrote:
    *LMDB read failure (path: /var/kerberos/krb5kdc/principal.mdb): MDB_BAD_RSLOT: Invalid reuse of reader locktable slot*

    After some off-list debugging, I determined that the LMDB reader table
    entries for krb5kdc and kadmind appear as stale to other processes and
    can be reclaimed, because both daemons open the DB before daemonizing.

    I have filed a ticket and a pull request:

    https://krbdev.mit.edu/rt/Ticket/Display.html?id=8918 https://github.com/krb5/krb5/pull/1088

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