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Thread: BUG: recent printk recursion!

  1. #1
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    Default BUG: recent printk recursion!

    Anybody else seeing this message in syslog? A search of the forums reveals nothing.

    Background:
    • OpenVZ Link-5 server (2.6.18-128.1.1.el5.028stab062.3)
    • Gentoo (up to date)
    • syslog-ng
    • iptables firewall in place (some rules are logging)


    I'm seeing the messages in the subject at syslog facility "kern". It appears to be related to iptables log messages. Not sure when this started, but it seems recent (mybe when my server was upgraded to new hardware [for which I am extremely grateful!]?).

    OpenVZ forums show that this is a known bug (OpenVZ Forum: Support => [solved] printk recursion) with a patch, but the kernel version running seems not to include that patch. Has anyone filed a support request with our host?

    Thanks,

    David Klann

  2. #2
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    Our system administrators are aware of this issue and we are looking into a patch to address it in the future (we plan to administer the patch as part of our network-wide OpenVZ kernel upgrades).

    In the meantime, this bug should not pose any threats to system stability or general VPS operations - while it will be an annoyance for log analysis, the alternative would be to move back to a hardware node running an older kernel which may not be compatible with the latest distribution releases.

  3. #3
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    Default Thanks for the Update

    I kinda figured you were on it, but didn't want to bother you with a support request.

    Thanks for replying!

    ~David

  4. #4
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    David,

    You may have already figured this out, but if the entries are still showing up, perhaps modifying syslog-ng.conf to something along the lines of...
    Code:
    filter f_fwdropped { match ( ".*IN=.*OUT=.*MAC=.*" ) and not match ( ".*recent printk recursion.*" ); };
    would stop the entries from being logged? An ITIL shop would probably consider this a work-around at least until the permanent resolution is implemented.

    DanL,

    Does VPSlink follow or adhere to any "best practice" frameworks? Does VPSlink have a change advisory board, KeDB, CMDB, risk assessment (management) team, etc, etc? Just curious

    -Guy

  5. #5
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    Quote Originally Posted by GuyPatterson View Post
    Does VPSlink follow or adhere to any "best practice" frameworks? Does VPSlink have a change advisory board, KeDB, CMDB, risk assessment (management) team, etc, etc?
    We rely heavily on the expertise of our systems administrators to "get it right" - our present safeguards against poorly-informed configurations consist primarily of following the stable releases of the operating systems and virtualization platforms which we deploy.

    Given the choice between a bleeding-edge version and a version which has been thoroughly vetted, we will always go with the option in which bugs are (a) known and (b) of low impact to core operations... which may explain why our software releases are few and far between.

    We've implemented CMDB for all hardware nodes (not so for virtual private servers - we've experimented with it in the past to prevent resource abuse issues and we've found that it's better to deal with resource abuse via monitoring and human intervention) and we have an internal wiki which functions as our KeDB with links to relevant project bug trackers and any errata we've discovered as it applies to our systems.

  6. #6
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    Quote Originally Posted by DanL@VPSLink View Post
    Our system administrators are aware of this issue and we are looking into a patch to address it in the future (we plan to administer the patch as part of our network-wide OpenVZ kernel upgrades).
    Wow, so now that I've experienced this issue for myself, it's pretty obnoxious. Any idea when the patch/fix will be applied?

    http://1284.bugzilla.openvz.org/attachment.cgi?id=1017

    Not having logs poses a threat to security :/ I'm a huge fan of logs

  7. #7
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    Quote Originally Posted by GuyPatterson View Post
    Wow, so now that I've experienced this issue for myself, it's pretty obnoxious. Any idea when the patch/fix will be applied?
    I should have an answer for you in the near future - will post back after speaking with our systems administration team.

    We've had to postpone the next wave of Xen kernel upgrades as several of our systems administrators are out sick at this time, however, following next Thursday's Xen upgrades I believe that upgrades for all OpenVZ nodes will be a top priority.

  8. #8
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    Update: Our systems administration team reports that OpenVZ kernel upgrades are to be completed for all OpenVZ hardware nodes within 3-4 weeks (this should serve as a conservative estimate; notifications will be sent in advance of kernel upgrades).

    If this bug poses a serious problem to your use of our service we do have the option to migrate accounts to nodes which have already been updated to our latest OpenVZ kernel - please contact our support team to inquire about a migration if this bug poses an issue to the stability or critical functionality of your VPS.

  9. #9
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    Just wanted to say this issue has been resolved on my Link6 at the Seattle DC. Thanks a lot to DanL and the VPSlink sys-admins for their prompt response. IPtables logs are back in action

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