Re: Consistent file system hang with RELENG_6 of today ...

From: Marc G. Fournier (scrappy_at_hub.org)
Date: 07/29/05

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    Date: Fri, 29 Jul 2005 09:55:00 -0300 (ADT)
To: Robert Watson <rwatson@FreeBSD.org>

    Oh, before I forget ... how do you break to DDB from a serial console?
    I'll be running a Portmaster for this ...

    On Fri, 29 Jul 2005, Robert Watson wrote:

    >
    > On Thu, 28 Jul 2005, Marc G. Fournier wrote:
    >
    >> 'k, I'm starting to play with 6.x, for our new server ... my priority right
    >> now is to just have it run the existing 'jail' environments from my 4.x
    >> machine, while I work on getting all of our servers up to 6.x, and then
    >> will worry about the jail's themselves ...
    >>
    >> When I try and startup the 4.x jail on my 6.x machine, it "hangs" the file
    >> system that the jail directory hierarchy happens to be mounted on though
    >> ... twice in a row so far ...
    >>
    >> Now, I'm suspecting (and am going to try without it) that it might be
    >> because I'm mounting devfs within the 4.x jail, but even then, it shouldn't
    >> hang things up, only generate a whack of errors ...
    >>
    >> I have a good dump (CTL-ALT-ESC -> panic), but do not have a clue what to
    >> offer from within there that might be of any use ...
    >>
    >> If anyone is interested ... ?
    >
    > If you can get into DDB and have serial console output, the following would
    > be useful:
    >
    > The output of 'show pcpu'
    >
    > The output of 'show pcpu X' for each present cpu, starting with 0.
    >
    > The output of 'ps'
    >
    > The output of 'trace' for the currently running thread, and each non-idle
    > thread shown in the show pcpu output
    >
    > The output of 'show lockedvnods'
    >
    > It would also be useful if, relating to the startup of the jail, you can
    > identify the point in the jail boot where it wedges, and if you hit Ctrl-T,
    > what process is shown as running and what state it is in, and using DDB,
    > trace that process.
    >
    > If you could show the trace output for each process listed in "show
    > lockevnods".
    >
    > Likely, there is a leaked lock or a low buffer condition. However, once we
    > have the above output we should be able to say more. The above will
    > hopefully tell us whether it's a vnode deadlock, and ideally, the approximate
    > source.
    >
    > Robert N M Watson
    >
    > 

    ----
Marc G. Fournier           Hub.Org Networking Services (http://www.hub.org)
Email: scrappy@hub.org           Yahoo!: yscrappy              ICQ: 7615664
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