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DragonFly bugs List (threaded) for 2010-12
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Re: locking against myself in getcacheblk()?

From: Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>
Date: Sun, 26 Dec 2010 11:09:17 -0800 (PST)

:I managed to trigger this panic while trying to find out how to
:reliably reproduce another panic (lockmgr: non-zero exclusive count).
:Just issue the following command on a machine running recent -DEVELOPMENT
:(either on i386 or x86_64):
:$ grep -r --mmap SomeString /usr/pkgsrc
:If this won't trigger the panic but you need kern/vmcore, please let me
:know and I can upload mine to my leaf account.
:Best Regards,
:YONETANI Tomokazu.

    How much ram do you have in that machine (so I can reproduce the test).
    I have a feeling that cache cycling of VM pages might tend to trigger
    the (second) panic more often.

    non-zero exclusive counts usually mean an extra lock release or a
    missing lock acquisition for a lockmgr lock.  It can be a little
    trickly if it is a vnode lock since a completely unrelated bit of
    code might be causing the situation and then later on a perfectly
    fine piece of code triggers it.

					Matthew Dillon 

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