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Received: (from jhay@localhost) by zibbi.mikom.csir.co.za (8.6.12/8.6.9) id WAA17044 for freebsd-current@FreeBSD.ORG; Fri, 1 Mar 1996 22:17:58 +0200
From: John Hay <jhay@mikom.csir.co.za>
Message-Id: <199603012017.WAA17044@zibbi.mikom.csir.co.za>
Subject: Re: rename panics kernel
To: freebsd-current@FreeBSD.ORG (FreeBSD-current)
Date: Fri, 1 Mar 1996 22:17:58 +0200 (SAT)
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> Resently I got a "panic : vrele : negative reference count".
> The vrele() was called from rename().
> 
> I tried a simple script to exercise rename (attached below) and a
> current system seems to panic (trapped in ufs_rename).  There's a race
> condition lurking, it seems. I havent tried other than the sticky /tmp
> directory as the source and target files parent directory. Also the
> test was run under root's account, if it matters.
> 
> Rename exercise:
> ------
> #!/bin/sh
> a=/tmp/foo.now
> b=/tmp/foo.prev
> while true
> do
>         for n in 1 2 3 4 5 6 7 8 9 0
>         do
>                 (mv $a $b ; touch $a) &
>         done
>         wait
> done
> ------
> 

Well I tried this on a -stable machine and one with -current. Both did
panic. :-( The -current kernel is a week old. Here is its panic message:

Fatal trap 12: page fault while in kernel mode
fault virtual address   = 0x68
fault code              = supervisor read, page not present
instruction pointer     = 0x8:0xf015ffb9
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, def32 1, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 341 (mv)
interrupt mask          = 
panic: page fault

f015feb4 t _ufs_chown
f015ff78 T _ufs_ioctl
f015ff84 T _ufs_select
f015ff90 T _ufs_mmap
f015ff9c T _ufs_seek
f015ffa4 T _ufs_remove
f0160028 T _ufs_link
f01602b8 T _ufs_rename
f0160cf8 T _ufs_mkdir
f0160f70 T _ufs_rmdir
f01610cc T _ufs_symlink


John
---
John Hay -- John.Hay@csir.co.za