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Date:      Mon, 23 Apr 2007 17:35:47 +0200
From:      Kai <kai@xs4all.nl>
To:        stable@freebsd.org
Subject:   Re: Fatal trap 12: page fault while in kernel mode
Message-ID:  <20070423153547.GD20155@xs4all.nl>
In-Reply-To: <20070419123329.GA10189@xs4all.nl>
References:  <20070411105332.GC7847@xs4all.nl> <20070419123329.GA10189@xs4all.nl>

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On Thu, Apr 19, 2007 at 02:33:29PM +0200, Kai wrote:
> On Wed, Apr 11, 2007 at 12:53:32PM +0200, Kai wrote:
> > 
> > Hello all,
> > 
> > We're running into regular panics on our webserver after upgrading
> > from 4.x to 6.2-stable:
> 

Hi all,

To continue this story, a colleague wrote a small program in C that launches
40 threads to randomly append and write to 10 files on an NFS mounted
filesystem. 

If I keep removing the files on one of the other machines in a while loop,
the first system panics:

Fatal trap 12: page fault while in kernel mode
cpuid = 1; apic id = 01
fault virtual address   = 0x34
fault code              = supervisor read, page not present
instruction pointer     = 0x20:0xc06bdefa
stack pointer           = 0x28:0xeb9f69b8
frame pointer           = 0x28:0xeb9f69c4
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         = 73626 (nfscrash)
trap number             = 12
panic: page fault
cpuid = 1
Uptime: 3h2m14s

Sounds like a nice denial of service problem. I can hand the program to
developers on request.

Regards,
Kai Storbeck
-- 
This was an above the .signature production



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