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Date:      Fri, 11 Jan 2002 00:33:01 -0800
From:      "Ted Mittelstaedt" <tedm@toybox.placo.com>
To:        <gnb@itga.com.au>
Cc:        <freebsd-bugs@FreeBSD.ORG>
Subject:   RE: kern/33637: Panic: vm_page_unwire: invalid wire count: 0 
Message-ID:  <000201c19a7a$94a7d840$1401a8c0@tedm.placo.com>
In-Reply-To: <200201102242.JAA15581@lightning.itga.com.au>

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>-----Original Message-----
>From: gnb@itga.com.au [mailto:gnb@itga.com.au]
>Sent: Thursday, January 10, 2002 2:42 PM
>To: Ted Mittelstaedt
>Cc: gnb@itga.com.au; freebsd-bugs@FreeBSD.ORG
>Subject: Re: kern/33637: Panic: vm_page_unwire: invalid wire count: 0
>
>
>>  The submitter of the PR
>> was operating under a false assumption - that he could run any program and
>> assume that it was impossible for it to crash the OS.
>
>But I don't think that is a false assumtion.  On the contrary, that
>is exactly
>what I would expect and hope to find from a "production quality" OS like
>FreeBSD.

If you give a program life-and-death authority over the system and
the program crashes the system then that is hardly a bug in the system,
now is it?

>
>IMO the submitter was being entirely reasonable in making that
>assumption - or
>at least, on finding a violation of that assumption, to report it
>and expect it
>to be treated as a bug.  (Even if the response is "we know it's a
>bug and it's
>hard to fix, here's a workaround using login.conf".)
>

But that WASN'T my response, re-read my response to the PR, I did
not tell him to fix his problem with login.conf.  I merely pointed him
to it because he stated:

"An application should not cause a kernel panic if it only uses
 the system calls documented in section 2 or the library functions
 documented in section 3 of the manual."

which is obviously incorrect, and if he read the manpage to login.conf
he would have realized this.

I'm not ruling out a kernel bug.  But the submitter had obviously ruled out
an application bug without any reason to do so, and in fact when the
preliminary evidence points to the application.  This is unreasonable.

>I guess we can agree to differ here, and I ain't nothing 'cept a user, but my
>gut feel is that the wider FreeBSD team tends to my way of thinking
>rather than
>yours!!!

I think your talking about a generalized philosophical stance
not a specific case of debugging.  I don't disagree with the philosophy
but I don't think it applies in this specific case.

The biggest problem with this PR is that the submitters attitude is wrong.

Yes, the submitter has a real problem.  Obviously he's frustrated.  Obviously,
in some piece of code somewhere, either in the application or in the OS,
there's
a bug that's causing this.

But these sorts of bug reports are worthless to the FreeBSD team if the
submitter
is going to jump to conclusions that it's an OS bug and not even _try_
pursuing
the possibility that it's an application bug.

The fact that the server was fine for
6 months till the application program was loaded on it couldn't scream out
"application bug" louder than if it was on the top of the mountain jumping up
and down.

Should a PR be put into the system saying something along the lines of:

"I ran a program that was limited to allocating 800MB of ram in login.conf
and my program attempted to allocate 10 GB of ram and my system has 500MB of
physical memory and 500MB of swap and the program crashed, but when I changed
the
program to run under a userID that is unlimited and ran it again, the
operating system crashed"


Ted Mittelstaedt                                       tedm@toybox.placo.com
Author of:                           The FreeBSD Corporate Networker's Guide
Book website:                          http://www.freebsd-corp-net-guide.com



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