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Date:      Sun, 15 Feb 1998 19:01:44 -0800
From:      Mike Smith <mike@smith.net.au>
To:        Terry Lambert <tlambert@primenet.com>
Cc:        sthaug@nethelp.no, roberto@keltia.freenix.fr, hackers@FreeBSD.ORG
Subject:   Re: VM messed: vm_page_free panic problem 
Message-ID:  <199802160301.TAA04333@dingo.cdrom.com>
In-Reply-To: Your message of "Mon, 16 Feb 1998 02:48:33 GMT." <199802160248.TAA20273@usr05.primenet.com> 

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> > boot.flp from 3.0-980206-SNAP (from releng22.freebsd.org) panics at the
> > end of the boot process, with:
> > 
> > changing root device to fd0c
> > rootfs is 1440 KByte compiled in MFS
> > vm_page_free: pindex(12), busy(0), PG_BUSY(0), hold(0)
> > panic: vm_page_free: freeing free page
> > 
> > boot.flp from 3.0-980204-SNAP works okay.
> > 
> > It's very much reproducible - the panic occurs every time :-). The numbers
> > in the parentheses are the same every time. I've tried it on a PPro-200
> > with 64 mByte memory, and an AMD 5x86-133 with 24 MByte memory.
> 
> OK.  Disable the PSE.  The problem seems (to me) to be that there is a
> requirement for more than 4M for the kernel, but with PSE enables, there
> is only a single 4M page.  The MFS pushes the page boundry out, and
> then you fail when you try to page in from the unmapped region of the
> MFS.

Uh, can you wait until I have at least had a chance to explain it to 
you, Terry?

You can't "disable PSE" without a laser.  You can try waiting for the 
next SNAP bootimage, where I have tried disabling support for the 4MB 
page, pending a better fix.

> I would be surprised if these disks would boot on a 5M system without
> PSE capability.  I think we are talking 6M now.

The entire BOOTMFS image is a bit under 3MB.  5MB is probably still 
workable, but the installation will be slower than if you have 8MB+ 
(buffer cache, less MFS paging, etc.)

> The easiest test would be to build a distribution after defining DISABLE_PSE,
> and see if those boot.

Try the next SNAP from current.freebsd.org.  I expect we'll hear about 
it one way or the other. 8)

-- 
\\  Sometimes you're ahead,       \\  Mike Smith
\\  sometimes you're behind.      \\  mike@smith.net.au
\\  The race is long, and in the  \\  msmith@freebsd.org
\\  end it's only with yourself.  \\  msmith@cdrom.com



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