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Date: Sat, 16 Oct 2004 21:36:58 -0700 (PDT)
From: Don Lewis <truckman@FreeBSD.org>
To: pjd@FreeBSD.org
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Subject: Re: Stable panic on shutdown: swapoff: failed to locate N swap
	blocks
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On 16 Oct, Pawel Jakub Dawidek wrote:
> On Sat, Oct 16, 2004 at 08:54:47AM +0400, Andrey Chernov wrote:
> +> On Sat, Oct 16, 2004 at 12:47:31AM -0400, David Schultz wrote:
> +> > Pawel has a patch that moves the swapoff() later in the shutdown
> +> > sequence, after all user processes have been killed.  It should
> +> > make swapoff() basically a no-op / sanity check, since nothing
> +> > should actually be paged out at that point.
> +> 
> +> Forward it to me, please, I'll test it.
> 
> 	http://people.freebsd.org/~pjd/patches/swapoff_all.patch
> 

This should probably be combined with vfs_umountall() to handle the
mutual interdependencies between regular file systems, file systems
stored on swap-backed md devices, and vnode-backed md devices used for
swap.  I have no idea how difficult this might be to implement.

Hopefully nobody swaps to a vnode-backed md device that resides in a
file system that is stored on a swap-backed md device ...