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Subject: kern/3278: MFS chews up all swap space
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>Number:         3278
>Category:       kern
>Synopsis:       mounting MFS uses up swap space
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Apr 13 21:40:01 PDT 1997
>Last-Modified:
>Originator:     Jonathan Lemon
>Organization:
>Release:        FreeBSD 3.0-CURRENT i386
>Environment:

	FreeBSD 3.0-CURRENT #0: Sun Apr 13 21:55:38 CDT 1997
	
	Machine with 32M memory, 71M swap

>Description:

	Mounting MFS filesystem causes roughly 2x physical memory to
	be allocated in swap partition, even though almost nothing 
	is running.  System then slowly runs out of swap, resulting in
	signal 6's to most processes, and cumulates with a panic in
	update that ususally looks like:

		lockstatus(34)
		ufs_islocked()
		vfs_msync()
		sync()
		vfs_update()

	
>How-To-Repeat:

	# grep swap /etc/fstab    
	/dev/sd3s2b             none            swap    sw              0 0

	# swapinfo
	Device      1K-blocks     Used    Avail Capacity  Type
	/dev/sd3s2b     73728        0    73664     0%    Interleaved
 
	# mount -t mfs /dev/sd3s2b /tmp    

	# swapinfo
	Device      1K-blocks     Used    Avail Capacity  Type
	/dev/sd3s2b     73728    68184     5480    93%    Interleaved

	# umount /tmp

	# swapinfo    
	Device      1K-blocks     Used    Avail Capacity  Type
	/dev/sd3s2b     73728    10488    63176    14%    Interleaved

>Fix:
	
	Don't use MFS, until fixed.

>Audit-Trail:
>Unformatted: