kern/55934: kernel panics while restoring into vinum volume with 64MB RAM

[Thorsten Kuehnemann]

>Number:         55934
>Category:       kern
>Synopsis:       kernel panics while restoring into vinum volume with 64MB RAM
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Sun Aug 24 13:20:09 PDT 2003
>Closed-Date:
>Last-Modified:
>Originator:     Thorsten Kuehnemann
>Release:        FreeBSD 5.1-RELEASE-p2 i386
>Organization:
private
>Environment:
System: FreeBSD ef80.jnx.de 5.1-RELEASE-p2 FreeBSD 5.1-RELEASE-p2 #0: Wed Aug 20 13:41:44 CEST 2003 tk at ef80.jnx.de:/home/usr/obj/home/usr/src/sys/GENERIC-DEBUG i386
	GENERIC-DEBUG is GENERIC with activated "makeoptions DEBUG=-g"
	
	The machine has only 64 MB RAM.

>Description:
	While restoring a filesystem into a vinum volume /dev/vinum/root
	the kernel panics with the message:
	   panic: kmem_malloc(4096): kmem_map too small: 27398144 total allocated

	Restoring the same data into a manually calculated overlay
	partition /dev/da0s1a (as described in Chapter 13.9.2 of the Handbook)
	works without problems.
>How-To-Repeat:
	On a system with only 64 MB RAM create a big vinum volume for
	root and start to dump/restore all filesystems (with populated
	/usr/src and /usr/ports) into the new volume.
>Fix:
	1. Add the following line to the file /boot/lader.conf:
	   kern.vm.kmem.size="59000000"

	Question to the kernel expert: Is it a good idea to change
	the default calculation of vm_kmem_size in
	/sys/kern/kern_malloc.c for low memory systems
	(for example lower VM_KMEM_SIZE_SCALE)???

	or

	2. Inrease the physical RAM size to a minimum of 128MB.
>Release-Note:
>Audit-Trail:
>Unformatted: