kern/43800: PUFFS kernel crash

[manua%netbsd.org@localhost]

>Number:         43800
>Category:       kern
>Synopsis:       PUFFS kernel crash
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Aug 26 04:55:00 +0000 2010
>Originator:     Emmanuel Dreyfus
>Release:        NetBSD-5.0.2/i386
>Organization:
NetBSD
>Environment:
NetBSD bacasable.net.espci.fr 5.0.2 NetBSD 5.0.2 (XEN3_DOMU_PUFFS) #1: Thu Aug 
19 19:08:58 CEST 2010  
root@lego:/pkg_comp/NetBSD-5.0.2/src/sys/arch/i386/compile/obj/XEN3_DOMU_PUFFS 
i386
>Description:
high write activity on PUFFS using perfuse and fuse cause a kernel panic:
panic: genfs_getpages: past eof: 8192 vs. 0

>How-To-Repeat:
On NetBSD-5.0.2 or NetBSD-current, 
- install pkgsrc/filesystems/fuse
Binary package available from 
ftp://ftp.espci.fr/pub/pkgsrc/packages/NetBSD-5.0.2/i386/All

- download and unpack fuse-2.8.4 source:
http://sourceforge.net/projects/fuse/files/fuse-2.X/

- build fusexmp:
cd fuse-2.8.4/example
cc -D_FILE_OFFSET_BITS=64 -I/usr/pkg/include -c fusexmp.c
cc -L /usr/pkg/lib -lfuse -o fusexmp fusexmp.o 

- start perfused in debug mode ona terminal:
perfused -d fuse -f 

- start fusexmp
fusexmp -d -f /mnt

- run this enough time to get a panic (between 10 and 30 concurrent processes 
are required)
 ( cat < /dev/zero > /mnt/test ) &
>Fix:
Hi, Pooka!