Problem, on `gnu', early on 2009-01-11.
Took a disk partition image from `nlab', to mount on `gnu' with:
# mount -t reiserfs -o loop,notail,rw file.img /mnt/dsk
(This was because the system running on nlab was a RHEL-based
one, Scientific Linux, without reiserfs support; the content
of this reiserfs partition, a P4 Gentoo system, was wanted.)

kernel message for mounting the image:
Jan 11 01:59:42 gnu kernel: ReiserFS: loop0: found reiserfs format "3.6" with standard journal
Jan 11 01:59:42 gnu kernel: ReiserFS: loop0: using ordered data mode
Jan 11 01:59:42 gnu kernel: ReiserFS: loop0: journal params: device loop0, size 8192, journal first block 18, max trans len 1024, max batch 900, max commit age 30, max trans age 30
Jan 11 01:59:42 gnu kernel: ReiserFS: loop0: checking transaction log (loop0)
Jan 11 01:59:43 gnu kernel: ReiserFS: loop0: Using r5 hash to sort names
Jan 11 02:00:08 gnu kernel: ReiserFS: loop0: found reiserfs format "3.6" with standard journal
Jan 11 02:00:08 gnu kernel: ReiserFS: loop0: using ordered data mode
Jan 11 02:00:08 gnu kernel: ReiserFS: loop0: journal params: device loop0, size 8192, journal first block 18, max trans len 1024, max batch 900, max commit age 30, max trans age 30
Jan 11 02:00:08 gnu kernel: ReiserFS: loop0: checking transaction log (loop0)
Jan 11 02:00:08 gnu kernel: ReiserFS: loop0: Using r5 hash to sort names

Within the mounted image, several changes were made, but when 
a recursive deletion of a quite large directory was made the 
machine froze; most inconvenient...

Next day, after reboot (thanks to Dmitry), the following messages were all
that came between the mounting and the reboot: 
Jan 11 02:00:56 gnu kernel: ReiserFS: loop0: warning: clm-2100: nesting info a different FS
Jan 11 02:01:28 gnu last message repeated 12 times
Jan 11 02:02:30 gnu last message repeated 3 times
Jan 11 02:04:11 gnu last message repeated 3 times
Jan 11 02:07:08 gnu last message repeated 17 times
Jan 11 02:08:17 gnu last message repeated 9 times

This seems very similar to 
http://lkml.indiana.edu/hypermail/linux/kernel/0507.3/0791.html:
	"I'm having a crash with reiserfs 3.6 + user quota enabled, 
	on 2.6.11.10 kernel (no smp), apparently when deleting files 
	(or maybe during a truncate operation).  The problem seems 
	to happen under high load. 
	When the error occurs, all the processes accessing the reiserfs 
	partition seems to hang. This problem happened several times 
	on different servers (having the same hardware configuration) 
	during last weeks."
	ReiserFS: sda3: warning: vs-15011: reiserfs_release_objectid: tried to free free object id (96557091)
	ReiserFS: sda3: warning: PAP-5660: reiserfs_do_truncate: wrong result -1 of search for [847141 185744 0xfffffffffffffff DIRECT]
	ReiserFS: sda3: warning: clm-2100: nesting info a different FS

although my kernel was 2.6.25-gentoo-r7 and it is suggested on other sites
that the 2.6.11 vintage had problems while later ones didn't.

I guess from this that gnu (with quotas enabled) suffered a similar
problem.  I'll waste no more time on that, but do things on a less 
important computer.  

Lessons:
	- (again, ...): don't fool about on a remote multi-user thing!!
	- using `exotic' filesystems has its problems: RedHat isn't totally stupid in its choice