i386/137037: zfs rolback on root causes FreeBSD to freez in few seconds

[Aldis Berjoza]

>Number:         137037
>Category:       i386
>Synopsis:       zfs rolback on root causes FreeBSD to freez in few seconds
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    freebsd-i386
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Jul 23 17:00:05 UTC 2009
>Closed-Date:
>Last-Modified:
>Originator:     Aldis Berjoza
>Release:        FreeBSD 8.0-BETA2 i386
>Organization:
>Environment:


System: FreeBSD 8.0-BETA2 #0: Mon Jul 20 21:43:13 EEST 2009
    root at 192.168.128.100:/usr/obj/usr/src/sys/ANTIGENERIC



>Description:


I use geli encrypted disks. I Boot from usb flash...

When I run zfs rollback on root, after rollback is finished in few seconds system hangs and I have to manually reset PC.

When PC is up and running again, you can see, that rollback was sucessfull. All file system  modifications are gone, No disk corruption have ever been detected with zpool scrub

Here's relavent part of my pool setup:
FS			MOUNTPOINT
----------------------------
a			none
a/root		legacy (mounted on /)
a/src		/usr/src
a/tmp		/tmp

{I didn't seperate /usr and /var from root}

CPU: Intel Pentium 4 HTT enabled @ 3GHz
RAM: 2.5GB


>How-To-Repeat:


Install FreeBSD on ZFS.
make snapshot
modify root filesystem
rollback....


[Perhaps this problem only happens, if HDD's are geli encrypted, I have no way to test this)


>Fix:





>Release-Note:
>Audit-Trail:
>Unformatted: