Hi. I'm still seeing this panic, although very occasionally, during bulkbuild. It's a DELL PowerEdge with Core 2 Duo and 2G bytes of RAM, running an SMP x86_64 kernel built from source as of c652b. The HAMMER filesystem is version 4 (originally version 2 but migrated to version 4 later), has never been filled up, and about 40% is in use. I have `daily_clean_hammer_enable="NO"' in /etc/periodic.conf and occasionally run `hammer cleanup /pfs/*', so no cleanup should be involved at the time of panic. I happened to be running two instances of hammer command at that time, one for iostats and another for bstats, but I'm not sure it's anything to do with the panic because I remember seeing the panic without those commands running.
The backtrace looks almost the same as that of i386 version, but I can upload the dump on leaf tomorrow if you think it's worth looking at it. Cheers.
