I've been seeing a panic on my FreeBSD/ZFS server (running 9-STABLE built on 6/28), where the relevant line appears to be: avl_find() succeeded inside avl_add() I found a patch pjd committed to trunk (r230454), which apparently was supposed to be MFC'd a week later, but it doesn't appear to be in FreeBSD 9-STABLE yet. I rebuilt my kernel with this patch applied and the server has been fairly stable for over 24h now, and the things I was doing that caused it to kernel panic previously are now working fine. The filesystems were created with 'zfs recv' from an older OpenSolaris installation. Any chance this might make it into FreeBSD for 9.1? -clee