=== DF-3076 baseline run (stock INVARIANTS kernel #0) ===
$ guest# sh run76.sh A  (forge 512K data_len into last DATA record, mount nohistory)
version=7 buf_beg=557056 btree_root=8000000021000000 newlen=524288
FOUND DATA rec: key=0000000000110000 data_off=a000000022000000 data_len=65536 (zone 10) node=8000000021000000 elm=4
PATCH best-key record: key=0000000000110000 data_len 65536 -> 524288 (0x80000)
DONE patched=1
MOUNT_OK variant=A len=0x80000
total 2176
-rw-r--r-- 1 root wheel 1049600 Sep 6 00:39 target.bin

$ vm.sh run_user (uid=1001 maxx): rm -f /mnt/target.bin  -> RM_RC=0
(destruction is asynchronous: flusher slave -> hammer_sync_inode)

=== serial console (decisive) ===
panic: assertion "bytes <= HAMMER_XBUFSIZE" failed in hammer_blockmap_free at /usr/src/sys/vfs/hammer/hammer_blockmap.c:786
cpuid = 3
Trace beginning at frame 0xfffff80118a43720
hammer_blockmap_free() at hammer_blockmap_free+0x39a 0xffffffff8092751a 
hammer_blockmap_free() at hammer_blockmap_free+0x39a 0xffffffff8092751a 
hammer_delete_at_cursor() at hammer_delete_at_cursor+0x6b9 0xffffffff80944339 
hammer_ip_delete_range() at hammer_ip_delete_range+0x18f 0xffffffff809446ef 
hammer_sync_inode() at hammer_sync_inode+0x3c7 0xffffffff80937ad7 
hammer_flusher_slave_thread() at hammer_flusher_slave_thread+0x1c2 0xffffffff80933492 
Debugger("panic")

CPU3 stopping CPUs: 0x00000037
 stopped
Stopped at      Debugger+0x7c:  movb    $0,0xbdaf09(%rip)