Guest: DragonFly dfbsd 6.5-DEVELOPMENT #0: Thu Jul  2 06:02:54 UTC 2026
       root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC  x86_64
       (QEMU/KVM, 6 vCPU, 4GB; INVARIANTS stock kernel; hammer2 root fs)
Test fs: /dev/vn0 (vnconfig on /root/h2img, 512MB) newfs_hammer2, label DATA
Sysctls set for the runs: vfs.hammer2.limit_dirty_chains=16
                         vfs.hammer2.limit_dirty_inodes=4
Witness kernels (in-guest only, /usr/src reverted afterwards):
  #1/#2  witness v1/v2  (tsleep park, global scope)  - superseded
  #3     witness v3     (tsleep park, non-root-fs scope)
  #4/#5  witness v4     (parked counter + debug.df2832_stop sysctl)
         baseline run on #4-era build; fix-validation on #5:
         #5 = witness4 + fix.diff interlock + NULL guards + busy-spin park
Unpriv user: nobody (uid 65534). Binaries under /usr/local/df2832 (exec-allowed;
/tmp tmpfs denies exec for nobody -- cost us one full run to discover).