# DF-2881 PoC evidence pack

## What
Duplicate swap devices via distinct vnodes over the same storage: whole-disk /dev/vn0 and compat-slice /dev/vn0s0 both swapped on simultaneously.

## Build
```
(none: stock swapon/vnconfig)
```

## Run
```
truncate -s 2147483648 /swaptest.img; vnconfig -c vn0 /swaptest.img; swapon /dev/vn0; swapon /dev/vn0s0; swapinfo; swapoff both
```

## Expected
swapon /dev/vn0 rc=0; swapon /dev/vn0s0 rc=0 (no EBUSY); swapinfo lists BOTH devices over the same backing file

Guest: DragonFly dfbsd 6.5-DEVELOPMENT DragonFly 6.5-DEVELOPMENT #0: Thu Jul  2 06:02:04 UTC 2026     root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC  x86_64
All logs are full untrimmed captures unless noted. fix.diff is the
git-apply-able verified fix (authored after verification; never applied
to the audit tree).