=== BASELINE (unpatched #0 kernel) ===
kern.version: DragonFly 6.5-DEVELOPMENT #0: Thu Jul  2 06:02:54 UTC 2026

PoC: /root/poc/DF-0019/df0019 24  (switches to bsd4 scheduler, sets queue_checks=0, forks 24 CPU-bound kids)

[*] switching pid 863 to bsd4 scheduler...
[+] now running under bsd4 scheduler.
[*] setting kern.usched_bsd4.queue_checks=0...
kern.usched_bsd4.queue_checks: 5 -> 0
[*] forking 24 CPU-bound bsd4 kids...
SSH_RC=124  (timeout — guest panicked)

=== PANIC SIGNATURE (from dfbsd-qemu/boot.log serial console) ===
panic with 1 spinlocks held
panic: chooseproc: at least the first lp was good
cpuid = 2
Trace beginning at frame 0xfffff80118c977f8
bsd4_release_curproc() at bsd4_release_curproc+0x89a 0xffffffff8066874a 
bsd4_release_curproc() at bsd4_release_curproc+0x89a 0xffffffff8066874a 
bsd4_acquire_curproc() at bsd4_acquire_curproc+0x17d 0xffffffff80669d7d 
syscall2() at syscall2+0x213 0xffffffff80bd6b03 
Debugger("panic")
Stopped at      Debugger+0x7c:  movb    $0,0xbdaf09(%rip)
db> 

Result: KERNEL PANIC. Guest is down (in DDB). Bug reproduced.