panic: vm_page_unhold: hold count < 0!!! cpuid = 1 time = 66 KDB: stack backtrace: db_trace_self_wrapper() at db_trace_self_wrapper+0x47/frame 0xfffffe0020f2b6d0 vpanic() at vpanic+0x1e0/frame 0xfffffe0020f2b730 panic() at panic+0x43/frame 0xfffffe0020f2b790 vm_page_unhold_pages() at vm_page_unhold_pages+0x1e3/frame 0xfffffe0020f2b7e0 pipe_write() at pipe_write+0x16d8/frame 0xfffffe0020f2b8b0 dofilewrite() at dofilewrite+0xfd/frame 0xfffffe0020f2b910 kern_writev() at kern_writev+0x66/frame 0xfffffe0020f2b950 sys_writev() at sys_writev+0x50/frame 0xfffffe0020f2b980 amd64_syscall() at amd64_syscall+0x436/frame 0xfffffe0020f2bab0 fast_syscall_common() at fast_syscall_common+0x101/frame 0xfffffe0020f2bab0 --- syscall (198, FreeBSD ELF64, nosys), rip = 0x4131ba, rsp = 0x7fffdffdcf38, rbp = 0x3 --- KDB: enter: panic [ thread pid 2207 tid 101020 ] Stopped at kdb_enter+0x6a: movq $0,kdb_why