kern.securelevel: 0 -> 1
creating runtime link editor directory cache.
preserving editor files.
starting network daemons: sshd.
starting local daemons:.
Wed Sep 18 11:17:52 PDT 2019

OpenBSD/amd64 (ci-openbsd-multicore-4.c.syzkaller.internal) (tty00)

Warning: Permanently added '10.128.1.19' (ECDSA) to the list of known hosts.
2019/09/18 11:18:29 parsed 1 programs
2019/09/18 11:18:35 executed programs: 0
2019/09/18 11:18:40 executed programs: 258
login: panic: pool_cache_item_magic_check: mbufpl cpu free list modified: item addr 0xfffffd806d732400+16 0x0!=0xf9ef81fdec24a3af

Stopped at      db_enter+0x18:  addq    $0x8,%rsp

    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND

 343728  60677      0     0x14000      0x200    1  reaper

*209997  87037      0     0x14000 0x40000200    0K softclock

db_enter() at db_enter+0x18

panic() at panic+0x15c

pool_cache_get(ffffffff82658ba8) at pool_cache_get+0x323

pool_get() at pool_get+0x91

m_get(2,1) at m_get+0x4c

mld6_sendpkt(ffff800000a5d100,83,0) at mld6_sendpkt+0xaf

mld6_fasttimeo() at mld6_fasttimeo+0x162

pffasttimo(ffffffff8254c978) at pffasttimo+0x85

timeout_run(ffffffff8254c978) at timeout_run+0xc4

softclock_thread(ffff800020a10000) at softclock_thread+0x16a

end trace frame: 0x0, count: 5

https://www.openbsd.org/ddb.html describes the minimum info required in bug

reports.  Insufficient info makes it difficult to find and fix bugs.

ddb{0}> 

ddb{0}> set $lines = 0

ddb{0}> set $maxwidth = 0

ddb{0}> show panic

pool_cache_item_magic_check: mbufpl cpu free list modified: item addr 0xfffffd806d732400+16 0x0!=0xf9ef81fdec24a3af

ddb{0}> trace

db_enter() at db_enter+0x18

panic() at panic+0x15c

pool_cache_get(ffffffff82658ba8) at pool_cache_get+0x323

pool_get() at pool_get+0x91

m_get(2,1) at m_get+0x4c

mld6_sendpkt(ffff800000a5d100,83,0) at mld6_sendpkt+0xaf

mld6_fasttimeo() at mld6_fasttimeo+0x162

pffasttimo(ffffffff8254c978) at pffasttimo+0x85

timeout_run(ffffffff8254c978) at timeout_run+0xc4

softclock_thread(ffff800020a10000) at softclock_thread+0x16a

end trace frame: 0x0, count: -10

ddb{0}> show registers

rdi                                0

rsi                              0x1

rbp               0xffff800020a25750

rbx               0xffff800020a25800

rdx                             0x8b

rcx                              0x2

rax                              0x1

r8                0xffffffff81ebdc8f    kprintf+0x16f

r9                               0x1

r10               0x6d5e77c31ce9713f

r11               0xe4fd54fa694ca076

r12                     0x3000000008

r13               0xffff800020a25760

r14                            0x100

r15                              0x1

rip               0xffffffff81c5afd8    db_enter+0x18

cs                               0x8

rflags                         0x246

rsp               0xffff800020a25740

ss                              0x10

db_enter+0x18:  addq    $0x8,%rsp

ddb{0}> show proc

PROC (softclock) pid=209997 stat=onproc

    flags process=14000<NOZOMBIE,SYSTEM> proc=40000200<SYSTEM,CPUPEG>

    pri=0, usrpri=50, nice=20

    forw=0xffffffffffffffff, list=0xffff800020a104f0,0xffff800020a10288

    process=0xffff800020a12700 user=0xffff800020a20000, vmspace=0xffffffff82626ed8

    estcpu=0, cpticks=1, pctcpu=0.0

    user=0, sys=1, intr=0

ddb{0}>