login: witness: userret: returning with the following locks held: exclusive rrwlock inode r = 0 (0xfffffd806d1614e8) locked @ /syzkaller/managers/multicore/kernel/sys/ufs/ufs/ufs_vnops.c:1547 panic: witness_warn Stopped at db_enter+0x18: addq $0x8,%rsp TID PID UID PRFLAGS PFLAGS CPU COMMAND *125366 17855 0 0 0x4000000 0 syz-executor1 16712 53164 0 0x2 0x480 1 syz-executor0 db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:399 panic() at panic+0x16c sys/kern/subr_prf.c:208 witness_warn(fb8bf876291c9110,0,ffff800020b92bd0) at witness_warn+0x700 witness_debugger sys/kern/subr_witness.c:2549 [inline] witness_warn(fb8bf876291c9110,0,ffff800020b92bd0) at witness_warn+0x700 sys/kern/subr_witness.c:1465 userret(d9268db41bd3acfc) at userret+0x361 sys/kern/kern_sig.c:1899 syscall(5f36a0049d8a39f5) at syscall+0x680 mi_syscall_return sys/sys/syscall_mi.h:122 [inline] syscall(5f36a0049d8a39f5) at syscall+0x680 sys/arch/amd64/amd64/trap.c:605 Xsyscall(6,5,c,0,3,5c2ef49c0d8) at Xsyscall+0x128 end of kernel end trace frame: 0x5c57b1831f0, count: 9 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}> show panic witness_warn ddb{0}> trace db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:399 panic() at panic+0x16c sys/kern/subr_prf.c:208 witness_warn(fb8bf876291c9110,0,ffff800020b92bd0) at witness_warn+0x700 witness_debugger sys/kern/subr_witness.c:2549 [inline] witness_warn(fb8bf876291c9110,0,ffff800020b92bd0) at witness_warn+0x700 sys/kern/subr_witness.c:1465 userret(d9268db41bd3acfc) at userret+0x361 sys/kern/kern_sig.c:1899 syscall(5f36a0049d8a39f5) at syscall+0x680 mi_syscall_return sys/sys/syscall_mi.h:122 [inline] syscall(5f36a0049d8a39f5) at syscall+0x680 sys/arch/amd64/amd64/trap.c:605 Xsyscall(6,5,c,0,3,5c2ef49c0d8) at Xsyscall+0x128 end of kernel end trace frame: 0x5c57b1831f0, count: -6 ddb{0}> show registers rdi 0 rsi 0x1 rbp 0xffff800020c93670 rbx 0xffff800020c93710 rdx 0xffffffff81f30ae0 cy_pio_rec+0x9b0 rcx 0x201 rax 0x1 r8 0xffffffff815db184 kprintf+0x174 r9 0x1 r10 0xca293be8dba7cc45 r11 0xff73c1f0f18a72a5 r12 0x3000000008 r13 0xffff800020c93680 r14 0x100 r15 0x1 rip 0xffffffff81565418 db_enter+0x18 cs 0x8 rflags 0x246 rsp 0xffff800020c93660 ss 0 db_enter+0x18: addq $0x8,%rsp ddb{0}> show proc PROC (syz-executor1) pid=125366 stat=onproc flags process=0 proc=4000000 pri=32, usrpri=86, nice=20 forw=0xffffffffffffffff, list=0xffff800020b75778,0xffff800020b932e8 process=0xffff800020b95a50 user=0xffff800020c8e000, vmspace=0xfffffd807f00db40 estcpu=36, cpticks=2, pctcpu=0.0 user=0, sys=2, intr=0 ddb{0}> ps PID TID PPID UID S FLAGS WAIT COMMAND 9581 450974 53164 0 2 0x480 syz-executor0 9581 64978 53164 0 3 0x4000080 fsleep syz-executor0 9581 265030 53164 0 3 0x4000080 fsleep syz-executor0 17855 255359 86674 0 2 0 syz-executor1 17855 165156 86674 0 3 0x4000080 fsleep syz-executor1 *17855 125366 86674 0 7 0x4000000 syz-executor1 17855 147365 86674 0 2 0x4000000 syz-executor1 86674 499944 75729 0 2 0x2 syz-executor1 53164 16712 75729 0 7 0x482 syz-executor0 75729 330768 19443 0 3 0x82 kqread syz-execprog 75729 40044 19443 0 3 0x4000082 thrsleep syz-execprog 75729 520267 19443 0 3 0x4000082 thrsleep syz-execprog 75729 249507 19443 0 3 0x4000082 thrsleep syz-execprog 75729 302126 19443 0 3 0x4000082 thrsleep syz-execprog 75729 119279 19443 0 3 0x4000082 thrsleep syz-execprog 75729 193024 19443 0 3 0x4000082 thrsleep syz-execprog 75729 388950 19443 0 3 0x4000082 thrsleep syz-execprog 75729 82517 19443 0 3 0x4000082 thrsleep syz-execprog 19443 28616 97012 0 3 0x10008a pause ksh 97012 522064 88707 0 3 0x92 select sshd 29196 165726 1 0 3 0x100083 ttyin getty 88707 422804 1 0 3 0x80 select sshd 83669 441995 49813 73 3 0x100010 ffs_fsync syslogd 49813 147981 1 0 3 0x100082 netio syslogd 34301 111569 1 77 3 0x100090 poll dhclient 15413 105099 1 0 3 0x80 poll dhclient 54494 301167 0 0 3 0x14200 pgzero zerothread 58457 216759 0 0 3 0x14200 aiodoned aiodoned 1046 373921 0 0 3 0x14200 syncer update 52433 241655 0 0 3 0x14200 cleaner cleaner 22677 47926 0 0 3 0x14200 reaper reaper 62026 492090 0 0 3 0x14200 pgdaemon pagedaemon 87411 498852 0 0 3 0x14200 bored crynlk 38598 369469 0 0 3 0x14200 bored crypto 82037 142597 0 0 3 0x40014200 acpi0 acpi0 58826 71575 0 0 3 0x40014200 idle1 22540 302360 0 0 3 0x14200 bored softnet 74250 305226 0 0 3 0x14200 bored systqmp 92981 289350 0 0 3 0x14200 bored systq 23221 130 0 0 3 0x40014200 bored softclock 6155 158173 0 0 3 0x40014200 idle0 1 244991 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper ddb{0}>