panic: kmmaplk rwlock ADDR: enter read deadlock

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c9c58e023502 Stop printing the riscv,isa string; our code ..
git tree: openbsd
console output: https://syzkaller.appspot.com/x/log.txt?x=12474dda580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1bc15e68cd2a49e5
dashboard link: https://syzkaller.appspot.com/bug?extid=1e80f455c0ca2c6a3b54

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a873622b0a9c/disk-c9c58e02.raw.xz
bsd.gdb: https://storage.googleapis.com/syzbot-assets/ae07f90a93ec/bsd-c9c58e02.gdb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/737788d6e825/kernel-c9c58e02.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1e80f4...@syzkaller.appspotmail.com

panic: kmmaplk rwlock 0xffffffff83997b10: enter read deadlock
Stopped at db_enter+0x25: addq $0x8,%rsp
TID PID UID PRFLAGS PFLAGS CPU COMMAND
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff833c3f18) at panic+0x1cf sys/kern/subr_prf.c:198
rw_do_enter_read(ffffffff83997b10,0) at rw_do_enter_read+0x435 sys/kern/kern_rwlock.c:379
uvmfault_lookup(ffff800033cd8680,0) at uvmfault_lookup+0x122 sys/uvm/uvm_fault.c:1880
uvm_fault_check(ffff800033cd8680,ffff800033cd86b8,ffff800033cd86f0,0) at uvm_fault_check+0x4f sys/uvm/uvm_fault.c:693
uvm_fault(ffffffff83997a28,ffff800029ef5000,0,1) at uvm_fault+0xe6 sys/uvm/uvm_fault.c:627
kpageflttrap(ffff800033cd8820,ffff800029ef5020) at kpageflttrap+0x2d1 sys/arch/amd64/amd64/trap.c:-1
kerntrap(ffff800033cd8820) at kerntrap+0x18a sys/arch/amd64/amd64/trap.c:528
alltraps_kern_meltdown() at alltraps_kern_meltdown+0x7b
pvclock_tick(ffff800000025800) at pvclock_tick+0x54 sys/dev/pv/pvclock.c:374
timeout_run(ffffffff8382b840,ffff800000025938) at timeout_run+0xf3 sys/kern/kern_timeout.c:-1
softclock_process_tick_timeout(ffff800000025938,0) at softclock_process_tick_timeout+0x230 sys/kern/kern_timeout.c:756
softclock(0) at softclock+0x152 sys/kern/kern_timeout.c:788
softintr_dispatch(0) at softintr_dispatch+0xf9 sys/kern/kern_softintr.c:87
end trace frame: 0xffff800033cd8aa0, count: 0
https://www.openbsd.org/ddb.html describes the minimum info required in bug
reports. Insufficient info makes it difficult to find and fix bugs.


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup