syzbot

witness: lock order reversal:
 1st 0xffff800010fdc1f8 sbufsnd (&so->so_snd.sb_lock)
 2nd 0xfffffc006c1fc5b0 inode (&ip->i_lock)
lock order [1] sbufsnd (&so->so_snd.sb_lock) -> [2] inode (&ip->i_lock)
lock order data 0xffffffff83518ef8 -> 0xffffffff8348dc26 is missing
lock order [2] inode (&ip->i_lock) -> [3] sbufrcv (&so->so_rcv.sb_lock)
#0  rw_do_enter_write+0xba sys/kern/kern_rwlock.c:234
#1  sblock+0xb6 sys/kern/uipc_socket2.c:536
#2  soreceive+0x27d sys/kern/uipc_socket.c:890
#3  fifo_read+0x117 sys/miscfs/fifofs/fifo_vnops.c:264
#4  VOP_READ+0x101 sys/kern/vfs_vops.c:227
#5  vn_rdwr+0x15b sys/kern/vfs_vnops.c:-1
#6  vndsetcred+0xa1 sys/dev/vnd.c:685
#7  vndioctl+0xdfc sys/dev/vnd.c:486
#8  VOP_IOCTL+0xac sys/kern/vfs_vops.c:264
#9  vn_ioctl+0xf8 sys/kern/vfs_vnops.c:537
#10 sys_ioctl+0x674 sys/kern/sys_generic.c:-1
#11 syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline]
#11 syscall+0xbd4 sys/arch/amd64/amd64/trap.c:783
#12 Xsyscall+0x128
lock order [3] sbufrcv (&so->so_rcv.sb_lock) -> [1] sbufsnd (&so->so_snd.sb_lock)
#0  rw_do_enter_write+0xba sys/kern/kern_rwlock.c:234
#1  sblock+0xb6 sys/kern/uipc_socket2.c:536
#2  sosplice+0x246 sys/kern/uipc_socket.c:1326
#3  sys_setsockopt+0x2ba sys/kern/uipc_syscalls.c:1226
#4  syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline]
#4  syscall+0xbd4 sys/arch/amd64/amd64/trap.c:783
#5  Xsyscall+0x128
Stopped at      db_enter+0x25:  addq    $0x8,%rsp
ddb{1}> 
ddb{1}> set $lines = 0
ddb{1}> set $maxwidth = 0
ddb{1}> show panic
the kernel did not panic
ddb{1}> trace
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
witness_checkorder(fffffc006c1fc5b0,9,0) at witness_checkorder+0x10d1 sys/kern/subr_witness.c:-1
rw_do_enter_write(fffffc006c1fc598,1) at rw_do_enter_write+0xba sys/kern/kern_rwlock.c:234
rrw_enter(fffffc006c1fc598,1) at rrw_enter+0xc6 sys/kern/kern_rwlock.c:621
VOP_LOCK(fffffc0067775890,2001) at VOP_LOCK+0xbd sys/kern/vfs_vops.c:527
vn_lock(fffffc0067775890,2001) at vn_lock+0xa4 sys/kern/vfs_vnops.c:576
vfs_lookup(ffff80002a27bc10) at vfs_lookup+0x12b sys/kern/vfs_lookup.c:431
namei(ffff80002a27bc10) at namei+0x7c5 sys/kern/vfs_lookup.c:250
unp_connect(ffff800010fdc010,fffffc0064003e00,ffff80002a212010) at unp_connect+0x29d sys/kern/uipc_usrreq.c:872
uipc_dgram_send(ffff800010fdc010,fffffc0064001f00,fffffc0064003e00,0) at uipc_dgram_send+0x163 sys/kern/uipc_usrreq.c:609
sosend(ffff800010fdc010,fffffc0064003e00,ffff80002a27be98,0,0,0) at sosend+0x804 sys/kern/uipc_socket.c:-1
sendit(ffff80002a212010,6,ffff80002a27c018,0,ffff80002a27c0d0) at sendit+0x5a5 sys/kern/uipc_syscalls.c:785
sys_sendmsg(ffff80002a212010,ffff80002a27c180,ffff80002a27c0d0) at sys_sendmsg+0x246 sys/kern/uipc_syscalls.c:603
syscall(ffff80002a27c180) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80002a27c180) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x5a3482eb240, count: -15
ddb{1}> show registers
rdi                                0
rsi                                0
rbp               0xffff80002a27b880
rbx                                0
rdx                                0
rcx               0xffff80002a212010
rax               0xffff80002998dff0
r8                0xffff80002a27b760
r9                0x8080808080808080
r10               0x488a1240dec95f88
r11               0x6c65742220c20938
r12               0xfffffc00040c28c0
r13               0xfffffc00048aaf00
r14                              0x3
r15               0xffffffff83524398    substchar+0x5d01
rip               0xffffffff832e3685    db_enter+0x25
cs                               0x8
rflags                         0x246
rsp               0xffff80002a27b870
ss                              0x10
db_enter+0x25:  addq    $0x8,%rsp
ddb{1}> show proc
PROC (syz-executor) tid=191623 pid=63174 tcnt=2 stat=onproc
    flags process=10<SUGID> proc=4000000<THREAD>
    runpri=32, usrpri=50, slppri=32, nice=20
    wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0
    forw=0xffffffffffffffff, list=0xffff80002a212a70,0xffff80002a213ca8
    process=0xffff80003c3ca6a0 user=0xffff80002a277000, vmspace=0xfffffc006c522010
    estcpu=36, cpticks=0, pctcpu=0.0, user=0, sys=0, intr=0
ddb{1}> ps
   PID     TID   PPID    UID  S       FLAGS  WAIT          COMMAND
 63174  282150  16034  60929  2        0x10                syz-executor
*63174  191623  16034  60929  7   0x4000010                syz-executor
 46810  321827  61240      0  7           0                syz-executor
 46810  193449  61240      0  2   0x4000000                syz-executor
 60995   81509  82754      0  2           0                syz-executor
 22446  232218  41333      0  2           0                syz-executor
 22446  357200  41333      0  3   0x4000080  fsleep        syz-executor
 14257   84268  24229      0  2         0x2                syz-executor
 84483  440647      1      0  3    0x100083  ttyin         getty
 26188  122972  24229      0  3        0x82  piperd        syz-executor
 33738  358423  24229      0  3        0x82  piperd        syz-executor
 18750  143350  24229      0  3        0x82  piperd        syz-executor
 16034  316549  24229      0  3        0x82  nanoslp       syz-executor
 61240  280073  24229      0  3        0x82  nanoslp       syz-executor
 82754  353413  24229      0  3        0x82  nanoslp       syz-executor
 41333   61776  24229      0  3        0x82  nanoslp       syz-executor
 24229  170201      1      0  2         0x2                syz-executor
 90635  462008      0      0  3     0x14200  bored         smr
 56848  112255      0      0  2     0x14200                zerothread
 96051   15795      0      0  3     0x14200  aiodoned      aiodoned
 87950  266892      0      0  3     0x14200  syncer        update
 23060  510241      0      0  3     0x14200  cleaner       cleaner
 17153  481756      0      0  3     0x14200  reaper        reaper
 53544  126542      0      0  3     0x14200  pgdaemon      pagedaemon
  8086   56710      0      0  3     0x14200  bored         viomb
 42568  405887      0      0  3  0x40014200  acpi0         acpi0
 35790  457419      0      0  3  0x40014200                idle1
 21771  312859      0      0  3     0x14200  bored         softnet1
 34462   96672      0      0  2     0x14200                softnet0
 17443  122829      0      0  3     0x14200  bored         systqmp
 57721  316767      0      0  3     0x14200  bored         systq
 18815  430120      0      0  3     0x14200  tmoslp        softclockmp
 73938  390309      0      0  3  0x40014200  tmoslp        softclock
  8855  518124      0      0  3  0x40014200                idle0
     1   12412      0      0  3        0x82  wait          init
     0       0     -1      0  3  0x10010200  scheduler     swapper
ddb{1}>