panic: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/kern_synch.c", line 944
Starting stack trace...
panic(ffffffff8343e57f) at panic+0x1d0 sys/kern/subr_prf.c:229
__assert(ffffffff833e7f5a,ffffffff833ec766,3b0,ffffffff833ec7ae) at __assert+0x29
refcnt_finalize(ffff8000ffff5148,ffffffff833335f3) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:945
pppx_if_destroy(205b9a,ffff8000ffff5140) at pppx_if_destroy+0x3d sys/net/if_pppx.c:806
pppxclose(205b9a,1,2000,ffff800038cba7e0) at pppxclose+0xa0 sys/net/if_pppx.c:553
spec_close(ffff80003c578330) at spec_close+0x412
VOP_CLOSE(fffffd805f946558,1,fffffd807f7d2270,ffff800038cba7e0) at VOP_CLOSE+0x133 sys/kern/vfs_vops.c:156
vn_closefile(fffffd806bcc9738,ffff800038cba7e0) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:292 [inline]
vn_closefile(fffffd806bcc9738,ffff800038cba7e0) at vn_closefile+0x12b sys/kern/vfs_vnops.c:615
fdrop(fffffd806bcc9738,ffff800038cba7e0) at fdrop+0x126 sys/kern/kern_descrip.c:1265
closef(fffffd806bcc9738,ffff800038cba7e0) at closef+0x192 sys/kern/kern_descrip.c:1249
fdfree(ffff800038cba7e0) at fdfree+0x116 sys/kern/kern_descrip.c:1181
exit1(ffff800038cba7e0,0,0,1) at exit1+0x57f sys/kern/kern_exit.c:214
sys_exit(ffff800038cba7e0,ffff80003c5786a0,ffff80003c5785f0) at sys_exit+0x1a
syscall(ffff80003c5786a0) at syscall+0xb08 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80003c5786a0) at syscall+0xb08 sys/arch/amd64/amd64/trap.c:577
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x7b3569c04250, count: 242
End of stack trace.