syzbot

panic: interface conversion: vfs.DentryImpl is *tmpfs.dentry, not *kernfs.Dentry

goroutine 180 [running]:
panic({0x31eb00, 0xc00064ed80})
	GOROOT/src/runtime/panic.go:987 +0x3ba fp=0xc0006c0ea8 sp=0xc0006c0de8 pc=0x118b57a
runtime.panicdottypeE(...)
	GOROOT/src/runtime/iface.go:262
runtime.panicdottypeI(0xc000898338?, 0x473560, 0x36bde0)
	GOROOT/src/runtime/iface.go:272 +0x7c fp=0xc0006c0ed0 sp=0xc0006c0ea8 pc=0x115ea5c
gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs.(*Filesystem).LinkAt(0xc0001d52c0, {0x750278, 0xc000957500}, 0xc0008e8480, {0xc0007ac300?, 0xc000168aa0?})
	pkg/sentry/fsimpl/kernfs/filesystem.go:367 +0xce5 fp=0xc0006c1178 sp=0xc0006c0ed0 pc=0x17c6c25
gvisor.dev/gvisor/pkg/sentry/fsimpl/proc.(*filesystem).LinkAt(0xc0001d52c0, {0x750278, 0xc000957500}, 0x1c87127?, {0xc0007ac300?, 0xc000168aa0?})
	<autogenerated>:1 +0x8a fp=0xc0006c11e0 sp=0xc0006c1178 pc=0x1df918a
gvisor.dev/gvisor/pkg/sentry/vfs.(*VirtualFilesystem).LinkAt(0xc000957500?, {0x750278, 0xc000957500}, 0xc0008982d0?, 0xc00078aa00?, 0xc0006c1490)
	pkg/sentry/vfs/vfs.go:296 +0x402 fp=0xc0006c1298 sp=0xc0006c11e0 pc=0x1715062
gvisor.dev/gvisor/pkg/sentry/syscalls/linux.linkat(0xc000957500, 0x11c5737?, 0x2658f24?, 0x1?, 0x11c426c?, 0x0)
	pkg/sentry/syscalls/linux/sys_file.go:1029 +0x4aa fp=0xc0006c1540 sp=0xc0006c1298 pc=0x1ca70ca
gvisor.dev/gvisor/pkg/sentry/syscalls/linux.Linkat(0x0?, {{0x3}, {0x20000000}, {0x4}, {0x20000040}, {0x0}, {0x0}})
	pkg/sentry/syscalls/linux/sys_file.go:998 +0xf1 fp=0xc0006c15c0 sp=0xc0006c1540 pc=0x1ca6bd1
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0xc000957500, 0x109, {{0x3}, {0x20000000}, {0x4}, {0x20000040}, {0x0}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:142 +0xab8 fp=0xc0006c19d8 sp=0xc0006c15c0 pc=0x1a94358
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0xc000957500, 0x1?, {{0x3}, {0x20000000}, {0x4}, {0x20000040}, {0x0}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:322 +0x8e fp=0xc0006c1a78 sp=0xc0006c19d8 pc=0x1a964ae
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0xc0008bc000?, 0x115a81d?, {{0x3}, {0x20000000}, {0x4}, {0x20000040}, {0x0}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:282 +0xc5 fp=0xc0006c1af0 sp=0xc0006c1a78 pc=0x1a95d85
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0xc000957500)
	pkg/sentry/kernel/task_syscall.go:257 +0x53b fp=0xc0006c1c18 sp=0xc0006c1af0 pc=0x1a9587b
gvisor.dev/gvisor/pkg/sentry/kernel.(*runApp).execute(0xc000957500?, 0xc000957500)
	pkg/sentry/kernel/task_run.go:259 +0x2094 fp=0xc0006c1ec0 sp=0xc0006c1c18 pc=0x1a7e6b4
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0xc000957500, 0xf)
	pkg/sentry/kernel/task_run.go:94 +0x2cc fp=0xc0006c1fb0 sp=0xc0006c1ec0 pc=0x1a7bc4c
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start.func1()
	pkg/sentry/kernel/task_start.go:377 +0x48 fp=0xc0006c1fe0 sp=0xc0006c1fb0 pc=0x1a91a48
runtime.goexit()
	src/runtime/asm_amd64.s:1594 +0x1 fp=0xc0006c1fe8 sp=0xc0006c1fe0 pc=0x11c2601
created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start
	pkg/sentry/kernel/task_start.go:377 +0x1da