panic: kernfs.Dentry.DecRef() called without holding a reference

goroutine 6554 [running]:
panic({0x172f380, 0x1b224a0})
	GOROOT/src/runtime/panic.go:941 +0x397 fp=0xc000bb0c98 sp=0xc000bb0bd8 pc=0x438397
gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs.(*Dentry).decRefLocked(0xc007844e10, {0x1b3c770, 0xc002171500})
	pkg/sentry/fsimpl/kernfs/kernfs.go:302 +0x109 fp=0xc000bb0cc8 sp=0xc000bb0c98 pc=0xa55929
gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs.(*Dentry).releaseKeptDentriesLocked(0xc007844e10, {0x1b3c770, 0xc002171500})
	pkg/sentry/fsimpl/kernfs/filesystem.go:282 +0x10a fp=0xc000bb0da8 sp=0xc000bb0cc8 pc=0xa41d0a
gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs.(*Dentry).releaseKeptDentriesLocked(0xc007844cf0, {0x1b3c770, 0xc002171500})
	pkg/sentry/fsimpl/kernfs/filesystem.go:293 +0x33f fp=0xc000bb0e88 sp=0xc000bb0da8 pc=0xa41f3f
gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs.(*Filesystem).Release(0xc0010ad7a0, {0x1b3c770, 0xc002171500})
	pkg/sentry/fsimpl/kernfs/filesystem.go:267 +0xa6 fp=0xc000bb0ec0 sp=0xc000bb0e88 pc=0xa41b26
gvisor.dev/gvisor/pkg/sentry/fsimpl/cgroupfs.(*filesystem).Release(0xc0010ad7a0, {0x1b3c770, 0xc002171500})
	pkg/sentry/fsimpl/cgroupfs/cgroupfs.go:474 +0x219 fp=0xc000bb0f18 sp=0xc000bb0ec0 pc=0x11e3db9
gvisor.dev/gvisor/pkg/sentry/vfs.(*Filesystem).DecRef.func1()
	pkg/sentry/vfs/filesystem.go:81 +0x117 fp=0xc000bb0f68 sp=0xc000bb0f18 pc=0x9733d7
gvisor.dev/gvisor/pkg/sentry/vfs.(*FilesystemRefs).DecRef(0xc0010ad7a0, 0xc000bb0fd8)
	bazel-out/k8-fastbuild-ST-3dcbe13c9b87/bin/pkg/sentry/vfs/filesystem_refs.go:131 +0xb2 fp=0xc000bb0fc8 sp=0xc000bb0f68 pc=0x973ef2
gvisor.dev/gvisor/pkg/sentry/vfs.(*Filesystem).DecRef(0xc0010ad7a0, {0x1b3c770, 0xc002171500})
	pkg/sentry/vfs/filesystem.go:77 +0x87 fp=0xc000bb1008 sp=0xc000bb0fc8 pc=0x973287
gvisor.dev/gvisor/pkg/sentry/vfs.(*Mount).destroy(0xc003ac5080, {0x1b3c770, 0xc002171500})
	pkg/sentry/vfs/mount.go:926 +0x1b4 fp=0xc000bb1060 sp=0xc000bb1008 pc=0x9823f4
gvisor.dev/gvisor/pkg/sentry/vfs.(*Mount).DecRef(0xc003ac5080, {0x1b3c770, 0xc002171500})
	pkg/sentry/vfs/mount.go:910 +0xca fp=0xc000bb1090 sp=0xc000bb1060 pc=0x9821ea
gvisor.dev/gvisor/pkg/sentry/vfs.VirtualDentry.DecRef({0xc003ac5080?, 0xc007844cf0?}, {0x1b3c770, 0xc002171500})
	pkg/sentry/vfs/vfs.go:927 +0x7e fp=0xc000bb10c8 sp=0xc000bb1090 pc=0x99999e
gvisor.dev/gvisor/pkg/sentry/vfs.(*VirtualFilesystem).UmountAt.func1()
	pkg/sentry/vfs/mount.go:653 +0x74 fp=0xc000bb1110 sp=0xc000bb10c8 pc=0x981014
runtime.deferreturn()
	GOROOT/src/runtime/panic.go:436 +0x33 fp=0xc000bb1150 sp=0xc000bb1110 pc=0x4374b3
gvisor.dev/gvisor/pkg/sentry/vfs.(*VirtualFilesystem).UmountAt(0xc0001ac1d0, {0x1b3c770, 0xc002171500}, 0xc001505440, 0xc003f04300?, 0xc000bb1424)
	pkg/sentry/vfs/mount.go:739 +0xcfe fp=0xc000bb1398 sp=0xc000bb1150 pc=0x980b9e
gvisor.dev/gvisor/pkg/sentry/syscalls/linux.Umount2(0xc002171500, {{0x7f5398ff4580}, {0xa}, {0x7f5398ff458c}, {0x564c817a27a3}, {0xffffffff}, {0x7f5398ff4350}})
	pkg/sentry/syscalls/linux/sys_mount.go:171 +0x3a5 fp=0xc000bb15b0 sp=0xc000bb1398 pc=0xefbcc5
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0xc002171500, 0xa6, {{0x7f5398ff4580}, {0xa}, {0x7f5398ff458c}, {0x564c817a27a3}, {0xffffffff}, {0x7f5398ff4350}})
	pkg/sentry/kernel/task_syscall.go:142 +0xab8 fp=0xc000bb19f8 sp=0xc000bb15b0 pc=0xce1278
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0xc002171500, 0x1?, {{0x7f5398ff4580}, {0xa}, {0x7f5398ff458c}, {0x564c817a27a3}, {0xffffffff}, {0x7f5398ff4350}})
	pkg/sentry/kernel/task_syscall.go:322 +0x8e fp=0xc000bb1a98 sp=0xc000bb19f8 pc=0xce340e
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0xc003cfa870?, 0x46fdec?, {{0x7f5398ff4580}, {0xa}, {0x7f5398ff458c}, {0x564c817a27a3}, {0xffffffff}, {0x7f5398ff4350}})
	pkg/sentry/kernel/task_syscall.go:282 +0xc5 fp=0xc000bb1b10 sp=0xc000bb1a98 pc=0xce2ce5
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0xc002171500)
	pkg/sentry/kernel/task_syscall.go:257 +0x53b fp=0xc000bb1c38 sp=0xc000bb1b10 pc=0xce27db
gvisor.dev/gvisor/pkg/sentry/kernel.(*runApp).execute(0xc002171500?, 0xc002171500)
	pkg/sentry/kernel/task_run.go:253 +0x1e2b fp=0xc000bb1ec0 sp=0xc000bb1c38 pc=0xccbdab
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0xc002171500, 0xa9e)
	pkg/sentry/kernel/task_run.go:94 +0x2c2 fp=0xc000bb1fb0 sp=0xc000bb1ec0 pc=0xcc95c2
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start.func1()
	pkg/sentry/kernel/task_start.go:378 +0x48 fp=0xc000bb1fe0 sp=0xc000bb1fb0 pc=0xcde988
runtime.goexit()
	src/runtime/asm_amd64.s:1571 +0x1 fp=0xc000bb1fe8 sp=0xc000bb1fe0 pc=0x46e1c1
created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start
	pkg/sentry/kernel/task_start.go:378 +0x1d0