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

goroutine 6585 [running]:
panic({0x172f380, 0x1b224a0})
	GOROOT/src/runtime/panic.go:941 +0x397 fp=0xc001d82c98 sp=0xc001d82bd8 pc=0x438397
gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs.(*Dentry).decRefLocked(0xc0007a8000, {0x1b3c770, 0xc002894a80})
	pkg/sentry/fsimpl/kernfs/kernfs.go:302 +0x109 fp=0xc001d82cc8 sp=0xc001d82c98 pc=0xa55929
gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs.(*Dentry).releaseKeptDentriesLocked(0xc0007a8000, {0x1b3c770, 0xc002894a80})
	pkg/sentry/fsimpl/kernfs/filesystem.go:282 +0x10a fp=0xc001d82da8 sp=0xc001d82cc8 pc=0xa41d0a
gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs.(*Dentry).releaseKeptDentriesLocked(0xc0037aba70, {0x1b3c770, 0xc002894a80})
	pkg/sentry/fsimpl/kernfs/filesystem.go:293 +0x33f fp=0xc001d82e88 sp=0xc001d82da8 pc=0xa41f3f
gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs.(*Filesystem).Release(0xc0005e1440, {0x1b3c770, 0xc002894a80})
	pkg/sentry/fsimpl/kernfs/filesystem.go:267 +0xa6 fp=0xc001d82ec0 sp=0xc001d82e88 pc=0xa41b26
gvisor.dev/gvisor/pkg/sentry/fsimpl/cgroupfs.(*filesystem).Release(0xc0005e1440, {0x1b3c770, 0xc002894a80})
	pkg/sentry/fsimpl/cgroupfs/cgroupfs.go:474 +0x219 fp=0xc001d82f18 sp=0xc001d82ec0 pc=0x11e3db9
gvisor.dev/gvisor/pkg/sentry/vfs.(*Filesystem).DecRef.func1()
	pkg/sentry/vfs/filesystem.go:81 +0x117 fp=0xc001d82f68 sp=0xc001d82f18 pc=0x9733d7
gvisor.dev/gvisor/pkg/sentry/vfs.(*FilesystemRefs).DecRef(0xc0005e1440, 0xc001d82fd8)
	bazel-out/k8-fastbuild-ST-3dcbe13c9b87/bin/pkg/sentry/vfs/filesystem_refs.go:131 +0xb2 fp=0xc001d82fc8 sp=0xc001d82f68 pc=0x973ef2
gvisor.dev/gvisor/pkg/sentry/vfs.(*Filesystem).DecRef(0xc0005e1440, {0x1b3c770, 0xc002894a80})
	pkg/sentry/vfs/filesystem.go:77 +0x87 fp=0xc001d83008 sp=0xc001d82fc8 pc=0x973287
gvisor.dev/gvisor/pkg/sentry/vfs.(*Mount).destroy(0xc00401cb00, {0x1b3c770, 0xc002894a80})
	pkg/sentry/vfs/mount.go:926 +0x1b4 fp=0xc001d83060 sp=0xc001d83008 pc=0x9823f4
gvisor.dev/gvisor/pkg/sentry/vfs.(*Mount).DecRef(0xc00401cb00, {0x1b3c770, 0xc002894a80})
	pkg/sentry/vfs/mount.go:910 +0xca fp=0xc001d83090 sp=0xc001d83060 pc=0x9821ea
gvisor.dev/gvisor/pkg/sentry/vfs.VirtualDentry.DecRef({0xc00401cb00?, 0xc0037aba70?}, {0x1b3c770, 0xc002894a80})
	pkg/sentry/vfs/vfs.go:927 +0x7e fp=0xc001d830c8 sp=0xc001d83090 pc=0x99999e
gvisor.dev/gvisor/pkg/sentry/vfs.(*VirtualFilesystem).UmountAt.func1()
	pkg/sentry/vfs/mount.go:653 +0x74 fp=0xc001d83110 sp=0xc001d830c8 pc=0x981014
runtime.deferreturn()
	GOROOT/src/runtime/panic.go:436 +0x33 fp=0xc001d83150 sp=0xc001d83110 pc=0x4374b3
gvisor.dev/gvisor/pkg/sentry/vfs.(*VirtualFilesystem).UmountAt(0xc00058e1d0, {0x1b3c770, 0xc002894a80}, 0xc00407ab40, 0xc00508eb00?, 0xc001d83424)
	pkg/sentry/vfs/mount.go:739 +0xcfe fp=0xc001d83398 sp=0xc001d83150 pc=0x980b9e
gvisor.dev/gvisor/pkg/sentry/syscalls/linux.Umount2(0xc002894a80, {{0x7fdf15186580}, {0xa}, {0x7fdf1518658c}, {0x55c48851b7a3}, {0xffffffff}, {0x7fdf15186350}})
	pkg/sentry/syscalls/linux/sys_mount.go:171 +0x3a5 fp=0xc001d835b0 sp=0xc001d83398 pc=0xefbcc5
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0xc002894a80, 0xa6, {{0x7fdf15186580}, {0xa}, {0x7fdf1518658c}, {0x55c48851b7a3}, {0xffffffff}, {0x7fdf15186350}})
	pkg/sentry/kernel/task_syscall.go:142 +0xab8 fp=0xc001d839f8 sp=0xc001d835b0 pc=0xce1278
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0xc002894a80, 0x1?, {{0x7fdf15186580}, {0xa}, {0x7fdf1518658c}, {0x55c48851b7a3}, {0xffffffff}, {0x7fdf15186350}})
	pkg/sentry/kernel/task_syscall.go:322 +0x8e fp=0xc001d83a98 sp=0xc001d839f8 pc=0xce340e
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0xc003b1ea50?, 0x46fdec?, {{0x7fdf15186580}, {0xa}, {0x7fdf1518658c}, {0x55c48851b7a3}, {0xffffffff}, {0x7fdf15186350}})
	pkg/sentry/kernel/task_syscall.go:282 +0xc5 fp=0xc001d83b10 sp=0xc001d83a98 pc=0xce2ce5
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0xc002894a80)
	pkg/sentry/kernel/task_syscall.go:257 +0x53b fp=0xc001d83c38 sp=0xc001d83b10 pc=0xce27db
gvisor.dev/gvisor/pkg/sentry/kernel.(*runApp).execute(0xc002894a80?, 0xc002894a80)
	pkg/sentry/kernel/task_run.go:253 +0x1e2b fp=0xc001d83ec0 sp=0xc001d83c38 pc=0xccbdab
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0xc002894a80, 0xab8)
	pkg/sentry/kernel/task_run.go:94 +0x2c2 fp=0xc001d83fb0 sp=0xc001d83ec0 pc=0xcc95c2
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start.func1()
	pkg/sentry/kernel/task_start.go:378 +0x48 fp=0xc001d83fe0 sp=0xc001d83fb0 pc=0xcde988
runtime.goexit()
	src/runtime/asm_amd64.s:1571 +0x1 fp=0xc001d83fe8 sp=0xc001d83fe0 pc=0x46e1c1
created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start
	pkg/sentry/kernel/task_start.go:378 +0x1d0