panic: Decrementing non-positive ref count 0xc0007721a0, owned by vfs.Filesystem

goroutine 290 [running]:
panic({0x10f2ce0?, 0xc000196450?})
	GOROOT/src/runtime/panic.go:1017 +0x3ac fp=0xc000ae3388 sp=0xc000ae32d8 pc=0x43a72c
gvisor.dev/gvisor/pkg/sentry/vfs.(*FilesystemRefs).DecRef(0xc0007721a0, 0xc000960d90?)
	bazel-out/k8-fastbuild/bin/pkg/sentry/vfs/filesystem_refs.go:126 +0x154 fp=0xc000ae33f0 sp=0xc000ae3388 pc=0x791474
gvisor.dev/gvisor/pkg/sentry/vfs.(*Filesystem).DecRef(0xc000ae3470?, {0x1580618?, 0xc000ada000?})
	pkg/sentry/vfs/filesystem.go:77 +0x55 fp=0xc000ae3430 sp=0xc000ae33f0 pc=0x790a55
gvisor.dev/gvisor/pkg/sentry/vfs.(*VirtualFilesystem).unlockMounts(0xc0002776d8, {0x1580618, 0xc000ada000})
	pkg/sentry/vfs/vfs.go:1030 +0x1df fp=0xc000ae34e0 sp=0xc000ae3430 pc=0x7afedf
gvisor.dev/gvisor/pkg/sentry/vfs.(*Mount).destroy.func1()
	pkg/sentry/vfs/mount.go:826 +0x28 fp=0xc000ae3508 sp=0xc000ae34e0 pc=0x79a8e8
gvisor.dev/gvisor/pkg/sentry/vfs.(*Mount).destroy(0xc00053e4d0, {0x1580618, 0xc000ada000})
	pkg/sentry/vfs/mount.go:839 +0x282 fp=0xc000ae35a8 sp=0xc000ae3508 pc=0x79a842
gvisor.dev/gvisor/pkg/sentry/vfs.(*Mount).DecRef(0xc00053e4d0, {0x1580618, 0xc000ada000})
	pkg/sentry/vfs/mount.go:820 +0xa5 fp=0xc000ae35d0 sp=0xc000ae35a8 pc=0x79a585
gvisor.dev/gvisor/pkg/sentry/vfs.(*VirtualFilesystem).unlockMounts(0xc0002776d8, {0x1580618, 0xc000ada000})
	pkg/sentry/vfs/vfs.go:1030 +0x1df fp=0xc000ae3680 sp=0xc000ae35d0 pc=0x7afedf
gvisor.dev/gvisor/pkg/sentry/vfs.(*VirtualFilesystem).UmountAt.func2()
	pkg/sentry/vfs/mount.go:578 +0x28 fp=0xc000ae36a8 sp=0xc000ae3680 pc=0x7997a8
gvisor.dev/gvisor/pkg/sentry/vfs.(*VirtualFilesystem).UmountAt(0xc0002776d8, {0x1580618, 0xc000ada000}, 0xc000ae9400?, 0xc000a88e00?, 0xc000ae3804)
	pkg/sentry/vfs/mount.go:602 +0x342 fp=0xc000ae3778 sp=0xc000ae36a8 pc=0x799582
gvisor.dev/gvisor/pkg/sentry/syscalls/linux.Umount2(0xc000ada000, 0x0?, {{0x7fbddb35fa90}, {0xa}, {0x0}, {0xffffffff}, {0x0}, {0x0}})
	pkg/sentry/syscalls/linux/sys_mount.go:164 +0x2f7 fp=0xc000ae3910 sp=0xc000ae3778 pc=0xb94957
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0xc000ada000, 0xa6, {{0x7fbddb35fa90}, {0xa}, {0x0}, {0xffffffff}, {0x0}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:142 +0x80b fp=0xc000ae3c50 sp=0xc000ae3910 pc=0xa2298b
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0xc000ada000, 0xc000ac42d0?, {{0x7fbddb35fa90}, {0xa}, {0x0}, {0xffffffff}, {0x0}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:322 +0x4e fp=0xc000ae3cb0 sp=0xc000ae3c50 pc=0xa23f8e
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0x0?, 0xc000ab2878?, {{0x7fbddb35fa90}, {0xa}, {0x0}, {0xffffffff}, {0x0}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:282 +0x74 fp=0xc000ae3d10 sp=0xc000ae3cb0 pc=0xa23b54
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0xc000a9a4e0?)
	pkg/sentry/kernel/task_syscall.go:257 +0x3a8 fp=0xc000ae3e08 sp=0xc000ae3d10 pc=0xa23848
gvisor.dev/gvisor/pkg/sentry/kernel.(*runApp).execute(0xc0006d1700?, 0xc000ada000)
	pkg/sentry/kernel/task_run.go:269 +0x1405 fp=0xc000ae3f48 sp=0xc000ae3e08 pc=0xa15945
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0xc000ada000, 0x7)
	pkg/sentry/kernel/task_run.go:98 +0x262 fp=0xc000ae3fc0 sp=0xc000ae3f48 pc=0xa13e62
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start.func1()
	pkg/sentry/kernel/task_start.go:391 +0x25 fp=0xc000ae3fe0 sp=0xc000ae3fc0 pc=0xa20e85
runtime.goexit()
	src/runtime/asm_amd64.s:1650 +0x1 fp=0xc000ae3fe8 sp=0xc000ae3fe0 pc=0x471241
created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start in goroutine 275
	pkg/sentry/kernel/task_start.go:391 +0xf8