panic: Incrementing non-positive ref count

goroutine 275901 [running]:
gvisor.googlesource.com/gvisor/pkg/refs.(*AtomicRefCount).IncRef(0xc420dce320)
	pkg/refs/refcounter.go:211 +0x5a
gvisor.googlesource.com/gvisor/pkg/sentry/fs.(*Dirent).IncRef(0xc420dce320)
	pkg/sentry/fs/dirent.go:1302 +0x46
gvisor.googlesource.com/gvisor/pkg/sentry/fs.(*MountSource).Root(0xc4214f5950, 0x0)
	pkg/sentry/fs/mount.go:206 +0x7b
gvisor.googlesource.com/gvisor/pkg/sentry/fs/proc.forEachMountSource(0xc420f7f200, 0xc4207e34e0)
	pkg/sentry/fs/proc/mounts.go:61 +0x20c
gvisor.googlesource.com/gvisor/pkg/sentry/fs/proc.(*mountInfoFile).ReadSeqFileData(0xc4210e8120, 0xc7a800, 0xc421a5fb00, 0x0, 0x0, 0x683ff6, 0xc420212120, 0xd6, 0x10f)
	pkg/sentry/fs/proc/mounts.go:90 +0x75
gvisor.googlesource.com/gvisor/pkg/sentry/fs/proc/seqfile.(*SeqFile).updateSourceLocked(0xc421672640, 0xc7a800, 0xc421a5fb00, 0x0)
	pkg/sentry/fs/proc/seqfile/seqfile.go:225 +0x97
gvisor.googlesource.com/gvisor/pkg/sentry/fs/proc/seqfile.(*SeqFile).DeprecatedPreadv(0xc421672640, 0xc7a800, 0xc421a5fb00, 0xc79540, 0xc4208cd900, 0x0, 0x1, 0x20000100, 0x0, 0x100, ...)
	pkg/sentry/fs/proc/seqfile/seqfile.go:190 +0x707
gvisor.googlesource.com/gvisor/pkg/sentry/fs/fsutil.(*Handle).Read(0xc4204e73e0, 0xc7a800, 0xc421a5fb00, 0xc4214f5830, 0xc79540, 0xc4208cd900, 0x0, 0x1, 0x20000100, 0x0, ...)
	pkg/sentry/fs/fsutil/handle.go:90 +0x8e
gvisor.googlesource.com/gvisor/pkg/sentry/fs.(*File).Readv(0xc4214f5830, 0xc7a800, 0xc421a5fb00, 0xc79540, 0xc4208cd900, 0x0, 0x1, 0x20000100, 0x0, 0x100, ...)
	pkg/sentry/fs/file.go:230 +0x116
gvisor.googlesource.com/gvisor/pkg/sentry/syscalls/linux.readv(0xc421a5fb00, 0xc4214f5830, 0xc79540, 0xc4208cd900, 0x0, 0x1, 0x20000100, 0x0, 0x100, 0x0, ...)
	pkg/sentry/syscalls/linux/sys_read.go:191 +0x91
gvisor.googlesource.com/gvisor/pkg/sentry/syscalls/linux.Read(0xc421a5fb00, 0x3, 0x20000100, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
	pkg/sentry/syscalls/linux/sys_read.go:67 +0x21e
gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0xc421a5fb00, 0x0, 0x3, 0x20000100, 0x0, 0x0, 0x0, 0x0, 0xc42000a220, 0xbb9fc0, ...)
	pkg/sentry/kernel/task_syscall.go:162 +0x307
gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0xc421a5fb00, 0x0, 0x3, 0x20000100, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0)
	pkg/sentry/kernel/task_syscall.go:278 +0x62
gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0xc421a5fb00, 0x0, 0x3, 0x20000100, 0x0, 0x0, 0x0, 0x0, 0xc6d8e0, 0xc42088fe00)
	pkg/sentry/kernel/task_syscall.go:241 +0x91
gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0xc421a5fb00, 0x2, 0xc4202165a0)
	pkg/sentry/kernel/task_syscall.go:216 +0x10c
gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*runApp).execute(0x0, 0xc421a5fb00, 0xc6d8e0, 0x0)
	pkg/sentry/kernel/task_run.go:217 +0xed8
gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).run(0xc421a5fb00, 0x23f0)
	pkg/sentry/kernel/task_run.go:95 +0x174
created by gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).Start
	pkg/sentry/kernel/task_start.go:251 +0x100