panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x9e14a5]

goroutine 325 [running]:
panic({0x11f0ea0, 0x2119f30})
	GOROOT/src/runtime/panic.go:1147 +0x3a8 fp=0xc000b43540 sp=0xc000b43480 pc=0x4351c8
runtime.panicmem(...)
	GOROOT/src/runtime/panic.go:221
runtime.sigpanic()
	GOROOT/src/runtime/signal_unix.go:735 +0x327 fp=0xc000b43590 sp=0xc000b43540 pc=0x44bd67
gvisor.dev/gvisor/pkg/sentry/kernel.(*ThreadGroup).MigrateCgroup(0x0, {0xc0008d0240, {0x155fbe0, 0xc0008cfc00}})
	pkg/sentry/kernel/task_cgroup.go:140 +0x85 fp=0xc000b43668 sp=0xc000b43590 pc=0x9e14a5
gvisor.dev/gvisor/pkg/sentry/fsimpl/cgroupfs.(*cgroupProcsData).Write(0xc0004f8030, {0x1576490, 0xc000b2ea80}, 0xc0007903e0, {{0x15698c8, 0xc000725000}, {0x0, 0x1, 0x20000080, 0xb}, ...}, ...)
	pkg/sentry/fsimpl/cgroupfs/base.go:305 +0x131 fp=0xc000b436d0 sp=0xc000b43668 pc=0xc9db91
gvisor.dev/gvisor/pkg/sentry/vfs.(*DynamicBytesFileDescriptionImpl).pwriteLocked(0xc000790380, {0x1576490, 0xc000b2ea80}, {{0x15698c8, 0xc000725000}, {0x0, 0x1, 0x20000080, 0xb}, {0x0, ...}}, ...)
	pkg/sentry/vfs/file_description_impl_util.go:381 +0x2a3 fp=0xc000b437f0 sp=0xc000b436d0 pc=0x7298c3
gvisor.dev/gvisor/pkg/sentry/vfs.(*DynamicBytesFileDescriptionImpl).Write(0xc000790380, {0x1576490, 0xc000b2ea80}, {{0x15698c8, 0xc000725000}, {0x0, 0x1, 0x20000080, 0xb}, {0x0, ...}}, ...)
	pkg/sentry/vfs/file_description_impl_util.go:402 +0xb2 fp=0xc000b43880 sp=0xc000b437f0 pc=0x729bf2
gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs.(*DynamicBytesFD).Write(0xc000b43978, {0x1576490, 0xc000b2ea80}, {{0x15698c8, 0xc000725000}, {0x0, 0x1, 0x20000080, 0xb}, {0x0, ...}}, ...)
	pkg/sentry/fsimpl/kernfs/dynamic_bytes_file.go:125 +0x65 fp=0xc000b438e8 sp=0xc000b43880 pc=0x8350c5
gvisor.dev/gvisor/pkg/sentry/vfs.(*FileDescription).Write(0xc0007903e0, {0x1576490, 0xc000b2ea80}, {{0x15698c8, 0xc000725000}, {0x0, 0x1, 0x20000080, 0xb}, {0x0, ...}}, ...)
	pkg/sentry/vfs/file_description.go:665 +0xa5 fp=0xc000b43968 sp=0xc000b438e8 pc=0x726465
gvisor.dev/gvisor/pkg/sentry/syscalls/linux/vfs2.write(0x43fcb1, 0xc0007903e0, {{0x15698c8, 0xc000725000}, {0x0, 0x1, 0x20000080, 0xb}, {0x0, 0x1}}, ...)
	pkg/sentry/syscalls/linux/vfs2/read_write.go:348 +0x8e fp=0xc000b43ab8 sp=0xc000b43968 pc=0xef958e
gvisor.dev/gvisor/pkg/sentry/syscalls/linux/vfs2.Write(0xc000b2ea80, {{0x4}, {0x20000080}, {0xb}, {0x0}, {0x17}, {0x0}})
	pkg/sentry/syscalls/linux/vfs2/read_write.go:317 +0x265 fp=0xc000b43bf8 sp=0xc000b43ab8 pc=0xef8d65
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0xc000b2ea80, 0x1, {{0x4}, {0x20000080}, {0xb}, {0x0}, {0x17}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:103 +0x2d7 fp=0xc000b43ca8 sp=0xc000b43bf8 pc=0xa020f7
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0xc000b2ea80, 0xf591a0, {{0x4}, {0x20000080}, {0xb}, {0x0}, {0x17}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:238 +0x57 fp=0xc000b43d18 sp=0xc000b43ca8 pc=0xa02eb7
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0xc000b6e340, 0x158a4b8, {{0x4}, {0x20000080}, {0xb}, {0x0}, {0x17}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:198 +0x85 fp=0xc000b43d78 sp=0xc000b43d18 pc=0xa02a85
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0xc000b2ea80)
	pkg/sentry/kernel/task_syscall.go:173 +0x38e fp=0xc000b43e40 sp=0xc000b43d78 pc=0xa0274e
gvisor.dev/gvisor/pkg/sentry/kernel.(*runApp).execute(0xc0006ac100, 0xc000b2ea80)
	pkg/sentry/kernel/task_run.go:254 +0x111b fp=0xc000b43f60 sp=0xc000b43e40 pc=0x9f583b
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0xc000b2ea80, 0x11)
	pkg/sentry/kernel/task_run.go:95 +0x1ec fp=0xc000b43fc0 sp=0xc000b43f60 pc=0x9f40ac
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start·dwrap·236()
	pkg/sentry/kernel/task_start.go:339 +0x2a fp=0xc000b43fe0 sp=0xc000b43fc0 pc=0xa00a6a
runtime.goexit()
	src/runtime/asm_amd64.s:1581 +0x1 fp=0xc000b43fe8 sp=0xc000b43fe0 pc=0x469321
created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start
	pkg/sentry/kernel/task_start.go:339 +0x106