panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0xc9e39f]

goroutine 280 [running]:
panic({0x184c720, 0x2795c50})
	GOROOT/src/runtime/panic.go:1147 +0x3a8 fp=0xc00025cf48 sp=0xc00025ce88 pc=0x437d08
runtime.panicmem(...)
	GOROOT/src/runtime/panic.go:221
runtime.sigpanic()
	GOROOT/src/runtime/signal_unix.go:735 +0x327 fp=0xc00025cf98 sp=0xc00025cf48 pc=0x450187
gvisor.dev/gvisor/pkg/sentry/kernel.(*ThreadGroup).MigrateCgroup(0x0, {0xc000314b40, {0x1ccdc00, 0xc000364e00}})
	pkg/sentry/kernel/task_cgroup.go:140 +0x7f fp=0xc00025d0c0 sp=0xc00025cf98 pc=0xc9e39f
gvisor.dev/gvisor/pkg/sentry/fsimpl/cgroupfs.(*cgroupProcsData).Write(0xc00052a008, {0x1ce4550, 0xc0005bf500}, 0xc00002e300, {{0x1cd7528, 0xc000880000}, {0x0, 0x1, 0x20000080, 0xb}, ...}, ...)
	pkg/sentry/fsimpl/cgroupfs/base.go:305 +0x1c5 fp=0xc00025d170 sp=0xc00025d0c0 pc=0x1040445
gvisor.dev/gvisor/pkg/sentry/vfs.(*DynamicBytesFileDescriptionImpl).pwriteLocked(0xc00002e2a0, {0x1ce4550, 0xc0005bf500}, {{0x1cd7528, 0xc000880000}, {0x0, 0x1, 0x20000080, 0xb}, {0x0, ...}}, ...)
	pkg/sentry/vfs/file_description_impl_util.go:381 +0x2c4 fp=0xc00025d2d0 sp=0xc00025d170 pc=0x8dd204
gvisor.dev/gvisor/pkg/sentry/vfs.(*DynamicBytesFileDescriptionImpl).Write(0xc00002e2a0, {0x1ce4550, 0xc0005bf500}, {{0x1cd7528, 0xc000880000}, {0x0, 0x1, 0x20000080, 0xb}, {0x0, ...}}, ...)
	pkg/sentry/vfs/file_description_impl_util.go:402 +0x11d fp=0xc00025d3b0 sp=0xc00025d2d0 pc=0x8dd63d
gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs.(*DynamicBytesFD).Write(0xc00002e2a0, {0x1ce4550, 0xc0005bf500}, {{0x1cd7528, 0xc000880000}, {0x0, 0x1, 0x20000080, 0xb}, {0x0, ...}}, ...)
	pkg/sentry/fsimpl/kernfs/dynamic_bytes_file.go:125 +0x9b fp=0xc00025d438 sp=0xc00025d3b0 pc=0xa5741b
gvisor.dev/gvisor/pkg/sentry/vfs.(*FileDescription).Write(0xc00002e300, {0x1ce4550, 0xc0005bf500}, {{0x1cd7528, 0xc000880000}, {0x0, 0x1, 0x20000080, 0xb}, {0x0, ...}}, ...)
	pkg/sentry/vfs/file_description.go:665 +0x125 fp=0xc00025d508 sp=0xc00025d438 pc=0x8d85e5
gvisor.dev/gvisor/pkg/sentry/syscalls/linux/vfs2.write(0xc00002e300, 0xc00002e300, {{0x1cd7528, 0xc000880000}, {0x0, 0x1, 0x20000080, 0xb}, {0x0, 0x1}}, ...)
	pkg/sentry/syscalls/linux/vfs2/read_write.go:348 +0x9d fp=0xc00025d690 sp=0xc00025d508 pc=0x1376cdd
gvisor.dev/gvisor/pkg/sentry/syscalls/linux/vfs2.Write(0xc0005bf500, {{0x4}, {0x20000080}, {0xb}, {0x0}, {0x17}, {0x0}})
	pkg/sentry/syscalls/linux/vfs2/read_write.go:317 +0x2c5 fp=0xc00025d830 sp=0xc00025d690 pc=0x1376365
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0xc0005bf500, 0x1, {{0x4}, {0x20000080}, {0xb}, {0x0}, {0x17}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:103 +0x4dc fp=0xc00025da80 sp=0xc00025d830 pc=0xccef9c
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0xc0005bf500, 0x46f7f9, {{0x4}, {0x20000080}, {0xb}, {0x0}, {0x17}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:238 +0x6a fp=0xc00025db08 sp=0xc00025da80 pc=0xcd004a
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0xc0005bc1e0, 0x46fcac, {{0x4}, {0x20000080}, {0xb}, {0x0}, {0x17}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:198 +0x8f fp=0xc00025db80 sp=0xc00025db08 pc=0xccfacf
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0xc0005bf500)
	pkg/sentry/kernel/task_syscall.go:173 +0x3c5 fp=0xc00025dc88 sp=0xc00025db80 pc=0xccf705
gvisor.dev/gvisor/pkg/sentry/kernel.(*runApp).execute(0xc0005bf500, 0xc0005bf500)
	pkg/sentry/kernel/task_run.go:254 +0x1698 fp=0xc00025deb8 sp=0xc00025dc88 pc=0xcbc058
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0xc0005bf500, 0xd)
	pkg/sentry/kernel/task_run.go:95 +0x35b fp=0xc00025dfb0 sp=0xc00025deb8 pc=0xcb9f9b
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start·dwrap·236()
	pkg/sentry/kernel/task_start.go:339 +0x48 fp=0xc00025dfe0 sp=0xc00025dfb0 pc=0xcccfa8
runtime.goexit()
	src/runtime/asm_amd64.s:1581 +0x1 fp=0xc00025dfe8 sp=0xc00025dfe0 pc=0x46e081
created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start
	pkg/sentry/kernel/task_start.go:339 +0x1a9