panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x9604f3]

goroutine 163 [running]:
panic({0x10f0e60, 0x1e47d50})
	GOROOT/src/runtime/panic.go:1147 +0x3a8 fp=0xc0008cd490 sp=0xc0008cd3d0 pc=0x4351c8
runtime.panicmem(...)
	GOROOT/src/runtime/panic.go:221
runtime.sigpanic()
	GOROOT/src/runtime/signal_unix.go:735 +0x327 fp=0xc0008cd4e0 sp=0xc0008cd490 pc=0x44bd67
gvisor.dev/gvisor/pkg/sentry/kernel.(*ThreadGroup).MigrateCgroup(0x14383c8, {0xc0002a6ea0, {0x142e620, 0xc0007eca80}})
	pkg/sentry/kernel/task_cgroup.go:140 +0x73 fp=0xc0008cd5b8 sp=0xc0008cd4e0 pc=0x9604f3
gvisor.dev/gvisor/pkg/sentry/fsimpl/cgroupfs.(*cgroupProcsData).Write(0xc0009b0008, {0x1444e70, 0xc000540000}, 0xc0002f43e0, {{0x14383c8, 0xc000129000}, {0x0, 0x1, 0x20000080, 0xb}, ...}, ...)
	pkg/sentry/fsimpl/cgroupfs/base.go:305 +0x109 fp=0xc0008cd620 sp=0xc0008cd5b8 pc=0xbd3849
gvisor.dev/gvisor/pkg/sentry/vfs.(*DynamicBytesFileDescriptionImpl).pwriteLocked(0xc0002f4380, {0x1444e70, 0xc000540000}, {{0x14383c8, 0xc000129000}, {0x0, 0x1, 0x20000080, 0xb}, {0x0, ...}}, ...)
	pkg/sentry/vfs/file_description_impl_util.go:381 +0x26a fp=0xc0008cd740 sp=0xc0008cd620 pc=0x6fca2a
gvisor.dev/gvisor/pkg/sentry/vfs.(*DynamicBytesFileDescriptionImpl).Write(0xc0002f4380, {0x1444e70, 0xc000540000}, {{0x14383c8, 0xc000129000}, {0x0, 0x1, 0x20000080, 0xb}, {0x0, ...}}, ...)
	pkg/sentry/vfs/file_description_impl_util.go:402 +0xb0 fp=0xc0008cd7d8 sp=0xc0008cd740 pc=0x6fcd10
gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs.(*DynamicBytesFD).Write(0xc0002f43e0, {0x1444e70, 0xc000540000}, {{0x14383c8, 0xc000129000}, {0x0, 0x1, 0x20000080, 0xb}, {0x0, ...}}, ...)
	pkg/sentry/fsimpl/kernfs/dynamic_bytes_file.go:125 +0x58 fp=0xc0008cd840 sp=0xc0008cd7d8 pc=0x7e6118
gvisor.dev/gvisor/pkg/sentry/vfs.(*FileDescription).Write(0xc0002f43e0, {0x1444e70, 0xc000540000}, {{0x14383c8, 0xc000129000}, {0x0, 0x1, 0x20000080, 0xb}, {0x0, ...}}, ...)
	pkg/sentry/vfs/file_description.go:665 +0x91 fp=0xc0008cd8c0 sp=0xc0008cd840 pc=0x6f9a11
gvisor.dev/gvisor/pkg/sentry/syscalls/linux/vfs2.write(0xc000540000, 0xc0002f43e0, {{0x14383c8, 0xc000129000}, {0x0, 0x1, 0x20000080, 0xb}, {0x0, 0x1}}, ...)
	pkg/sentry/syscalls/linux/vfs2/read_write.go:348 +0x85 fp=0xc0008cda10 sp=0xc0008cd8c0 pc=0xe0fb65
gvisor.dev/gvisor/pkg/sentry/syscalls/linux/vfs2.Write(0xc000540000, {{0x4}, {0x20000080}, {0xb}, {0x0}, {0x17}, {0x0}})
	pkg/sentry/syscalls/linux/vfs2/read_write.go:317 +0x210 fp=0xc0008cdb50 sp=0xc0008cda10 pc=0xe0f3f0
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).executeSyscall(0xc000540000, 0x1, {{0x4}, {0x20000080}, {0xb}, {0x0}, {0x17}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:103 +0x376 fp=0xc0008cdca0 sp=0xc0008cdb50 pc=0x97c076
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke(0xc000540000, 0xc00044135c, {{0x4}, {0x20000080}, {0xb}, {0x0}, {0x17}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:238 +0x4d fp=0xc0008cdd10 sp=0xc0008cdca0 pc=0x97cbed
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter(0xc00012a168, 0x540000, {{0x4}, {0x20000080}, {0xb}, {0x0}, {0x17}, {0x0}})
	pkg/sentry/kernel/task_syscall.go:198 +0x65 fp=0xc0008cdd70 sp=0xc0008cdd10 pc=0x97c8a5
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).doSyscall(0xc000540000)
	pkg/sentry/kernel/task_syscall.go:173 +0x31a fp=0xc0008cde38 sp=0xc0008cdd70 pc=0x97c5da
gvisor.dev/gvisor/pkg/sentry/kernel.(*runApp).execute(0xc0008a4080, 0xc000540000)
	pkg/sentry/kernel/task_run.go:254 +0xe45 fp=0xc0008cdf60 sp=0xc0008cde38 pc=0x9714e5
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).run(0xc000540000, 0x13)
	pkg/sentry/kernel/task_run.go:95 +0x1ac fp=0xc0008cdfc0 sp=0xc0008cdf60 pc=0x97002c
gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start·dwrap·236()
	pkg/sentry/kernel/task_start.go:339 +0x2a fp=0xc0008cdfe0 sp=0xc0008cdfc0 pc=0x97abca
runtime.goexit()
	src/runtime/asm_amd64.s:1581 +0x1 fp=0xc0008cdfe8 sp=0xc0008cdfe0 pc=0x469321
created by gvisor.dev/gvisor/pkg/sentry/kernel.(*Task).Start
	pkg/sentry/kernel/task_start.go:339 +0xfe