panic: ptrace status unexpected: got 31, wanted stopped

goroutine 4256975 [running]:
gvisor.googlesource.com/gvisor/pkg/sentry/platform/ptrace.(*thread).wait(0xc001270ff0, 0x0, 0x3d3c)
	pkg/sentry/platform/ptrace/subprocess.go:323 +0x4b9
DIAGNOSIS:
I0427 03:20:12.670184   42239 x:0] ***************************
I0427 03:20:12.670309   42239 x:0] Args: [/syzkaller/managers/kvm-direct-overlay-host-race/current/image -root /syzkaller/managers/kvm-direct-overlay-host-race/workdir/gvisor_root -watchdog-action=panic -network=none -debug -platform=ptrace -file-access=exclusive -overlay -network=host debug -stacks ci-gvisor-kvm-direct-overlay-host-race-2]
I0427 03:20:12.670388   42239 x:0] Version release-20190304.1-149-g5f13338d30fb
I0427 03:20:12.670406   42239 x:0] PID: 42239
I0427 03:20:12.670439   42239 x:0] UID: 0, GID: 0
I0427 03:20:12.670478   42239 x:0] Configuration:
I0427 03:20:12.670492   42239 x:0] 		RootDir: /syzkaller/managers/kvm-direct-overlay-host-race/workdir/gvisor_root
I0427 03:20:12.670530   42239 x:0] 		Platform: ptrace
I0427 03:20:12.670585   42239 x:0] 		FileAccess: exclusive, overlay: true
I0427 03:20:12.670619   42239 x:0] 		Network: host, logging: false
I0427 03:20:12.670639   42239 x:0] 		Strace: false, max size: 1024, syscalls: []
I0427 03:20:12.670663   42239 x:0] ***************************
D0427 03:20:12.670906   42239 x:0] Load container "/syzkaller/managers/kvm-direct-overlay-host-race/workdir/gvisor_root" "ci-gvisor-kvm-direct-overlay-host-race-2"
D0427 03:20:12.678133   42239 x:0] Signal container "ci-gvisor-kvm-direct-overlay-host-race-2": signal 0
D0427 03:20:12.678197   42239 x:0] Signal sandbox "ci-gvisor-kvm-direct-overlay-host-race-2"
D0427 03:20:12.678239   42239 x:0] Connecting to sandbox "ci-gvisor-kvm-direct-overlay-host-race-2"
D0427 03:20:12.678666   42239 x:0] urpc: successfully marshalled 120 bytes.
I0427 03:20:13.374079   42239 x:0] Found sandbox "ci-gvisor-kvm-direct-overlay-host-race-2", PID: 63344
I0427 03:20:13.374145   42239 x:0] Retrieving sandbox stacks
D0427 03:20:13.374164   42239 x:0] Stacks sandbox "ci-gvisor-kvm-direct-overlay-host-race-2"
D0427 03:20:13.374203   42239 x:0] Connecting to sandbox "ci-gvisor-kvm-direct-overlay-host-race-2"
W0427 03:20:13.374307   42239 x:0] FATAL ERROR: retrieving stacks: connecting to control server at PID 63344: connection refused
retrieving stacks: connecting to control server at PID 63344: connection refused