panic: ptrace status unexpected: got 31, wanted stopped

DIAGNOSIS:
I0529 18:34:37.369598   14888 x:0] ***************************
I0529 18:34:37.369732   14888 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]
I0529 18:34:37.369804   14888 x:0] Version release-20190304.1-233-ged5793808e9d
I0529 18:34:37.369841   14888 x:0] PID: 14888
I0529 18:34:37.369870   14888 x:0] UID: 0, GID: 0
I0529 18:34:37.369897   14888 x:0] Configuration:
I0529 18:34:37.369912   14888 x:0] 		RootDir: /syzkaller/managers/kvm-direct-overlay-host-race/workdir/gvisor_root
I0529 18:34:37.369958   14888 x:0] 		Platform: ptrace
I0529 18:34:37.370011   14888 x:0] 		FileAccess: exclusive, overlay: true
I0529 18:34:37.370035   14888 x:0] 		Network: host, logging: false
I0529 18:34:37.370063   14888 x:0] 		Strace: false, max size: 1024, syscalls: []
I0529 18:34:37.370090   14888 x:0] ***************************
D0529 18:34:37.370475   14888 x:0] Load container "/syzkaller/managers/kvm-direct-overlay-host-race/workdir/gvisor_root" "ci-gvisor-kvm-direct-overlay-host-race-2"
D0529 18:34:37.381339   14888 x:0] Signal container "ci-gvisor-kvm-direct-overlay-host-race-2": signal 0
D0529 18:34:37.381630   14888 x:0] Signal sandbox "ci-gvisor-kvm-direct-overlay-host-race-2"
D0529 18:34:37.381681   14888 x:0] Connecting to sandbox "ci-gvisor-kvm-direct-overlay-host-race-2"
D0529 18:34:37.398418   14888 x:0] urpc: successfully marshalled 120 bytes.
I0529 18:34:37.766720   14888 x:0] Found sandbox "ci-gvisor-kvm-direct-overlay-host-race-2", PID: 62423
I0529 18:34:37.766798   14888 x:0] Retrieving sandbox stacks
D0529 18:34:37.766821   14888 x:0] Stacks sandbox "ci-gvisor-kvm-direct-overlay-host-race-2"
D0529 18:34:37.766857   14888 x:0] Connecting to sandbox "ci-gvisor-kvm-direct-overlay-host-race-2"
D0529 18:34:37.767000   14888 x:0] urpc: successfully marshalled 36 bytes.
W0529 18:34:37.848677   14888 x:0] FATAL ERROR: retrieving stacks: getting sandbox "ci-gvisor-kvm-direct-overlay-host-race-2" stacks: urpc method "debug.Stacks" failed: connection reset by peer
retrieving stacks: getting sandbox "ci-gvisor-kvm-direct-overlay-host-race-2" stacks: urpc method "debug.Stacks" failed: connection reset by peer