panic: ptrace status unexpected: got 31, wanted stopped

DIAGNOSIS:
I0418 15:47:56.060272   12264 x:0] ***************************
I0418 15:47:56.060321   12264 x:0] Args: [/syzkaller/managers/ptrace-direct-overlay-host/current/image -root /syzkaller/managers/ptrace-direct-overlay-host/workdir/gvisor_root -watchdog-action=panic -network=none -debug -platform=ptrace -file-access=shared -network=host debug -stacks ci-gvisor-ptrace-direct-overlay-host-2]
I0418 15:47:56.060335   12264 x:0] Version release-20190304.1-122-gb52cbd602803
I0418 15:47:56.060340   12264 x:0] PID: 12264
I0418 15:47:56.060346   12264 x:0] UID: 0, GID: 0
I0418 15:47:56.060349   12264 x:0] Configuration:
I0418 15:47:56.060352   12264 x:0] 		RootDir: /syzkaller/managers/ptrace-direct-overlay-host/workdir/gvisor_root
I0418 15:47:56.060363   12264 x:0] 		Platform: ptrace
I0418 15:47:56.060377   12264 x:0] 		FileAccess: shared, overlay: false
I0418 15:47:56.060384   12264 x:0] 		Network: host, logging: false
I0418 15:47:56.060389   12264 x:0] 		Strace: false, max size: 1024, syscalls: []
I0418 15:47:56.060394   12264 x:0] ***************************
D0418 15:47:56.060418   12264 x:0] Load container "/syzkaller/managers/ptrace-direct-overlay-host/workdir/gvisor_root" "ci-gvisor-ptrace-direct-overlay-host-2"
D0418 15:47:56.062359   12264 x:0] Signal container "ci-gvisor-ptrace-direct-overlay-host-2": signal 0
D0418 15:47:56.062381   12264 x:0] Signal sandbox "ci-gvisor-ptrace-direct-overlay-host-2"
D0418 15:47:56.062386   12264 x:0] Connecting to sandbox "ci-gvisor-ptrace-direct-overlay-host-2"
D0418 15:47:56.062560   12264 x:0] urpc: successfully marshalled 118 bytes.
I0418 15:47:56.375930   12264 x:0] Found sandbox "ci-gvisor-ptrace-direct-overlay-host-2", PID: 57728
I0418 15:47:56.375952   12264 x:0] Retrieving sandbox stacks
D0418 15:47:56.375962   12264 x:0] Stacks sandbox "ci-gvisor-ptrace-direct-overlay-host-2"
D0418 15:47:56.375974   12264 x:0] Connecting to sandbox "ci-gvisor-ptrace-direct-overlay-host-2"
D0418 15:47:56.376060   12264 x:0] urpc: successfully marshalled 36 bytes.
W0418 15:47:56.424611   12264 x:0] FATAL ERROR: retrieving stacks: getting sandbox "ci-gvisor-ptrace-direct-overlay-host-2" stacks: urpc method "debug.Stacks" failed: connection reset by peer
retrieving stacks: getting sandbox "ci-gvisor-ptrace-direct-overlay-host-2" stacks: urpc method "debug.Stacks" failed: connection reset by peer