panic: munmap(7fbf1d800000, 200000)) failed: function not implemented

DIAGNOSIS:
I0102 22:00:43.409149   60831 x:0] ***************************
I0102 22:00:43.409166   60831 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 -alsologtostderr -platform=ptrace -file-access=shared -network=host debug -stacks --ps ci-gvisor-ptrace-direct-overlay-host-1]
I0102 22:00:43.409372   60831 x:0] Version release-20191213.0-56-g1f384ac42b9e
I0102 22:00:43.409386   60831 x:0] PID: 60831
I0102 22:00:43.409394   60831 x:0] UID: 0, GID: 0
I0102 22:00:43.409398   60831 x:0] Configuration:
I0102 22:00:43.409401   60831 x:0] 		RootDir: /syzkaller/managers/ptrace-direct-overlay-host/workdir/gvisor_root
I0102 22:00:43.409405   60831 x:0] 		Platform: ptrace
I0102 22:00:43.409409   60831 x:0] 		FileAccess: shared, overlay: false
I0102 22:00:43.409480   60831 x:0] 		Network: host, logging: false
I0102 22:00:43.409494   60831 x:0] 		Strace: false, max size: 1024, syscalls: []
I0102 22:00:43.409499   60831 x:0] ***************************
D0102 22:00:43.409566   60831 x:0] Load container "/syzkaller/managers/ptrace-direct-overlay-host/workdir/gvisor_root" "ci-gvisor-ptrace-direct-overlay-host-1"
D0102 22:00:43.412448   60831 x:0] Signal container "ci-gvisor-ptrace-direct-overlay-host-1": signal 0
D0102 22:00:43.412472   60831 x:0] Signal sandbox "ci-gvisor-ptrace-direct-overlay-host-1"
D0102 22:00:43.412478   60831 x:0] Connecting to sandbox "ci-gvisor-ptrace-direct-overlay-host-1"
D0102 22:00:43.412743   60831 x:0] urpc: successfully marshalled 118 bytes.
I0102 22:00:43.897630   60831 x:0] Found sandbox "ci-gvisor-ptrace-direct-overlay-host-1", PID: 8558
I0102 22:00:43.897669   60831 x:0] Retrieving sandbox stacks
D0102 22:00:43.897677   60831 x:0] Stacks sandbox "ci-gvisor-ptrace-direct-overlay-host-1"
D0102 22:00:43.897684   60831 x:0] Connecting to sandbox "ci-gvisor-ptrace-direct-overlay-host-1"
D0102 22:00:43.897762   60831 x:0] urpc: successfully marshalled 36 bytes.
W0102 22:00:43.937802   60831 x:0] FATAL ERROR: retrieving stacks: getting sandbox "ci-gvisor-ptrace-direct-overlay-host-1" stacks: urpc method "debug.Stacks" failed: connection reset by peer
retrieving stacks: getting sandbox "ci-gvisor-ptrace-direct-overlay-host-1" stacks: urpc method "debug.Stacks" failed: connection reset by peer
W0102 22:00:43.937895   60831 x:0] Failure to execute command, err: 1