panic: munmap(600000, 200000)) failed: function not implemented

DIAGNOSIS:
I1209 02:50:00.312545   16274 x:0] ***************************
I1209 02:50:00.312602   16274 x:0] Args: [/syzkaller/managers/ptrace-direct-overlay-host-race/current/image -root /syzkaller/managers/ptrace-direct-overlay-host-race/workdir/gvisor_root -watchdog-action=panic -network=none -debug -alsologtostderr -platform=ptrace -file-access=exclusive -overlay -network=host -TESTONLY-unsafe-nonroot debug -stacks ci-gvisor-ptrace-direct-overlay-host-race-3]
I1209 02:50:00.312735   16274 x:0] Version release-20191129.0-23-g01eadf51ea54
I1209 02:50:00.312774   16274 x:0] PID: 16274
I1209 02:50:00.312807   16274 x:0] UID: 0, GID: 0
I1209 02:50:00.312831   16274 x:0] Configuration:
I1209 02:50:00.312861   16274 x:0] 		RootDir: /syzkaller/managers/ptrace-direct-overlay-host-race/workdir/gvisor_root
I1209 02:50:00.312890   16274 x:0] 		Platform: ptrace
I1209 02:50:00.312926   16274 x:0] 		FileAccess: exclusive, overlay: true
I1209 02:50:00.312974   16274 x:0] 		Network: host, logging: false
I1209 02:50:00.313035   16274 x:0] 		Strace: false, max size: 1024, syscalls: []
I1209 02:50:00.313070   16274 x:0] ***************************
W1209 02:50:00.313107   16274 x:0] Block the TERM signal. This is only safe in tests!
D1209 02:50:00.313224   16274 x:0] Load container "/syzkaller/managers/ptrace-direct-overlay-host-race/workdir/gvisor_root" "ci-gvisor-ptrace-direct-overlay-host-race-3"
D1209 02:50:00.342725   16274 x:0] Signal container "ci-gvisor-ptrace-direct-overlay-host-race-3": signal 0
D1209 02:50:00.343099   16274 x:0] Signal sandbox "ci-gvisor-ptrace-direct-overlay-host-race-3"
D1209 02:50:00.343514   16274 x:0] Connecting to sandbox "ci-gvisor-ptrace-direct-overlay-host-race-3"
D1209 02:50:00.343981   16274 x:0] urpc: successfully marshalled 123 bytes.
I1209 02:50:00.681193   16274 x:0] Found sandbox "ci-gvisor-ptrace-direct-overlay-host-race-3", PID: 23047
I1209 02:50:00.681309   16274 x:0] Retrieving sandbox stacks
D1209 02:50:00.681346   16274 x:0] Stacks sandbox "ci-gvisor-ptrace-direct-overlay-host-race-3"
D1209 02:50:00.681406   16274 x:0] Connecting to sandbox "ci-gvisor-ptrace-direct-overlay-host-race-3"
D1209 02:50:00.681606   16274 x:0] urpc: successfully marshalled 36 bytes.
W1209 02:50:00.743830   16274 x:0] FATAL ERROR: retrieving stacks: getting sandbox "ci-gvisor-ptrace-direct-overlay-host-race-3" stacks: urpc method "debug.Stacks" failed: connection reset by peer
retrieving stacks: getting sandbox "ci-gvisor-ptrace-direct-overlay-host-race-3" stacks: urpc method "debug.Stacks" failed: connection reset by peer
W1209 02:50:00.744157   16274 x:0] Failure to execute command, err: 1