panic: munmap(6e7000, 49000)) failed: function not implemented

DIAGNOSIS:
I1219 09:01:17.964465   59112 x:0] ***************************
I1219 09:01:17.964544   59112 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 --ps ci-gvisor-ptrace-direct-overlay-host-race-1]
I1219 09:01:17.964750   59112 x:0] Version release-20191210.0-52-g628948b1e197
I1219 09:01:17.964794   59112 x:0] PID: 59112
I1219 09:01:17.964847   59112 x:0] UID: 0, GID: 0
I1219 09:01:17.964878   59112 x:0] Configuration:
I1219 09:01:17.964943   59112 x:0] 		RootDir: /syzkaller/managers/ptrace-direct-overlay-host-race/workdir/gvisor_root
I1219 09:01:17.964988   59112 x:0] 		Platform: ptrace
I1219 09:01:17.965158   59112 x:0] 		FileAccess: exclusive, overlay: true
I1219 09:01:17.965721   59112 x:0] 		Network: host, logging: false
I1219 09:01:17.965768   59112 x:0] 		Strace: false, max size: 1024, syscalls: []
I1219 09:01:17.965836   59112 x:0] ***************************
W1219 09:01:17.965882   59112 x:0] Block the TERM signal. This is only safe in tests!
D1219 09:01:17.966043   59112 x:0] Load container "/syzkaller/managers/ptrace-direct-overlay-host-race/workdir/gvisor_root" "ci-gvisor-ptrace-direct-overlay-host-race-1"
D1219 09:01:17.978569   59112 x:0] Signal container "ci-gvisor-ptrace-direct-overlay-host-race-1": signal 0
D1219 09:01:17.978718   59112 x:0] Signal sandbox "ci-gvisor-ptrace-direct-overlay-host-race-1"
D1219 09:01:17.978802   59112 x:0] Connecting to sandbox "ci-gvisor-ptrace-direct-overlay-host-race-1"
D1219 09:01:17.979967   59112 x:0] urpc: successfully marshalled 123 bytes.
I1219 09:01:18.473921   59112 x:0] Found sandbox "ci-gvisor-ptrace-direct-overlay-host-race-1", PID: 35021
I1219 09:01:18.474060   59112 x:0] Retrieving sandbox stacks
D1219 09:01:18.474107   59112 x:0] Stacks sandbox "ci-gvisor-ptrace-direct-overlay-host-race-1"
D1219 09:01:18.474217   59112 x:0] Connecting to sandbox "ci-gvisor-ptrace-direct-overlay-host-race-1"
D1219 09:01:18.474475   59112 x:0] urpc: successfully marshalled 36 bytes.
W1219 09:01:18.663904   59112 x:0] FATAL ERROR: retrieving stacks: getting sandbox "ci-gvisor-ptrace-direct-overlay-host-race-1" stacks: urpc method "debug.Stacks" failed: connection reset by peer
retrieving stacks: getting sandbox "ci-gvisor-ptrace-direct-overlay-host-race-1" stacks: urpc method "debug.Stacks" failed: connection reset by peer
W1219 09:01:18.664337   59112 x:0] Failure to execute command, err: 1