The kstress command runs VM stress tests. Some VM stress tests use syscalls from the next vDSO, and so need to be run as a component with the use_next_vdso flag. Therefore the VM stress tests should be run as the test component vm-stress-test.cm instead of using the kstress command directly at the shell prompt.
Build and run the test component like so:
fx set core.x64 --with src/zircon/tests/stress-tests:tests fx build fx qemu fx test vm-stress-test