Failures on [vm] If waiting for an active mutator slot for too long, steal a slot from a thread at a native safepoint.

[alexmarkov]

There are new test failures on [vm] If waiting for an active mutator slot for too long, steal a slot from a thread at a native safepoint..

The tests

vm/dart/isolates/many_isolates_blocked_at_ffi_test Timeout (expected Pass)
vm/dart/isolates/many_isolates_blocked_at_sleep_test Timeout (expected Pass)

are failing on configurations

vm-reload-linux-debug-x64
vm-reload-linux-release-x64
vm-reload-rollback-linux-debug-x64
vm-reload-rollback-linux-release-x64

@rmacnak-google Could you take a look?

[rmacnak-google]

Hm, native and FFI calls are at a GC safepoint and a deopt safepoint but not a reload safepoint.