P4
`Arena::Amalloc` takes an `AllocFailType`.
`Amalloc` calls `Arena::grow` if there isn't sufficient space available in the already allocated chunk to satisfy the request, and passes the failure mode to `grow`.
`grow` calls `MemTracker::check_exceeds_limit`. If that call returns true, then `grow` returns nullptr, regardless of the requested failure mode.
Callers of `Amalloc` that pass `EXIT_OOM` as the failure mode are typically not prepared for a null allocation result, and at least some will crash.
`Amalloc` calls `Arena::grow` if there isn't sufficient space available in the already allocated chunk to satisfy the request, and passes the failure mode to `grow`.
`grow` calls `MemTracker::check_exceeds_limit`. If that call returns true, then `grow` returns nullptr, regardless of the requested failure mode.
Callers of `Amalloc` that pass `EXIT_OOM` as the failure mode are typically not prepared for a null allocation result, and at least some will crash.