Techniques are disclosed relating to memory page allocation for graphics processor. In some embodiments, a shader program includes a primary thread associated with ray tracing (that includes an instruction that indicates for the apparatus to launch one or more secondary threads). Memory resource allocator circuitry may receive a request to allocate a memory page in a page pool to a thread of the shader program, where the page pool includes a set of protected pages and a set of public pages. The allocator may allocate a page of the page pool to the requesting thread according to an allocation restriction, such that protected pages are allocable only to secondary threads that are launched based on a primary thread and public pages are allocable to both primary and secondary threads.