During July 2025, Yifan Du focused on enhancing mempool stability in the geerlingguy/linux repository, addressing critical edge cases in kernel memory management. He resolved a crash in mempool_free for zero-minimum pools by introducing pointer guards and ensured that threads waiting on memory are properly awakened when memory is freed to an empty pool. His approach involved allocating at least one element for zero-minimum pools, simplifying dereferencing and handling in add_element. Working primarily in C, Yifan applied his expertise in kernel development and bug fixing to improve the reliability and maintainability of the mempool subsystem, reducing risks in low-memory scenarios.