Methods, systems, and devices for using page line filler data are described. In some examples, a memory system may store data within a write buffer of the memory system. The memory system may initiate an operation to transfer the write buffer data to a memory device, for example, due to a command to perform a memory management operation (e.g., cache synchronization, context switching, or the like) from a host system. In some examples, a quantity of write buffer data may fail to satisfy a data size threshold. Thus, the memory system may aggregate the data in the write buffer with valid data from a block of the memory device associated with garbage collection. The memory system may aggregate the write buffer data with the garbage collection data until the aggregated data satisfies the data size threshold. The memory system may then write the aggregated data to the memory device.