Writeback for filesystems is the process of flushing the "dirty" (written) data in the page cache to storage. At the 2025 Linux Storage, Filesystem, Memory Management, and BPF Summit (LSFMM+BPF), Anuj Gupta led a combined storage and filesystem session on some work that has been done to parallelize the writeback process. Some of the performance problems that have been seen with the existing single-threaded writeback came up in a session at last year's summit, where the idea of doing writeback in parallel was discussed.