On Tue, Mar 31, 2026 at 12:09:42AM +0800, WANG Rui wrote: > Given the diversity of filesystems in use, each one requires dedicated > engineering effort to implement and validate large folio support, and > that assumes both sufficient resources and prioritization on the > filesystem side. Even after support lands, coverage across different > base page sizes and configurations may take additional time to mature. > > What I am really concerned about is the transition period: if filesystem > support is not yet broadly ready, while we have already removed the > fallback path, we may end up in a situation where PMD-sized mappings > become effectively unavailable on many systems for some time. > > This is not about the long-term direction, but about the timing and > practical readiness.
If we leave this fallback in place, we'll never get filesystems to move forward. It's time to rip off this bandaid; they've got eight months before the next stable kernel. I've talked to them about it for years LSFMM 2022: https://lwn.net/Articles/893512/ LSFMM 2023: https://lwn.net/Articles/931794/ LSFMM 2024: https://lwn.net/Articles/973565/ LSFMM 2025: https://lwn.net/Articles/1015320/ (and earlier, but I think I've made my point)
