On 9/8/26 8:50 PM, Kiryl Shutsemau wrote:
From: "Kiryl Shutsemau (Meta)" <[email protected]> The page cache caps folio order at MAX_PAGECACHE_ORDER, which is below the PMD order on arm64 with 64K pages, where a PMD is 512M. A PMD-sized page cache folio is impossible there, so the kernel refuses these collapses: MADV_COLLAPSE answers -EINVAL and khugepaged passes over the range. Four shmem cases ask for a PMD-sized folio anyway, fail, and the run bails out in the middle. Skip the shmem and file mem types where the cap is below the PMD order. The cap is not shmem-specific: it applies to every file folio. Add thp_file_supported_orders() to read the orders the page cache allows. Anonymous collapse is unaffected: its orders are not capped this way. Assisted-by: LLM Reviewed-by: Mike Rapoport (Microsoft) <[email protected]> Tested-by: Muhammad Usama Anjum <[email protected]> Signed-off-by: Kiryl Shutsemau (Meta) <[email protected]> ---
LGTM. Reviewed-by: Baolin Wang <[email protected]>
