On 8/31/26 3:53 PM, Muchun Song wrote:
Device DAX still uses vmemmap_populate_compound_pages() to populate its compound-page vmemmap mappings. That helper allocates the head and first tail vmemmap pages explicitly, then reuses the first tail page for the remaining tail page mappings. Device DAX is being moved to the section-based vmemmap optimization infrastructure, but it cannot switch to the generic section-based population path yet. Once a later patch records the DAX compound-page geometry in the section order, DAX head and first-tail PFNs can look optimizable to the generic helpers as well. Add a DAX-specific population flag for this transition. It keeps DAX head/first-tail allocations on the normal vmemmap allocation path, while preserving the existing page reference for reused DAX tail mappings. Signed-off-by: Muchun Song <[email protected]> --- mm/sparse-vmemmap.c | 27 +++++++++++++++------------ 1 file changed, 15 insertions(+), 12 deletions(-)
Acked-by: Qi Zheng <[email protected]> Thanks, Qi
