On Fri, Jun 05, 2026 at 10:14:13AM -0600, Nico Pache wrote: >Pass an order to collapse_huge_page to support collapsing anon memory to >arbitrary orders within a PMD. order indicates what mTHP size we are >attempting to collapse to. > >For non-PMD collapse we must leave the anon VMA write locked until after >we collapse the mTHP-- in the PMD case all the pages are isolated, but in >the mTHP case this is not true, and we must keep the lock to prevent >access/changes to the page tables. This can happen if the rmap walkers hit >a pmd_none while the PMD entry is currently unavailable due to being >temporarily removed during the collapse phase. > >To properly establish the page table hierarchy without violating any >expectations from certain architectures (e.g. MIPS), we must make sure to >have the PMD reinstalled before the PTEs, and hold both PTE/PMD locks >before calling update_mmu_cache_range() (if they are distinct locks). > >Signed-off-by: Nico Pache <[email protected]> >---
Nothing else jumped out at me. Anything left can be sorted out later, as David and Lorenzo said :) Reviewed-by: Lance Yang <[email protected]>
