Hi Lorenzo, sorry for only replying to this so late. On Fri, Sep 27, 2024 at 01:51:11PM +0100, Lorenzo Stoakes wrote: > The existing generic pagewalk logic permits the walking of page tables, > invoking callbacks at individual page table levels via user-provided > mm_walk_ops callbacks. > > This is useful for traversing existing page table entries, but precludes > the ability to establish new ones. > > Existing mechanism for performing a walk which also installs page table > entries if necessary are heavily duplicated throughout the kernel, each > with semantic differences from one another and largely unavailable for use > elsewhere. I do like the idea of having common code for installing page tables! Minor nits below: > +int walk_page_range_mm(struct mm_struct *mm, unsigned long start, > unsigned long end, const struct mm_walk_ops *ops, > void *private) It would be good to have a minimum level of documentation for this function, including how it differs from walk_page_range and why it should remain internal. > + /* For internal use only. */ > + if (ops->install_pte) > + return -EINVAL; And this should probably be expanded a bit, including that no exported symbol should allow inserting arbitrary PTEs. Maybe best done with a helper to share that comment with the other places that have this check.
