On Tue, Jun 27, 2023 at 9:07 AM Peter Xu <peterx@xxxxxxxxxx> wrote:
On Mon, Jun 26, 2023 at 08:14:01PM -0700, Vishal Moola (Oracle) wrote:
Currently, page table information is stored within struct page. As part
of simplifying struct page, create struct ptdesc for page table
information.
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@xxxxxxxxx>
Acked-by: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
---
include/linux/pgtable.h | 68 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 68 insertions(+)
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 5063b482e34f..d46cb709ce08 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -987,6 +987,74 @@ static inline void ptep_modify_prot_commit(struct vm_area_struct *vma,
#endif /* __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION */
#endif /* CONFIG_MMU */
+
+/**
+ * struct ptdesc - Memory descriptor for page tables.
+ * @__page_flags: Same as page flags. Unused for page tables.
+ * @pt_rcu_head: For freeing page table pages.
+ * @pt_list: List of used page tables. Used for s390 and x86.
+ * @_pt_pad_1: Padding that aliases with page's compound head.
+ * @pmd_huge_pte: Protected by ptdesc->ptl, used for THPs.
+ * @_pt_s390_gaddr: Aliases with page's mapping. Used for s390 gmap only.
Should some arch-specific bits (and a few others) always under some
#ifdefs, so it shouldn't appear on other archs?
Right now this struct completely overlays struct page, so the padding as
well as any arch-specific fields have to stay. Whenever we get ptdescs
independent of struct page we can cleanup any unnecessary fields, as
well as omit unnecessary fields from unrelated architectures.
