[PATCH v1 3/4] mm/memory: pass folio and pte to restore_exclusive_pte()

[David Hildenbrand]

Let's pass the folio and the pte to restore_exclusive_pte(), so we
can avoid repeated page_folio() and ptep_get(). To do that,
pass the pte to try_restore_exclusive_pte() and use a folio in there
already.

While at it, just avoid the "swp_entry_t entry" variable in
try_restore_exclusive_pte() and add a folio-locked check to
restore_exclusive_pte().

Signed-off-by: David Hildenbrand <da...@redhat.com>
---
 mm/memory.c | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index cd689cd8a7c8..46956994aaff 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -719,14 +719,13 @@ struct folio *vm_normal_folio_pmd(struct vm_area_struct 
*vma,
 #endif
 
 static void restore_exclusive_pte(struct vm_area_struct *vma,
-                                 struct page *page, unsigned long address,
-                                 pte_t *ptep)
+               struct folio *folio, struct page *page, unsigned long address,
+               pte_t *ptep, pte_t orig_pte)
 {
-       struct folio *folio = page_folio(page);
-       pte_t orig_pte;
        pte_t pte;
 
-       orig_pte = ptep_get(ptep);
+       VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio);
+
        pte = pte_mkold(mk_pte(page, READ_ONCE(vma->vm_page_prot)));
        if (pte_swp_soft_dirty(orig_pte))
                pte = pte_mksoft_dirty(pte);
@@ -756,16 +755,15 @@ static void restore_exclusive_pte(struct vm_area_struct 
*vma,
  * Tries to restore an exclusive pte if the page lock can be acquired without
  * sleeping.
  */
-static int
-try_restore_exclusive_pte(pte_t *src_pte, struct vm_area_struct *vma,
-                       unsigned long addr)
+static int try_restore_exclusive_pte(struct vm_area_struct *vma,
+               unsigned long addr, pte_t *ptep, pte_t orig_pte)
 {
-       swp_entry_t entry = pte_to_swp_entry(ptep_get(src_pte));
-       struct page *page = pfn_swap_entry_to_page(entry);
+       struct page *page = pfn_swap_entry_to_page(pte_to_swp_entry(orig_pte));
+       struct folio *folio = page_folio(page);
 
-       if (trylock_page(page)) {
-               restore_exclusive_pte(vma, page, addr, src_pte);
-               unlock_page(page);
+       if (folio_trylock(folio)) {
+               restore_exclusive_pte(vma, folio, page, addr, ptep, orig_pte);
+               folio_unlock(folio);
                return 0;
        }
 
@@ -871,7 +869,7 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct 
mm_struct *src_mm,
                 * (ie. COW) mappings.
                 */
                VM_BUG_ON(!is_cow_mapping(src_vma->vm_flags));
-               if (try_restore_exclusive_pte(src_pte, src_vma, addr))
+               if (try_restore_exclusive_pte(src_vma, addr, src_pte, orig_pte))
                        return -EBUSY;
                return -ENOENT;
        } else if (is_pte_marker_entry(entry)) {
@@ -3979,7 +3977,8 @@ static vm_fault_t remove_device_exclusive_entry(struct 
vm_fault *vmf)
        vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
                                &vmf->ptl);
        if (likely(vmf->pte && pte_same(ptep_get(vmf->pte), vmf->orig_pte)))
-               restore_exclusive_pte(vma, vmf->page, vmf->address, vmf->pte);
+               restore_exclusive_pte(vma, folio, vmf->page, vmf->address,
+                                     vmf->pte, vmf->orig_pte);
 
        if (vmf->pte)
                pte_unmap_unlock(vmf->pte, vmf->ptl);
-- 
2.48.1