[PATCH v2 2/3] mm: drop pte_clear_not_present_full()

In general, there is no good reason to do anything special when clearing
non-present PTEs.

In theory, HW that does have to invalidate TLBs for non-present PTEs could
benefit from a "full" parameter, but fortunately
pte_clear_not_present_full() is not wired up anymore ... and there would
have to be something very convincing for us to care about that to re-add
it.

So, let's just use pte_clear() directly now. To avoid the compiler
complaining on some configs about unused "addr" parameter, silence that
here.

Reviewed-by: Oscar Salvador (SUSE) <[email protected]>
Signed-off-by: David Hildenbrand (Arm) <[email protected]>
---
 include/linux/pgtable.h | 21 ++++-----------------
 mm/madvise.c            |  4 ++--
 2 files changed, 6 insertions(+), 19 deletions(-)

diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index dc804296d78f7..0b81e396816a5 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -988,21 +988,6 @@ static inline void update_mmu_tlb(struct vm_area_struct *vma,
 	update_mmu_tlb_range(vma, address, ptep, 1);
 }
 
-/*
- * Some architectures may be able to avoid expensive synchronization
- * primitives when modifications are made to PTE's which are already
- * not present, or in the process of an address space destruction.
- */
-#ifndef __HAVE_ARCH_PTE_CLEAR_NOT_PRESENT_FULL
-static inline void pte_clear_not_present_full(struct mm_struct *mm,
-					      unsigned long address,
-					      pte_t *ptep,
-					      int full)
-{
-	pte_clear(mm, address, ptep);
-}
-#endif
-
 #ifndef clear_not_present_full_ptes
 /**
  * clear_not_present_full_ptes - Clear multiple not present PTEs which are
@@ -1014,7 +999,7 @@ static inline void pte_clear_not_present_full(struct mm_struct *mm,
  * @full: Whether we are clearing a full mm.
  *
  * May be overridden by the architecture; otherwise, implemented as a simple
- * loop over pte_clear_not_present_full().
+ * loop over pte_clear().
  *
  * Context: The caller holds the page table lock.  The PTEs are all not present.
  * The PTEs are all in the same PMD.
@@ -1022,8 +1007,10 @@ static inline void pte_clear_not_present_full(struct mm_struct *mm,
 static inline void clear_not_present_full_ptes(struct mm_struct *mm,
 		unsigned long addr, pte_t *ptep, unsigned int nr, int full)
 {
+	(void)addr;
+
 	for (;;) {
-		pte_clear_not_present_full(mm, addr, ptep, full);
+		pte_clear(mm, addr, ptep);
 		if (--nr == 0)
 			break;
 		ptep++;
diff --git a/mm/madvise.c b/mm/madvise.c
index cd9bb077072cc..f3cda54c1d6a0 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -698,7 +698,7 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
 				clear_not_present_full_ptes(mm, addr, pte, nr, tlb->fullmm);
 			} else if (softleaf_is_hwpoison(entry) ||
 				   softleaf_is_poison_marker(entry)) {
-				pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
+				pte_clear(mm, addr, pte);
 			}
 			continue;
 		}
@@ -1234,7 +1234,7 @@ static int guard_remove_pte_entry(pte_t *pte, unsigned long addr,
 
 	if (is_guard_pte_marker(ptent)) {
 		/* Simply clear the PTE marker. */
-		pte_clear_not_present_full(walk->mm, addr, pte, false);
+		pte_clear(walk->mm, addr, pte);
 		update_mmu_cache(walk->vma, addr, pte);
 	}
 

-- 
2.43.0