[PATCH v2 9/9] mm/huge_memory: have zap_huge_pmd() use vm_normal_folio_pmd()

[Lorenzo Stoakes (Oracle)]

Rather than having special handling for the 'special huge' and huge zero
pages, have vm_normal_folio_pmd() figure this out for us, and use the
presence of a folio to determine whether to exit early.

We can therefore delete code, move the 'present or not' logic up and make
things clearer this way.

Suggested-by: David Hildenbrand (ARM) <david@xxxxxxxxxx>
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@xxxxxxxxxx>
---
 mm/huge_memory.c | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 22715027e56c..5ffe3334c80d 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2431,9 +2431,9 @@ bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 		 pmd_t *pmd, unsigned long addr)
 {
 	bool needs_remove_rmap = false;
-	struct folio *folio = NULL;
 	bool needs_deposit = false;
 	bool is_present = false;
+	struct folio *folio;
 	spinlock_t *ptl;
 	pmd_t orig_pmd;
 
@@ -2453,28 +2453,26 @@ bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 
 	arch_check_zapped_pmd(vma, orig_pmd);
 	tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
-	if (vma_is_special_huge(vma))
-		goto out;
-	if (is_huge_zero_pmd(orig_pmd)) {
-		needs_deposit = !vma_is_dax(vma);
-		goto out;
-	}
 
-	is_present = pmd_present(orig_pmd);
-	if (is_present) {
-		folio = pmd_folio(orig_pmd);
-		needs_remove_rmap = true;
+	if (pmd_present(orig_pmd)) {
+		folio = vm_normal_folio_pmd(vma, addr, orig_pmd);
+		if (folio) {
+			needs_remove_rmap = true;
+			is_present = true;
+		} else if (is_huge_zero_pmd(orig_pmd)) {
+			needs_deposit = !vma_is_dax(vma);
+		}
 	} else if (pmd_is_valid_softleaf(orig_pmd)) {
-		const softleaf_t entry = softleaf_from_pmd(orig_pmd);
-
-		folio = softleaf_to_folio(entry);
+		folio = softleaf_to_folio(softleaf_from_pmd(orig_pmd));
 		needs_remove_rmap = folio_is_device_private(folio);
 		if (!thp_migration_supported())
 			WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
 	} else {
 		WARN_ON_ONCE(true);
-		goto out;
+		folio = NULL;
 	}
+	if (!folio)
+		goto out;
 
 	if (folio_test_anon(folio)) {
 		needs_deposit = true;
-- 
2.53.0