[PATCH 3/8] mm/khugepaged: introduce a count_collapse_event() helper

[Nico Pache]

Provide a simple helper function to help reduce a often used, and
duplicate pattern across the khugepaged code.

When collapsing to a PMD we need to record a vm_event and the mTHP_stat
event. When doing mTHP collapse we only update the mTHP stat.

Signed-off-by: Nico Pache <npache@xxxxxxxxxx>
---
 mm/khugepaged.c | 36 ++++++++++++++++++------------------
 1 file changed, 18 insertions(+), 18 deletions(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 48b008a3c891..7047253a6fb6 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -692,6 +692,14 @@ static inline bool collapse_is_young(struct collapse_control *cc, pte_t pteval,
 		mmu_notifier_test_young(vma->vm_mm, addr));
 }
 
+static void count_collapse_event(unsigned int order, enum vm_event_item vm_event,
+		enum mthp_stat_item mthp_event)
+{
+	if (is_pmd_order(order))
+		count_vm_event(vm_event);
+	count_mthp_stat(order, mthp_event);
+}
+
 static enum scan_result __collapse_huge_page_isolate(struct vm_area_struct *vma,
 		unsigned long start_addr, pte_t *pte, struct collapse_control *cc,
 		unsigned int order, struct list_head *compound_pagelist)
@@ -712,9 +720,8 @@ static enum scan_result __collapse_huge_page_isolate(struct vm_area_struct *vma,
 		if (pte_none_or_zero(pteval)) {
 			if (++none_or_zero > max_ptes_none) {
 				result = SCAN_EXCEED_NONE_PTE;
-				if (is_pmd_order(order))
-					count_vm_event(THP_SCAN_EXCEED_NONE_PTE);
-				count_mthp_stat(order, MTHP_STAT_COLLAPSE_EXCEED_NONE);
+				count_collapse_event(order, THP_SCAN_EXCEED_NONE_PTE,
+						MTHP_STAT_COLLAPSE_EXCEED_NONE);
 				goto out;
 			}
 			continue;
@@ -756,9 +763,8 @@ static enum scan_result __collapse_huge_page_isolate(struct vm_area_struct *vma,
 			 */
 			if (++shared > max_ptes_shared) {
 				result = SCAN_EXCEED_SHARED_PTE;
-				if (is_pmd_order(order))
-					count_vm_event(THP_SCAN_EXCEED_SHARED_PTE);
-				count_mthp_stat(order, MTHP_STAT_COLLAPSE_EXCEED_SHARED);
+				count_collapse_event(order, THP_SCAN_EXCEED_SHARED_PTE,
+						MTHP_STAT_COLLAPSE_EXCEED_SHARED);
 				goto out;
 			}
 		}
@@ -1267,15 +1273,12 @@ static enum scan_result alloc_charge_folio(struct folio **foliop, struct mm_stru
 	folio = __folio_alloc(gfp, order, node, &cc->alloc_nmask);
 	if (!folio) {
 		*foliop = NULL;
-		if (is_pmd_order(order))
-			count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
-		count_mthp_stat(order, MTHP_STAT_COLLAPSE_ALLOC_FAILED);
+		count_collapse_event(order, THP_COLLAPSE_ALLOC_FAILED,
+				MTHP_STAT_COLLAPSE_ALLOC_FAILED);
 		return SCAN_ALLOC_HUGE_PAGE_FAIL;
 	}
 
-	if (is_pmd_order(order))
-		count_vm_event(THP_COLLAPSE_ALLOC);
-	count_mthp_stat(order, MTHP_STAT_COLLAPSE_ALLOC);
+	count_collapse_event(order, THP_COLLAPSE_ALLOC, MTHP_STAT_COLLAPSE_ALLOC);
 
 	if (unlikely(mem_cgroup_charge(folio, mm, gfp))) {
 		folio_put(folio);
@@ -1665,8 +1668,7 @@ static enum scan_result collapse_scan_pmd(struct mm_struct *mm,
 		if (pte_none_or_zero(pteval)) {
 			if (++none_or_zero > max_ptes_none) {
 				result = SCAN_EXCEED_NONE_PTE;
-				count_vm_event(THP_SCAN_EXCEED_NONE_PTE);
-				count_mthp_stat(HPAGE_PMD_ORDER,
+				count_collapse_event(HPAGE_PMD_ORDER, THP_SCAN_EXCEED_NONE_PTE,
 						MTHP_STAT_COLLAPSE_EXCEED_NONE);
 				goto out_unmap;
 			}
@@ -1675,8 +1677,7 @@ static enum scan_result collapse_scan_pmd(struct mm_struct *mm,
 		if (!pte_present(pteval)) {
 			if (++unmapped > max_ptes_swap) {
 				result = SCAN_EXCEED_SWAP_PTE;
-				count_vm_event(THP_SCAN_EXCEED_SWAP_PTE);
-				count_mthp_stat(HPAGE_PMD_ORDER,
+				count_collapse_event(HPAGE_PMD_ORDER, THP_SCAN_EXCEED_SWAP_PTE,
 						MTHP_STAT_COLLAPSE_EXCEED_SWAP);
 				goto out_unmap;
 			}
@@ -1734,8 +1735,7 @@ static enum scan_result collapse_scan_pmd(struct mm_struct *mm,
 		if (folio_maybe_mapped_shared(folio)) {
 			if (++shared > max_ptes_shared) {
 				result = SCAN_EXCEED_SHARED_PTE;
-				count_vm_event(THP_SCAN_EXCEED_SHARED_PTE);
-				count_mthp_stat(HPAGE_PMD_ORDER,
+				count_collapse_event(HPAGE_PMD_ORDER, THP_SCAN_EXCEED_SHARED_PTE,
 						MTHP_STAT_COLLAPSE_EXCEED_SHARED);
 				goto out_unmap;
 			}
-- 
2.54.0