Re: [PATCH mm-new v3 3/3] mm/khugepaged: merge PTE scanning logic into a new helper

[Andrew Morton <akpm@linux-foundation.org>]

On Wed,  8 Oct 2025 12:37:48 +0800 Lance Yang <lance.yang@linux.dev> wrote:

> +		if (!cc->is_khugepaged ||
> +		    *unmapped <= khugepaged_max_ptes_swap) {
> +			/*
> +			 * Always be strict with uffd-wp enabled swap
> +			 * entries. Please see comment below for
> +			 * pte_uffd_wp().
> +			 */
> +			if (pte_swp_uffd_wp(pte)) {
> +				*scan_result = SCAN_PTE_UFFD_WP;
> +				return PTE_CHECK_FAIL;
> +			}
> +			return PTE_CHECK_CONTINUE;
> +		} else {
> +			*scan_result = SCAN_EXCEED_SWAP_PTE;
> +			count_vm_event(THP_SCAN_EXCEED_SWAP_PTE);
> +			return PTE_CHECK_FAIL;
> +		}

I'm inclined to agree with checkpatch here.

WARNING: else is not generally useful after a break or return
#81: FILE: mm/khugepaged.c:574:
+			return PTE_CHECK_CONTINUE;
+		} else {

did you see this and disagree or did you forget to run checkpatch?

--- a/mm/khugepaged.c~mm-khugepaged-merge-pte-scanning-logic-into-a-new-helper-checkpatch-fixes
+++ a/mm/khugepaged.c
@@ -571,11 +571,10 @@ static inline int thp_collapse_check_pte
 		    (!cc->is_khugepaged ||
 		     *none_or_zero <= khugepaged_max_ptes_none)) {
 			return PTE_CHECK_CONTINUE;
-		} else {
-			*scan_result = SCAN_EXCEED_NONE_PTE;
-			count_vm_event(THP_SCAN_EXCEED_NONE_PTE);
-			return PTE_CHECK_FAIL;
 		}
+		*scan_result = SCAN_EXCEED_NONE_PTE;
+		count_vm_event(THP_SCAN_EXCEED_NONE_PTE);
+		return PTE_CHECK_FAIL;
 	} else if (!pte_present(pte)) {
 		if (!unmapped) {
 			*scan_result = SCAN_PTE_NON_PRESENT;
@@ -600,11 +599,10 @@ static inline int thp_collapse_check_pte
 				return PTE_CHECK_FAIL;
 			}
 			return PTE_CHECK_CONTINUE;
-		} else {
-			*scan_result = SCAN_EXCEED_SWAP_PTE;
-			count_vm_event(THP_SCAN_EXCEED_SWAP_PTE);
-			return PTE_CHECK_FAIL;
 		}
+		*scan_result = SCAN_EXCEED_SWAP_PTE;
+		count_vm_event(THP_SCAN_EXCEED_SWAP_PTE);
+		return PTE_CHECK_FAIL;
 	} else if (pte_uffd_wp(pte)) {
 		/*
 		 * Don't collapse the page if any of the small PTEs are
_