Re: [PATCH V3 0/5] mm/khugepaged: cleanups and scan limit fix

["Garg, Shivank" <shivankg@amd.com>]

On 1/19/2026 2:04 AM, Andrew Morton wrote:
> On Sun, 18 Jan 2026 19:22:51 +0000 Shivank Garg <shivankg@amd.com> wrote:
> 
>> This series contains several cleanups for mm/khugepaged.c to improve code
>> readability and type safety, and one functional fix to ensure
>> khugepaged_scan_mm_slot() correctly accounts for small VMAs towards
>> scan limit.
>>
> 
> That's a lot of changes to a well-reviewed 24 day old patchset.
> 

Sincere apologies for the last minute churn.

>>
>> v3:
>> - Fold mm-khugepaged-count-small-vmas-towards-scan-limit-fix: add comment (Lance)
>> - Remove extern and use two tabs indent (David) 
> 
> Are you sure?  The v2->v3 diff is large.  A lot of (unchangelogged)
> alterations from `int' to `enum scan_result'.
> 
> It all looks pretty simple/straightforward to me but again, can
> reviewers please check this over fairly soonly, thanks.
> 

The diff appears large because it somehow did not capture V2 Patch 4/5.

The correct V3 vs V2 diff changes: 

diff --git a/include/linux/khugepaged.h b/include/linux/khugepaged.h
index 37b992b22bba..d7a9053ff4fe 100644
--- a/include/linux/khugepaged.h
+++ b/include/linux/khugepaged.h
@@ -17,8 +17,8 @@ extern void khugepaged_enter_vma(struct vm_area_struct *vma,
 				 vm_flags_t vm_flags);
 extern void khugepaged_min_free_kbytes_update(void);
 extern bool current_is_khugepaged(void);
-extern void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
-				    bool install_pmd);
+void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
+		bool install_pmd);
 
 static inline void khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm)
 {
@@ -43,7 +43,7 @@ static inline void khugepaged_enter_vma(struct vm_area_struct *vma,
 {
 }
 static inline void collapse_pte_mapped_thp(struct mm_struct *mm,
-					   unsigned long addr, bool install_pmd)
+		unsigned long addr, bool install_pmd)
 {
 }
 
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 9f790ec34400..fba6aea5bea6 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -538,10 +538,8 @@ static void release_pte_pages(pte_t *pte, pte_t *_pte,
 }
 
 static enum scan_result __collapse_huge_page_isolate(struct vm_area_struct *vma,
-						     unsigned long start_addr,
-						     pte_t *pte,
-						     struct collapse_control *cc,
-						     struct list_head *compound_pagelist)
+		unsigned long start_addr, pte_t *pte, struct collapse_control *cc,
+		struct list_head *compound_pagelist)
 {
 	struct page *page = NULL;
 	struct folio *folio = NULL;
@@ -900,8 +898,7 @@ static int hpage_collapse_find_target_node(struct collapse_control *cc)
  */
 
 static enum scan_result hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
-						bool expect_anon, struct vm_area_struct **vmap,
-						struct collapse_control *cc)
+		bool expect_anon, struct vm_area_struct **vmap, struct collapse_control *cc)
 {
 	struct vm_area_struct *vma;
 	enum tva_type type = cc->is_khugepaged ? TVA_KHUGEPAGED :
@@ -954,8 +951,7 @@ static inline enum scan_result check_pmd_state(pmd_t *pmd)
 }
 
 static enum scan_result find_pmd_or_thp_or_none(struct mm_struct *mm,
-						unsigned long address,
-						pmd_t **pmd)
+		unsigned long address, pmd_t **pmd)
 {
 	*pmd = mm_find_pmd(mm, address);
 	if (!*pmd)
@@ -965,8 +961,7 @@ static enum scan_result find_pmd_or_thp_or_none(struct mm_struct *mm,
 }
 
 static enum scan_result check_pmd_still_valid(struct mm_struct *mm,
-					      unsigned long address,
-					      pmd_t *pmd)
+		unsigned long address, pmd_t *pmd)
 {
 	pmd_t *new_pmd;
 	enum scan_result result = find_pmd_or_thp_or_none(mm, address, &new_pmd);
@@ -986,9 +981,8 @@ static enum scan_result check_pmd_still_valid(struct mm_struct *mm,
  * Returns result: if not SCAN_SUCCEED, mmap_lock has been released.
  */
 static enum scan_result __collapse_huge_page_swapin(struct mm_struct *mm,
-						    struct vm_area_struct *vma,
-						    unsigned long start_addr, pmd_t *pmd,
-						    int referenced)
+		struct vm_area_struct *vma, unsigned long start_addr, pmd_t *pmd,
+		int referenced)
 {
 	int swapped_in = 0;
 	vm_fault_t ret = 0;
@@ -1063,7 +1057,7 @@ static enum scan_result __collapse_huge_page_swapin(struct mm_struct *mm,
 }
 
 static enum scan_result alloc_charge_folio(struct folio **foliop, struct mm_struct *mm,
-					   struct collapse_control *cc)
+		struct collapse_control *cc)
 {
 	gfp_t gfp = (cc->is_khugepaged ? alloc_hugepage_khugepaged_gfpmask() :
 		     GFP_TRANSHUGE);
@@ -1091,8 +1085,7 @@ static enum scan_result alloc_charge_folio(struct folio **foliop, struct mm_stru
 }
 
 static enum scan_result collapse_huge_page(struct mm_struct *mm, unsigned long address,
-					   int referenced, int unmapped,
-					   struct collapse_control *cc)
+		int referenced, int unmapped, struct collapse_control *cc)
 {
 	LIST_HEAD(compound_pagelist);
 	pmd_t *pmd, _pmd;
@@ -1247,9 +1240,8 @@ static enum scan_result collapse_huge_page(struct mm_struct *mm, unsigned long a
 }
 
 static enum scan_result hpage_collapse_scan_pmd(struct mm_struct *mm,
-						struct vm_area_struct *vma,
-						unsigned long start_addr, bool *mmap_locked,
-						struct collapse_control *cc)
+		struct vm_area_struct *vma, unsigned long start_addr, bool *mmap_locked,
+		struct collapse_control *cc)
 {
 	pmd_t *pmd;
 	pte_t *pte, *_pte;
@@ -1442,7 +1434,7 @@ static void collect_mm_slot(struct mm_slot *slot)
 
 /* folio must be locked, and mmap_lock must be held */
 static enum scan_result set_huge_pmd(struct vm_area_struct *vma, unsigned long addr,
-				     pmd_t *pmdp, struct folio *folio, struct page *page)
+		pmd_t *pmdp, struct folio *folio, struct page *page)
 {
 	struct mm_struct *mm = vma->vm_mm;
 	struct vm_fault vmf = {
@@ -1478,7 +1470,7 @@ static enum scan_result set_huge_pmd(struct vm_area_struct *vma, unsigned long a
 }
 
 static enum scan_result try_collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
-						    bool install_pmd)
+		bool install_pmd)
 {
 	enum scan_result result = SCAN_FAIL;
 	int nr_mapped_ptes = 0;
@@ -1713,7 +1705,7 @@ static enum scan_result try_collapse_pte_mapped_thp(struct mm_struct *mm, unsign
  * as pmd-mapped. Possibly install a huge PMD mapping the THP.
  */
 void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
-			     bool install_pmd)
+		bool install_pmd)
 {
 	try_collapse_pte_mapped_thp(mm, addr, install_pmd);
 }
@@ -1864,8 +1856,7 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff)
  *    + unlock and free huge page;
  */
 static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr,
-				      struct file *file, pgoff_t start,
-				      struct collapse_control *cc)
+		struct file *file, pgoff_t start, struct collapse_control *cc)
 {
 	struct address_space *mapping = file->f_mapping;
 	struct page *dst;
@@ -2296,8 +2287,7 @@ static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr,
 }
 
 static enum scan_result hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr,
-						 struct file *file, pgoff_t start,
-						 struct collapse_control *cc)
+		struct file *file, pgoff_t start, struct collapse_control *cc)
 {
 	struct folio *folio = NULL;
 	struct address_space *mapping = file->f_mapping;