mm/khugepaged: use enum scan_result for result variables and return types

Convert result variables and return types from int to enum scan_result
throughout khugepaged code.  This improves type safety and code clarity by
making the intent explicit.

No functional change.

Link: https://lkml.kernel.org/r/20260118192253.9263-12-shivankg@amd.com
Signed-off-by: Shivank Garg <shivankg@amd.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Tested-by: Nico Pache <npache@redhat.com>
Reviewed-by: Nico Pache <npache@redhat.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index d513375b4f39083e222feece87e3a13c21a98854..c0a29a85230a0e34d2ef51b88bee841081c3b43d 100644 (file)
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -537,17 +537,16 @@ static void release_pte_pages(pte_t *pte, pte_t *_pte,
        }
 }
 
-static int __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)
+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)
 {
        struct page *page = NULL;
        struct folio *folio = NULL;
        unsigned long addr = start_addr;
        pte_t *_pte;
-       int none_or_zero = 0, shared = 0, result = SCAN_FAIL, referenced = 0;
+       int none_or_zero = 0, shared = 0, referenced = 0;
+       enum scan_result result = SCAN_FAIL;
 
        for (_pte = pte; _pte < pte + HPAGE_PMD_NR;
             _pte++, addr += PAGE_SIZE) {
@@ -780,13 +779,13 @@ static void __collapse_huge_page_copy_failed(pte_t *pte,
  * @ptl: lock on raw pages' PTEs
  * @compound_pagelist: list that stores compound pages
  */
-static int __collapse_huge_page_copy(pte_t *pte, struct folio *folio,
+static enum scan_result __collapse_huge_page_copy(pte_t *pte, struct folio *folio,
                pmd_t *pmd, pmd_t orig_pmd, struct vm_area_struct *vma,
                unsigned long address, spinlock_t *ptl,
                struct list_head *compound_pagelist)
 {
        unsigned int i;
-       int result = SCAN_SUCCEED;
+       enum scan_result result = SCAN_SUCCEED;
 
        /*
         * Copying pages' contents is subject to memory poison at any iteration.
@@ -898,10 +897,8 @@ static int hpage_collapse_find_target_node(struct collapse_control *cc)
  * Returns enum scan_result value.
  */
 
-static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
-                                  bool expect_anon,
-                                  struct vm_area_struct **vmap,
-                                  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)
 {
        struct vm_area_struct *vma;
        enum tva_type type = cc->is_khugepaged ? TVA_KHUGEPAGED :
@@ -930,7 +927,7 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
        return SCAN_SUCCEED;
 }
 
-static inline int check_pmd_state(pmd_t *pmd)
+static inline enum scan_result check_pmd_state(pmd_t *pmd)
 {
        pmd_t pmde = pmdp_get_lockless(pmd);
 
@@ -953,9 +950,8 @@ static inline int check_pmd_state(pmd_t *pmd)
        return SCAN_SUCCEED;
 }
 
-static int find_pmd_or_thp_or_none(struct mm_struct *mm,
-                                  unsigned long address,
-                                  pmd_t **pmd)
+static enum scan_result find_pmd_or_thp_or_none(struct mm_struct *mm,
+               unsigned long address, pmd_t **pmd)
 {
        *pmd = mm_find_pmd(mm, address);
        if (!*pmd)
@@ -964,12 +960,11 @@ static int find_pmd_or_thp_or_none(struct mm_struct *mm,
        return check_pmd_state(*pmd);
 }
 
-static int check_pmd_still_valid(struct mm_struct *mm,
-                                unsigned long address,
-                                pmd_t *pmd)
+static enum scan_result check_pmd_still_valid(struct mm_struct *mm,
+               unsigned long address, pmd_t *pmd)
 {
        pmd_t *new_pmd;
-       int result = find_pmd_or_thp_or_none(mm, address, &new_pmd);
+       enum scan_result result = find_pmd_or_thp_or_none(mm, address, &new_pmd);
 
        if (result != SCAN_SUCCEED)
                return result;
@@ -985,15 +980,14 @@ static int check_pmd_still_valid(struct mm_struct *mm,
  * Called and returns without pte mapped or spinlocks held.
  * Returns result: if not SCAN_SUCCEED, mmap_lock has been released.
  */
-static int __collapse_huge_page_swapin(struct mm_struct *mm,
-                                      struct vm_area_struct *vma,
-                                      unsigned long start_addr, pmd_t *pmd,
-                                      int referenced)
+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)
 {
        int swapped_in = 0;
        vm_fault_t ret = 0;
        unsigned long addr, end = start_addr + (HPAGE_PMD_NR * PAGE_SIZE);
-       int result;
+       enum scan_result result;
        pte_t *pte = NULL;
        spinlock_t *ptl;
 
@@ -1062,8 +1056,8 @@ out:
        return result;
 }
 
-static int alloc_charge_folio(struct folio **foliop, struct mm_struct *mm,
-                             struct collapse_control *cc)
+static enum scan_result alloc_charge_folio(struct folio **foliop, struct mm_struct *mm,
+               struct collapse_control *cc)
 {
        gfp_t gfp = (cc->is_khugepaged ? alloc_hugepage_khugepaged_gfpmask() :
                     GFP_TRANSHUGE);
@@ -1090,9 +1084,8 @@ static int alloc_charge_folio(struct folio **foliop, struct mm_struct *mm,
        return SCAN_SUCCEED;
 }
 
-static int collapse_huge_page(struct mm_struct *mm, unsigned long address,
-                             int referenced, int unmapped,
-                             struct collapse_control *cc)
+static enum scan_result collapse_huge_page(struct mm_struct *mm, unsigned long address,
+               int referenced, int unmapped, struct collapse_control *cc)
 {
        LIST_HEAD(compound_pagelist);
        pmd_t *pmd, _pmd;
@@ -1100,7 +1093,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address,
        pgtable_t pgtable;
        struct folio *folio;
        spinlock_t *pmd_ptl, *pte_ptl;
-       int result = SCAN_FAIL;
+       enum scan_result result = SCAN_FAIL;
        struct vm_area_struct *vma;
        struct mmu_notifier_range range;
 
@@ -1246,15 +1239,14 @@ out_nolock:
        return result;
 }
 
-static int hpage_collapse_scan_pmd(struct mm_struct *mm,
-                                  struct vm_area_struct *vma,
-                                  unsigned long start_addr, bool *mmap_locked,
-                                  struct collapse_control *cc)
+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)
 {
        pmd_t *pmd;
        pte_t *pte, *_pte;
-       int result = SCAN_FAIL, referenced = 0;
-       int none_or_zero = 0, shared = 0;
+       int none_or_zero = 0, shared = 0, referenced = 0;
+       enum scan_result result = SCAN_FAIL;
        struct page *page = NULL;
        struct folio *folio = NULL;
        unsigned long addr;
@@ -1441,8 +1433,8 @@ static void collect_mm_slot(struct mm_slot *slot)
 }
 
 /* folio must be locked, and mmap_lock must be held */
-static int set_huge_pmd(struct vm_area_struct *vma, unsigned long addr,
-                       pmd_t *pmdp, struct folio *folio, struct page *page)
+static enum scan_result set_huge_pmd(struct vm_area_struct *vma, unsigned long addr,
+               pmd_t *pmdp, struct folio *folio, struct page *page)
 {
        struct mm_struct *mm = vma->vm_mm;
        struct vm_fault vmf = {
@@ -1477,10 +1469,11 @@ static int set_huge_pmd(struct vm_area_struct *vma, unsigned long addr,
        return SCAN_SUCCEED;
 }
 
-static int try_collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
+static enum scan_result try_collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
                bool install_pmd)
 {
-       int nr_mapped_ptes = 0, result = SCAN_FAIL;
+       enum scan_result result = SCAN_FAIL;
+       int nr_mapped_ptes = 0;
        unsigned int nr_batch_ptes;
        struct mmu_notifier_range range;
        bool notified = false;
@@ -1862,9 +1855,8 @@ drop_pml:
  *    + unlock old pages
  *    + unlock and free huge page;
  */
-static int collapse_file(struct mm_struct *mm, unsigned long addr,
-                        struct file *file, pgoff_t start,
-                        struct collapse_control *cc)
+static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr,
+               struct file *file, pgoff_t start, struct collapse_control *cc)
 {
        struct address_space *mapping = file->f_mapping;
        struct page *dst;
@@ -1872,7 +1864,8 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
        pgoff_t index = 0, end = start + HPAGE_PMD_NR;
        LIST_HEAD(pagelist);
        XA_STATE_ORDER(xas, &mapping->i_pages, start, HPAGE_PMD_ORDER);
-       int nr_none = 0, result = SCAN_SUCCEED;
+       enum scan_result result = SCAN_SUCCEED;
+       int nr_none = 0;
        bool is_shmem = shmem_file(file);
 
        VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem);
@@ -2293,16 +2286,15 @@ out:
        return result;
 }
 
-static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr,
-                                   struct file *file, pgoff_t start,
-                                   struct collapse_control *cc)
+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 folio *folio = NULL;
        struct address_space *mapping = file->f_mapping;
        XA_STATE(xas, &mapping->i_pages, start);
        int present, swap;
        int node = NUMA_NO_NODE;
-       int result = SCAN_SUCCEED;
+       enum scan_result result = SCAN_SUCCEED;
 
        present = 0;
        swap = 0;
@@ -2400,7 +2392,7 @@ static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr,
        return result;
 }
 
-static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
+static unsigned int khugepaged_scan_mm_slot(unsigned int pages, enum scan_result *result,
                                            struct collapse_control *cc)
        __releases(&khugepaged_mm_lock)
        __acquires(&khugepaged_mm_lock)
@@ -2561,7 +2553,7 @@ static void khugepaged_do_scan(struct collapse_control *cc)
        unsigned int progress = 0, pass_through_head = 0;
        unsigned int pages = READ_ONCE(khugepaged_pages_to_scan);
        bool wait = true;
-       int result = SCAN_SUCCEED;
+       enum scan_result result = SCAN_SUCCEED;
 
        lru_add_drain_all();
 
@@ -2774,7 +2766,8 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start,
        struct collapse_control *cc;
        struct mm_struct *mm = vma->vm_mm;
        unsigned long hstart, hend, addr;
-       int thps = 0, last_fail = SCAN_FAIL;
+       enum scan_result last_fail = SCAN_FAIL;
+       int thps = 0;
        bool mmap_locked = true;
 
        BUG_ON(vma->vm_start > start);
@@ -2795,7 +2788,7 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start,
        hend = end & HPAGE_PMD_MASK;
 
        for (addr = hstart; addr < hend; addr += HPAGE_PMD_SIZE) {
-               int result = SCAN_FAIL;
+               enum scan_result result = SCAN_FAIL;
                bool triggered_wb = false;
 
 retry: