[RFC PATCH 10/12] mm: remove remaining is_swap_pmd() users and is_swap_pmd()

[Lorenzo Stoakes <lorenzo.stoakes@oracle.com>]

Update copy_huge_pmd() and change_huge_pmd() to use
is_pmd_non_present_folio_entry() - as this checks for the only valid
non-present huge PMD states.

Also update mm/debug_vm_pgtable.c to explicitly test for a valid
non-present PMD entry (which it was not before, which was incorrect), and
have it test against is_huge_pmd() and is_pmd_non_present_folio_entry()
rather than is_swap_pmd().

With these changes done there are no further users of is_swap_pmd(), so
remove it.

Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
---
 include/linux/huge_mm.h |  9 ---------
 mm/debug_vm_pgtable.c   | 25 +++++++++++++++----------
 mm/huge_memory.c        |  5 +++--
 3 files changed, 18 insertions(+), 21 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 892cb825dfc7..0c3a002dc10f 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -484,11 +484,6 @@ void vma_adjust_trans_huge(struct vm_area_struct *vma, unsigned long start,
 spinlock_t *__pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma);
 spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma);
 
-static inline int is_swap_pmd(pmd_t pmd)
-{
-	return !pmd_none(pmd) && !pmd_present(pmd);
-}
-
 /* mmap_lock must be held on entry */
 static inline spinlock_t *pmd_trans_huge_lock(pmd_t *pmd,
 		struct vm_area_struct *vma)
@@ -684,10 +679,6 @@ static inline void vma_adjust_trans_huge(struct vm_area_struct *vma,
 					 struct vm_area_struct *next)
 {
 }
-static inline int is_swap_pmd(pmd_t pmd)
-{
-	return 0;
-}
 static inline spinlock_t *pmd_trans_huge_lock(pmd_t *pmd,
 		struct vm_area_struct *vma)
 {
diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index d4b2835569ce..5b8b0024a492 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -74,6 +74,7 @@ struct pgtable_debug_args {
 	unsigned long		fixed_pte_pfn;
 
 	swp_entry_t		swp_entry;
+	swp_entry_t		non_present_swp_entry;
 };
 
 static void __init pte_basic_tests(struct pgtable_debug_args *args, int idx)
@@ -731,7 +732,7 @@ static void __init pmd_soft_dirty_tests(struct pgtable_debug_args *args)
 	WARN_ON(pmd_soft_dirty(pmd_clear_soft_dirty(pmd)));
 }
 
-static void __init pmd_swap_soft_dirty_tests(struct pgtable_debug_args *args)
+static void __init pmd_non_present_soft_dirty_tests(struct pgtable_debug_args *args)
 {
 	pmd_t pmd;
 
@@ -743,15 +744,16 @@ static void __init pmd_swap_soft_dirty_tests(struct pgtable_debug_args *args)
 		return;
 
 	pr_debug("Validating PMD swap soft dirty\n");
-	pmd = swp_entry_to_pmd(args->swp_entry);
-	WARN_ON(!is_swap_pmd(pmd));
+	pmd = swp_entry_to_pmd(args->non_present_swp_entry);
+	WARN_ON(!is_huge_pmd(pmd));
+	WARN_ON(!is_pmd_non_present_folio_entry(pmd));
 
 	WARN_ON(!pmd_swp_soft_dirty(pmd_swp_mksoft_dirty(pmd)));
 	WARN_ON(pmd_swp_soft_dirty(pmd_swp_clear_soft_dirty(pmd)));
 }
 #else  /* !CONFIG_TRANSPARENT_HUGEPAGE */
 static void __init pmd_soft_dirty_tests(struct pgtable_debug_args *args) { }
-static void __init pmd_swap_soft_dirty_tests(struct pgtable_debug_args *args) { }
+static void __init pmd_non_present_soft_dirty_tests(struct pgtable_debug_args *args) { }
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
 static void __init pte_swap_exclusive_tests(struct pgtable_debug_args *args)
@@ -796,7 +798,7 @@ static void __init pte_swap_tests(struct pgtable_debug_args *args)
 }
 
 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
-static void __init pmd_swap_tests(struct pgtable_debug_args *args)
+static void __init pmd_non_present_tests(struct pgtable_debug_args *args)
 {
 	swp_entry_t arch_entry;
 	pmd_t pmd1, pmd2;
@@ -805,15 +807,16 @@ static void __init pmd_swap_tests(struct pgtable_debug_args *args)
 		return;
 
 	pr_debug("Validating PMD swap\n");
-	pmd1 = swp_entry_to_pmd(args->swp_entry);
-	WARN_ON(!is_swap_pmd(pmd1));
+	pmd1 = swp_entry_to_pmd(args->non_present_swp_entry);
+	WARN_ON(!is_huge_pmd(pmd1));
+	WARN_ON(!is_pmd_non_present_folio_entry(pmd1));
 
 	arch_entry = __pmd_to_swp_entry(pmd1);
 	pmd2 = __swp_entry_to_pmd(arch_entry);
 	WARN_ON(memcmp(&pmd1, &pmd2, sizeof(pmd1)));
 }
 #else  /* !CONFIG_ARCH_ENABLE_THP_MIGRATION */
-static void __init pmd_swap_tests(struct pgtable_debug_args *args) { }
+static void __init pmd_non_present_tests(struct pgtable_debug_args *args) { }
 #endif /* CONFIG_ARCH_ENABLE_THP_MIGRATION */
 
 static void __init swap_migration_tests(struct pgtable_debug_args *args)
@@ -1207,6 +1210,8 @@ static int __init init_args(struct pgtable_debug_args *args)
 	max_swap_offset = swp_offset(pte_to_swp_entry(swp_entry_to_pte(swp_entry(0, ~0UL))));
 	/* Create a swp entry with all possible bits set while still being swap. */
 	args->swp_entry = swp_entry(MAX_SWAPFILES - 1, max_swap_offset);
+	/* Create a non-present migration entry. */
+	args->non_present_swp_entry = make_writable_migration_entry(~0UL);
 
 	/*
 	 * Allocate (huge) pages because some of the tests need to access
@@ -1296,12 +1301,12 @@ static int __init debug_vm_pgtable(void)
 	pte_soft_dirty_tests(&args);
 	pmd_soft_dirty_tests(&args);
 	pte_swap_soft_dirty_tests(&args);
-	pmd_swap_soft_dirty_tests(&args);
+	pmd_non_present_soft_dirty_tests(&args);
 
 	pte_swap_exclusive_tests(&args);
 
 	pte_swap_tests(&args);
-	pmd_swap_tests(&args);
+	pmd_non_present_tests(&args);
 
 	swap_migration_tests(&args);
 
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index fa928ca42b6d..a16da67684b4 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1874,7 +1874,8 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 	ret = -EAGAIN;
 	pmd = *src_pmd;
 
-	if (unlikely(thp_migration_supported() && is_swap_pmd(pmd))) {
+	if (unlikely(thp_migration_supported() &&
+		     is_pmd_non_present_folio_entry(pmd))) {
 		copy_huge_non_present_pmd(dst_mm, src_mm, dst_pmd, src_pmd, addr,
 					  dst_vma, src_vma, pmd, pgtable);
 		ret = 0;
@@ -2562,7 +2563,7 @@ int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 	if (!ptl)
 		return 0;
 
-	if (thp_migration_supported() && is_swap_pmd(*pmd)) {
+	if (thp_migration_supported() && is_pmd_non_present_folio_entry(*pmd)) {
 		change_non_present_huge_pmd(mm, addr, pmd, uffd_wp,
 					    uffd_wp_resolve);
 		goto unlock;
-- 
2.51.0