[PATCH v3 12/16] mm: remove remaining is_swap_pmd() users and is_swap_pmd()

Lorenzo Stoakes
2025-11-10T22:24:13Z

Update copy_huge_pmd() and change_huge_pmd() to use pmd_is_valid_softleaf()
- 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 leaf PMD
entry (which it was not before, which was incorrect), and have it test
against pmd_is_huge() and pmd_is_valid_softleaf() 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 403e13009631..79f16b5aa5f0 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -486,11 +486,6 @@ 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)
@@ -693,10 +688,6 @@ 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 fff311830959..608d1011ce03 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 leaf_entry;
};

static void __init pte_basic_tests(struct pgtable_debug_args *args, int idx)
@@ -745,7 +746,7 @@ 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_leaf_soft_dirty_tests(struct pgtable_debug_args *args)
{
pmd_t pmd;

@@ -757,15 +758,16 @@ 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->leaf_entry);
+ WARN_ON(!pmd_is_huge(pmd));
+ WARN_ON(!pmd_is_valid_softleaf(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_leaf_soft_dirty_tests(struct pgtable_debug_args *args) { }
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

static void __init pte_swap_exclusive_tests(struct pgtable_debug_args *args)
@@ -818,7 +820,7 @@ 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_softleaf_tests(struct pgtable_debug_args *args)
{
swp_entry_t arch_entry;
pmd_t pmd1, pmd2;
@@ -827,15 +829,16 @@ 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->leaf_entry);
+ WARN_ON(!pmd_is_huge(pmd1));
+ WARN_ON(!pmd_is_valid_softleaf(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_softleaf_tests(struct pgtable_debug_args *args) { }
#endif /* CONFIG_ARCH_ENABLE_THP_MIGRATION */

static void __init swap_migration_tests(struct pgtable_debug_args *args)
@@ -1229,6 +1232,8 @@ 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->leaf_entry = make_writable_migration_entry(~0UL);

/*
* Allocate (huge) pages because some of the tests need to access
@@ -1318,12 +1323,12 @@ 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_leaf_soft_dirty_tests(&args);

pte_swap_exclusive_tests(&args);

pte_swap_tests(&args);
- pmd_swap_tests(&args);
+ pmd_softleaf_tests(&args);

swap_migration_tests(&args);

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 2f0bdc987596..d1a5c5f01d94 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1875,7 +1875,8 @@ 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() &&
+ pmd_is_valid_softleaf(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() && pmd_is_valid_softleaf(*pmd)) {
change_non_present_huge_pmd(mm, addr, pmd, uffd_wp,
uffd_wp_resolve);
goto unlock;
--
2.51.0