[PATCH v3 05/16] mm: use leaf entries in debug pgtable + remove is_swap_pte()

Lorenzo Stoakes
2025-11-10T22:23:18Z

Remove invocations of is_swap_pte() in mm/debug_vm_pgtable.c and use
softleaf_from_pte() and softleaf_is_swap() as necessary to replace this
usage.

We update the test code to use a 'true' swap entry throughout so we are
guaranteed this is not a non-swap entry, so all asserts continue to operate
correctly.

With this change in place, we no longer use is_swap_pte() anywhere, so
remove it.

Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
---
include/linux/swapops.h | 6 ------
mm/debug_vm_pgtable.c | 39 ++++++++++++++++++++++++---------------
2 files changed, 24 insertions(+), 21 deletions(-)

diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index 0a4b3f51ecf5..a66ac4f2105c 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -120,12 +120,6 @@ static inline unsigned long swp_offset_pfn(swp_entry_t entry)
return swp_offset(entry) & SWP_PFN_MASK;
}

-/* check whether a pte points to a swap entry */
-static inline int is_swap_pte(pte_t pte)
-{
- return !pte_none(pte) && !pte_present(pte);
-}
-
/*
* Convert the arch-dependent pte representation of a swp_entry_t into an
* arch-independent swp_entry_t.
diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index 055e0e025b42..fff311830959 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -25,7 +25,7 @@
#include <linux/random.h>
#include <linux/spinlock.h>
#include <linux/swap.h>
-#include <linux/swapops.h>
+#include <linux/leafops.h>
#include <linux/start_kernel.h>
#include <linux/sched/mm.h>
#include <linux/io.h>
@@ -714,14 +714,16 @@ static void __init pte_soft_dirty_tests(struct pgtable_debug_args *args)
static void __init pte_swap_soft_dirty_tests(struct pgtable_debug_args *args)
{
pte_t pte;
+ softleaf_t entry;

if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY))
return;

pr_debug("Validating PTE swap soft dirty\n");
pte = swp_entry_to_pte(args->swp_entry);
- WARN_ON(!is_swap_pte(pte));
+ entry = softleaf_from_pte(pte);

+ WARN_ON(!softleaf_is_swap(entry));
WARN_ON(!pte_swp_soft_dirty(pte_swp_mksoft_dirty(pte)));
WARN_ON(pte_swp_soft_dirty(pte_swp_clear_soft_dirty(pte)));
}
@@ -768,40 +770,47 @@ static void __init pmd_swap_soft_dirty_tests(struct pgtable_debug_args *args) {

static void __init pte_swap_exclusive_tests(struct pgtable_debug_args *args)
{
- swp_entry_t entry, entry2;
+ swp_entry_t entry;
+ softleaf_t softleaf;
pte_t pte;

pr_debug("Validating PTE swap exclusive\n");
entry = args->swp_entry;

pte = swp_entry_to_pte(entry);
+ softleaf = softleaf_from_pte(pte);
+
WARN_ON(pte_swp_exclusive(pte));
- WARN_ON(!is_swap_pte(pte));
- entry2 = pte_to_swp_entry(pte);
- WARN_ON(memcmp(&entry, &entry2, sizeof(entry)));
+ WARN_ON(!softleaf_is_swap(softleaf));
+ WARN_ON(memcmp(&entry, &softleaf, sizeof(entry)));

pte = pte_swp_mkexclusive(pte);
+ softleaf = softleaf_from_pte(pte);
+
WARN_ON(!pte_swp_exclusive(pte));
- WARN_ON(!is_swap_pte(pte));
+ WARN_ON(!softleaf_is_swap(softleaf));
WARN_ON(pte_swp_soft_dirty(pte));
- entry2 = pte_to_swp_entry(pte);
- WARN_ON(memcmp(&entry, &entry2, sizeof(entry)));
+ WARN_ON(memcmp(&entry, &softleaf, sizeof(entry)));

pte = pte_swp_clear_exclusive(pte);
+ softleaf = softleaf_from_pte(pte);
+
WARN_ON(pte_swp_exclusive(pte));
- WARN_ON(!is_swap_pte(pte));
- entry2 = pte_to_swp_entry(pte);
- WARN_ON(memcmp(&entry, &entry2, sizeof(entry)));
+ WARN_ON(!softleaf_is_swap(softleaf));
+ WARN_ON(memcmp(&entry, &softleaf, sizeof(entry)));
}

static void __init pte_swap_tests(struct pgtable_debug_args *args)
{
swp_entry_t arch_entry;
+ softleaf_t entry;
pte_t pte1, pte2;

pr_debug("Validating PTE swap\n");
pte1 = swp_entry_to_pte(args->swp_entry);
- WARN_ON(!is_swap_pte(pte1));
+ entry = softleaf_from_pte(pte1);
+
+ WARN_ON(!softleaf_is_swap(entry));

arch_entry = __pte_to_swp_entry(pte1);
pte2 = __swp_entry_to_pte(arch_entry);
@@ -1218,8 +1227,8 @@ static int __init init_args(struct pgtable_debug_args *args)

/* See generic_max_swapfile_size(): probe the maximum offset */
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 */
- args->swp_entry = swp_entry((1 << MAX_SWAPFILES_SHIFT) - 1, max_swap_offset);
+ /* Create a swp entry with all possible bits set while still being swap. */
+ args->swp_entry = swp_entry(MAX_SWAPFILES - 1, max_swap_offset);

/*
* Allocate (huge) pages because some of the tests need to access
--
2.51.0