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mm/debug_vm_pgtable: use a swp_entry_t input value for swap tests

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The various __pte/pmd_to_swp_entry and __swp_entry_to_pte/pmd helper
functions are expected to operate on swap PTE/PMD entries, not on present
and mapped entries.

Reflect this in the swap tests by using a swp_entry_t as input value, and
convert it to a swap PTE/PMD for testing, similar to how it is already
done in pte_swap_exclusive_tests().  Move the swap entry creation from
there to init_args() and store it in args, so it can also be used in other
functions.

The pte/pmd_swap_tests() are also changed to compare entries instead of
pfn values, again similar to pte_swap_exclusive_tests().  pte/pmd_pfn()
helpers are also not expected to operate on swap PTE/PMD entries at all.

Also update documentation, to reflect that the helpers operate on swap
PTE/PMD entries and not present and mapped entries, and use correct names,
i.e.  __swp_to_pte/pmd_entry -> __swp_entry_to_pte/pmd.

For consistency, also change pte/pmd_swap_soft_dirty_tests() to use
args->swp_entry instead of a present and mapped PTE/PMD.

Link: https://lore.kernel.org/all/20250623184321.927418-1-gerald.schaefer@linux.ibm.com
Link: https://lkml.kernel.org/r/20250630164726.930405-1-gerald.schaefer@linux.ibm.com
Signed-off-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Gerald Schaefer 2025-06-30 18:47:25 +02:00 committed by Andrew Morton
parent 2a83529026
commit c26ad45ba5
2 changed files with 36 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
Documentation/mm/arch_pgtable_helpers.rst
View File

@ -236,13 +236,13 @@ SWAP Page Table Helpers
========================
+---------------------------+--------------------------------------------------+
| __pte_to_swp_entry | Creates a swapped entry (arch) from a mapped PTE |
| __pte_to_swp_entry | Creates a swp_entry_t (arch) from a swap PTE |
+---------------------------+--------------------------------------------------+
| __swp_to_pte_entry | Creates a mapped PTE from a swapped entry (arch) |
| __swp_entry_to_pte | Creates a swap PTE from a swp_entry_t (arch) |
+---------------------------+--------------------------------------------------+
| __pmd_to_swp_entry | Creates a swapped entry (arch) from a mapped PMD |
| __pmd_to_swp_entry | Creates a swp_entry_t (arch) from a swap PMD |
+---------------------------+--------------------------------------------------+
| __swp_to_pmd_entry | Creates a mapped PMD from a swapped entry (arch) |
| __swp_entry_to_pmd | Creates a swap PMD from a swp_entry_t (arch) |
+---------------------------+--------------------------------------------------+
| is_migration_entry | Tests a migration (read or write) swapped entry |
+-------------------------------+----------------------------------------------+

53
mm/debug_vm_pgtable.c
View File

@ -72,6 +72,8 @@ struct pgtable_debug_args {
unsigned long fixed_pud_pfn;
unsigned long fixed_pmd_pfn;
unsigned long fixed_pte_pfn;
swp_entry_t swp_entry;
};
static void __init pte_basic_tests(struct pgtable_debug_args *args, int idx)
@ -698,12 +700,15 @@ 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 = pfn_pte(args->fixed_pte_pfn, args->page_prot);
pte_t pte;
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));
WARN_ON(!pte_swp_soft_dirty(pte_swp_mksoft_dirty(pte)));
WARN_ON(pte_swp_soft_dirty(pte_swp_clear_soft_dirty(pte)));
}
@ -737,7 +742,9 @@ static void __init pmd_swap_soft_dirty_tests(struct pgtable_debug_args *args)
return;
pr_debug("Validating PMD swap soft dirty\n");
pmd = pfn_pmd(args->fixed_pmd_pfn, args->page_prot);
pmd = swp_entry_to_pmd(args->swp_entry);
WARN_ON(!is_swap_pmd(pmd));
WARN_ON(!pmd_swp_soft_dirty(pmd_swp_mksoft_dirty(pmd)));
WARN_ON(pmd_swp_soft_dirty(pmd_swp_clear_soft_dirty(pmd)));
}
@ -748,17 +755,11 @@ 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)
{
unsigned long max_swap_offset;
swp_entry_t entry, entry2;
pte_t pte;
pr_debug("Validating PTE swap exclusive\n");
/* 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 */
entry = swp_entry((1 << MAX_SWAPFILES_SHIFT) - 1, max_swap_offset);
entry = args->swp_entry;
pte = swp_entry_to_pte(entry);
WARN_ON(pte_swp_exclusive(pte));
@ -782,30 +783,34 @@ static void __init pte_swap_exclusive_tests(struct pgtable_debug_args *args)
static void __init pte_swap_tests(struct pgtable_debug_args *args)
{
swp_entry_t swp;
pte_t pte;
swp_entry_t arch_entry;
pte_t pte1, pte2;
pr_debug("Validating PTE swap\n");
pte = pfn_pte(args->fixed_pte_pfn, args->page_prot);
swp = __pte_to_swp_entry(pte);
pte = __swp_entry_to_pte(swp);
WARN_ON(args->fixed_pte_pfn != pte_pfn(pte));
pte1 = swp_entry_to_pte(args->swp_entry);
WARN_ON(!is_swap_pte(pte1));
arch_entry = __pte_to_swp_entry(pte1);
pte2 = __swp_entry_to_pte(arch_entry);
WARN_ON(memcmp(&pte1, &pte2, sizeof(pte1)));
}
#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
static void __init pmd_swap_tests(struct pgtable_debug_args *args)
{
swp_entry_t swp;
pmd_t pmd;
swp_entry_t arch_entry;
pmd_t pmd1, pmd2;
if (!has_transparent_hugepage())
return;
pr_debug("Validating PMD swap\n");
pmd = pfn_pmd(args->fixed_pmd_pfn, args->page_prot);
swp = __pmd_to_swp_entry(pmd);
pmd = __swp_entry_to_pmd(swp);
WARN_ON(args->fixed_pmd_pfn != pmd_pfn(pmd));
pmd1 = swp_entry_to_pmd(args->swp_entry);
WARN_ON(!is_swap_pmd(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) { }
@ -1110,6 +1115,7 @@ static void __init init_fixed_pfns(struct pgtable_debug_args *args)
static int __init init_args(struct pgtable_debug_args *args)
{
unsigned long max_swap_offset;
struct page *page = NULL;
int ret = 0;
@ -1192,6 +1198,11 @@ static int __init init_args(struct pgtable_debug_args *args)
init_fixed_pfns(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);
/*
* Allocate (huge) pages because some of the tests need to access
* the data in the pages. The corresponding tests will be skipped