[PATCH v1 3/8] mm: Add helpers to create migration entries from struct pages
From: Jordan Niethe <hidden>
Date: 2025-12-31 04:32:34
Also in:
dri-devel, intel-xe, linux-mm, lkml
Subsystem:
memory management, memory management - memory policy and migration, memory management - rmap (reverse mapping), memory management - swap, memory management - thp (transparent huge page), the rest · Maintainers:
Andrew Morton, David Hildenbrand, Lorenzo Stoakes, Chris Li, Kairui Song, Linus Torvalds
To create a new migration entry for a given struct page, that page is first converted to its pfn, before passing the pfn to make_readable_migration_entry() (and friends). A future change will remove device private pages from the physical address space. This will mean that device private pages no longer have a pfn and must be handled separately. Prepare for this with a new set of helpers: - make_readable_migration_entry_from_page() - make_readable_exclusive_migration_entry_from_page() - make_writable_migration_entry_from_page() These helpers take a struct page as parameter instead of a pfn. This will allow more flexibility for handling the swap offset field differently for device private pages. Signed-off-by: Jordan Niethe <redacted> --- v1: - New to series --- include/linux/swapops.h | 25 +++++++++++++++++++++++++ mm/huge_memory.c | 18 +++++++++--------- mm/migrate_device.c | 12 ++++++------ mm/rmap.c | 12 ++++++------ 4 files changed, 46 insertions(+), 21 deletions(-)
diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index 8cfc966eae48..72aa636fdb48 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h@@ -173,16 +173,31 @@ static inline swp_entry_t make_readable_migration_entry(pgoff_t offset) return swp_entry(SWP_MIGRATION_READ, offset); } +static inline swp_entry_t make_readable_migration_entry_from_page(struct page *page) +{ + return swp_entry(SWP_MIGRATION_READ, page_to_pfn(page)); +} + static inline swp_entry_t make_readable_exclusive_migration_entry(pgoff_t offset) { return swp_entry(SWP_MIGRATION_READ_EXCLUSIVE, offset); } +static inline swp_entry_t make_readable_exclusive_migration_entry_from_page(struct page *page) +{ + return swp_entry(SWP_MIGRATION_READ_EXCLUSIVE, page_to_pfn(page)); +} + static inline swp_entry_t make_writable_migration_entry(pgoff_t offset) { return swp_entry(SWP_MIGRATION_WRITE, offset); } +static inline swp_entry_t make_writable_migration_entry_from_page(struct page *page) +{ + return swp_entry(SWP_MIGRATION_WRITE, page_to_pfn(page)); +} + /* * Returns whether the host has large enough swap offset field to support * carrying over pgtable A/D bits for page migrations. The result is
@@ -222,11 +237,21 @@ static inline swp_entry_t make_readable_migration_entry(pgoff_t offset) return swp_entry(0, 0); } +static inline swp_entry_t make_readable_migration_entry_from_page(struct page *page) +{ + return swp_entry(0, 0); +} + static inline swp_entry_t make_readable_exclusive_migration_entry(pgoff_t offset) { return swp_entry(0, 0); } +static inline swp_entry_t make_readable_exclusive_migration_entry_from_page(struct page *page) +{ + return swp_entry(0, 0); +} + static inline swp_entry_t make_writable_migration_entry(pgoff_t offset) { return swp_entry(0, 0);
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 40cf59301c21..08c68e2e3f06 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c@@ -3183,14 +3183,14 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, for (i = 0, addr = haddr; i < HPAGE_PMD_NR; i++, addr += PAGE_SIZE) { if (write) - swp_entry = make_writable_migration_entry( - page_to_pfn(page + i)); + swp_entry = make_writable_migration_entry_from_page( + page + i); else if (anon_exclusive) - swp_entry = make_readable_exclusive_migration_entry( - page_to_pfn(page + i)); + swp_entry = make_readable_exclusive_migration_entry_from_page( + page + i); else - swp_entry = make_readable_migration_entry( - page_to_pfn(page + i)); + swp_entry = make_readable_migration_entry_from_page( + page + i); if (young) swp_entry = make_migration_entry_young(swp_entry); if (dirty)
@@ -4890,11 +4890,11 @@ int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw, if (pmd_dirty(pmdval)) folio_mark_dirty(folio); if (pmd_write(pmdval)) - entry = make_writable_migration_entry(page_to_pfn(page)); + entry = make_writable_migration_entry_from_page(page); else if (anon_exclusive) - entry = make_readable_exclusive_migration_entry(page_to_pfn(page)); + entry = make_readable_exclusive_migration_entry_from_page(page); else - entry = make_readable_migration_entry(page_to_pfn(page)); + entry = make_readable_migration_entry_from_page(page); if (pmd_young(pmdval)) entry = make_migration_entry_young(entry); if (pmd_dirty(pmdval))
diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index 5d108ddf1a97..7eef21d63364 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c@@ -438,14 +438,14 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp, /* Setup special migration page table entry */ if (mpfn & MIGRATE_PFN_WRITE) - entry = make_writable_migration_entry( - page_to_pfn(page)); + entry = make_writable_migration_entry_from_page( + page); else if (anon_exclusive) - entry = make_readable_exclusive_migration_entry( - page_to_pfn(page)); + entry = make_readable_exclusive_migration_entry_from_page( + page); else - entry = make_readable_migration_entry( - page_to_pfn(page)); + entry = make_readable_migration_entry_from_page( + page); if (pte_present(pte)) { if (pte_young(pte)) entry = make_migration_entry_young(entry);
diff --git a/mm/rmap.c b/mm/rmap.c
index 79a2478b4aa9..bb881b0c4b06 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c@@ -2539,14 +2539,14 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, * pte is removed and then restart fault handling. */ if (writable) - entry = make_writable_migration_entry( - page_to_pfn(subpage)); + entry = make_writable_migration_entry_from_page( + subpage); else if (anon_exclusive) - entry = make_readable_exclusive_migration_entry( - page_to_pfn(subpage)); + entry = make_readable_exclusive_migration_entry_from_page( + subpage); else - entry = make_readable_migration_entry( - page_to_pfn(subpage)); + entry = make_readable_migration_entry_from_page( + subpage); if (likely(pte_present(pteval))) { if (pte_young(pteval)) entry = make_migration_entry_young(entry);
--
2.34.1