[PATCH v2 08/11] mm: Add helpers to create device private entries from struct pages
From: Jordan Niethe <hidden>
Date: 2026-01-07 09:19:05
Also in:
dri-devel, intel-xe, linux-mm, lkml
Subsystem:
memory management, memory management - memory policy and migration, memory management - swap, memory management - thp (transparent huge page), the rest · Maintainers:
Andrew Morton, David Hildenbrand, Chris Li, Kairui Song, Lorenzo Stoakes, Linus Torvalds
To create a new device private entry for a given struct page, that page is first converted to its pfn, before passing the pfn to make_writable_device_private_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_device_private_entry_from_page() - make_writable_device_private_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 v2: - Add flag param --- include/linux/swapops.h | 24 ++++++++++++++++++++++++ mm/huge_memory.c | 14 ++++++-------- mm/migrate.c | 6 ++---- mm/migrate_device.c | 12 ++++-------- 4 files changed, 36 insertions(+), 20 deletions(-)
diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index bae76d3831fb..f7d85a451a2b 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h@@ -138,11 +138,23 @@ static inline swp_entry_t make_readable_device_private_entry(pgoff_t offset) return swp_entry(SWP_DEVICE_READ, offset); } +static inline swp_entry_t make_readable_device_private_entry_from_page(struct page *page, + pgoff_t flags) +{ + return swp_entry(SWP_DEVICE_READ, page_to_pfn(page) | flags); +} + static inline swp_entry_t make_writable_device_private_entry(pgoff_t offset) { return swp_entry(SWP_DEVICE_WRITE, offset); } +static inline swp_entry_t make_writable_device_private_entry_from_page(struct page *page, + pgoff_t flags) +{ + return swp_entry(SWP_DEVICE_WRITE, page_to_pfn(page) | flags); +} + static inline swp_entry_t make_device_exclusive_entry(pgoff_t offset) { return swp_entry(SWP_DEVICE_EXCLUSIVE, offset);
@@ -191,11 +203,23 @@ static inline swp_entry_t make_readable_device_private_entry(pgoff_t offset) return swp_entry(0, 0); } +static inline swp_entry_t make_readable_device_private_entry_from_page(struct page *page, + pgoff_t flags) +{ + return swp_entry(0, 0); +} + static inline swp_entry_t make_writable_device_private_entry(pgoff_t offset) { return swp_entry(0, 0); } +static inline swp_entry_t make_writable_device_private_entry_from_page(struct page *page, + pgoff_t flags) +{ + return swp_entry(0, 0); +} + static inline swp_entry_t make_device_exclusive_entry(pgoff_t offset) { return swp_entry(0, 0);
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index e3a448cdb34d..03f1f13bb24c 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c@@ -3219,11 +3219,11 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, * is false. */ if (write) - swp_entry = make_writable_device_private_entry( - page_to_pfn(page + i)); + swp_entry = make_writable_device_private_entry_from_page( + page + i, 0); else - swp_entry = make_readable_device_private_entry( - page_to_pfn(page + i)); + swp_entry = make_readable_device_private_entry_from_page( + page + i, 0); /* * Young and dirty bits are not progated via swp_entry */
@@ -4950,11 +4950,9 @@ void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new) swp_entry_t entry; if (pmd_write(pmde)) - entry = make_writable_device_private_entry( - page_to_pfn(new)); + entry = make_writable_device_private_entry_from_page(new, 0); else - entry = make_readable_device_private_entry( - page_to_pfn(new)); + entry = make_readable_device_private_entry_from_page(new, 0); pmde = swp_entry_to_pmd(entry); if (pmd_swp_soft_dirty(*pvmw->pmd))
diff --git a/mm/migrate.c b/mm/migrate.c
index 5169f9717f60..6cc6c989ab6b 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c@@ -399,11 +399,9 @@ static bool remove_migration_pte(struct folio *folio, if (unlikely(is_device_private_page(new))) { if (pte_write(pte)) - entry = make_writable_device_private_entry( - page_to_pfn(new)); + entry = make_writable_device_private_entry_from_page(new, 0); else - entry = make_readable_device_private_entry( - page_to_pfn(new)); + entry = make_readable_device_private_entry_from_page(new, 0); pte = softleaf_to_pte(entry); if (pte_swp_soft_dirty(old_pte)) pte = pte_swp_mksoft_dirty(pte);
diff --git a/mm/migrate_device.c b/mm/migrate_device.c
index c876526ac6a3..0ca6f78df0e2 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c@@ -836,11 +836,9 @@ static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate, swp_entry_t swp_entry; if (vma->vm_flags & VM_WRITE) - swp_entry = make_writable_device_private_entry( - page_to_pfn(page)); + swp_entry = make_writable_device_private_entry_from_page(page, 0); else - swp_entry = make_readable_device_private_entry( - page_to_pfn(page)); + swp_entry = make_readable_device_private_entry_from_page(page, 0); entry = swp_entry_to_pmd(swp_entry); } else { if (folio_is_zone_device(folio) &&
@@ -1033,11 +1031,9 @@ static void migrate_vma_insert_page(struct migrate_vma *migrate, swp_entry_t swp_entry; if (vma->vm_flags & VM_WRITE) - swp_entry = make_writable_device_private_entry( - page_to_pfn(page)); + swp_entry = make_writable_device_private_entry_from_page(page, 0); else - swp_entry = make_readable_device_private_entry( - page_to_pfn(page)); + swp_entry = make_readable_device_private_entry_from_page(page, 0); entry = swp_entry_to_pte(swp_entry); } else { if (folio_is_zone_device(folio) &&
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