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Message-Id: <20251231043154.42931-6-jniethe@nvidia.com>
Date: Wed, 31 Dec 2025 15:31:51 +1100
From: Jordan Niethe <jniethe@...dia.com>
To: linux-mm@...ck.org
Cc: balbirs@...dia.com,
matthew.brost@...el.com,
akpm@...ux-foundation.org,
linux-kernel@...r.kernel.org,
dri-devel@...ts.freedesktop.org,
david@...hat.com,
ziy@...dia.com,
apopple@...dia.com,
lorenzo.stoakes@...cle.com,
lyude@...hat.com,
dakr@...nel.org,
airlied@...il.com,
simona@...ll.ch,
rcampbell@...dia.com,
mpenttil@...hat.com,
jgg@...dia.com,
willy@...radead.org,
linuxppc-dev@...ts.ozlabs.org,
intel-xe@...ts.freedesktop.org,
jgg@...pe.ca,
Felix.Kuehling@....com
Subject: [PATCH v1 5/8] mm: Add helpers to create device private entries from struct pages
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 <jniethe@...dia.com>
---
v1:
- New to series
---
include/linux/swapops.h | 20 ++++++++++++++++++++
mm/huge_memory.c | 14 ++++++--------
mm/memory.c | 4 ++--
mm/migrate.c | 6 ++----
mm/migrate_device.c | 12 ++++--------
5 files changed, 34 insertions(+), 22 deletions(-)
diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index 2bd01f97b4f0..ddf2763d69e9 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -138,11 +138,21 @@ 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)
+{
+ return swp_entry(SWP_DEVICE_READ, page_to_pfn(page));
+}
+
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)
+{
+ return swp_entry(SWP_DEVICE_WRITE, page_to_pfn(page));
+}
+
static inline swp_entry_t make_device_exclusive_entry(pgoff_t offset)
{
return swp_entry(SWP_DEVICE_EXCLUSIVE, offset);
@@ -191,11 +201,21 @@ 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)
+{
+ 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)
+{
+ 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 bbfe5e87884a..31ea473cbcbd 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3225,11 +3225,11 @@ 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);
else
- swp_entry = make_readable_device_private_entry(
- page_to_pfn(page + i));
+ swp_entry = make_readable_device_private_entry_from_page(
+ page + i);
/*
* Young and dirty bits are not progated via swp_entry
*/
@@ -4956,11 +4956,9 @@ 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);
else
- entry = make_readable_device_private_entry(
- page_to_pfn(new));
+ entry = make_readable_device_private_entry_from_page(new);
pmde = swp_entry_to_pmd(entry);
if (pmd_swp_soft_dirty(*pvmw->pmd))
diff --git a/mm/memory.c b/mm/memory.c
index 8e5e305bc2dc..076d7acb7267 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1005,8 +1005,8 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
*/
if (softleaf_is_device_private_write(entry) &&
is_cow_mapping(vm_flags)) {
- entry = make_readable_device_private_entry(
- swp_offset(entry));
+ entry = make_readable_device_private_entry
+ (swp_offset(entry));
pte = swp_entry_to_pte(entry);
if (pte_swp_uffd_wp(orig_pte))
pte = pte_swp_mkuffd_wp(pte);
diff --git a/mm/migrate.c b/mm/migrate.c
index 5169f9717f60..9ec9bcd37882 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);
else
- entry = make_readable_device_private_entry(
- page_to_pfn(new));
+ entry = make_readable_device_private_entry_from_page(new);
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 7eef21d63364..5cc58a5876a0 100644
--- a/mm/migrate_device.c
+++ b/mm/migrate_device.c
@@ -842,11 +842,9 @@ 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);
else
- swp_entry = make_readable_device_private_entry(
- page_to_pfn(page));
+ swp_entry = make_readable_device_private_entry_from_page(page);
entry = swp_entry_to_pmd(swp_entry);
} else {
if (folio_is_zone_device(folio) &&
@@ -1039,11 +1037,9 @@ 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);
else
- swp_entry = make_readable_device_private_entry(
- page_to_pfn(page));
+ swp_entry = make_readable_device_private_entry_from_page(page);
entry = swp_entry_to_pte(swp_entry);
} else {
if (folio_is_zone_device(folio) &&
--
2.34.1
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