[PATCH v3 07/20] mm/rmap: pass dst_vma to folio_dup_file_rmap_pte() and friends

David Hildenbrand
2025-03-03T16:30:45Z

We'll need access to the destination MM when modifying the large mapcount
of a non-hugetlb large folios next. So pass in the destination VMA.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
include/linux/rmap.h | 42 +++++++++++++++++++++++++-----------------
mm/huge_memory.c | 2 +-
mm/memory.c | 10 +++++-----
3 files changed, 31 insertions(+), 23 deletions(-)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 6abf7960077aa..e795610bade80 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -335,7 +335,8 @@ static inline void hugetlb_remove_rmap(struct folio *folio)
}

static __always_inline void __folio_dup_file_rmap(struct folio *folio,
- struct page *page, int nr_pages, enum rmap_level level)
+ struct page *page, int nr_pages, struct vm_area_struct *dst_vma,
+ enum rmap_level level)
{
const int orig_nr_pages = nr_pages;

@@ -366,45 +367,47 @@ static __always_inline void __folio_dup_file_rmap(struct folio *folio,
* @folio: The folio to duplicate the mappings of
* @page: The first page to duplicate the mappings of
* @nr_pages: The number of pages of which the mapping will be duplicated
+ * @dst_vma: The destination vm area
*
* The page range of the folio is defined by [page, page + nr_pages)
*
* The caller needs to hold the page table lock.
*/
static inline void folio_dup_file_rmap_ptes(struct folio *folio,
- struct page *page, int nr_pages)
+ struct page *page, int nr_pages, struct vm_area_struct *dst_vma)
{
- __folio_dup_file_rmap(folio, page, nr_pages, RMAP_LEVEL_PTE);
+ __folio_dup_file_rmap(folio, page, nr_pages, dst_vma, RMAP_LEVEL_PTE);
}

static __always_inline void folio_dup_file_rmap_pte(struct folio *folio,
- struct page *page)
+ struct page *page, struct vm_area_struct *dst_vma)
{
- __folio_dup_file_rmap(folio, page, 1, RMAP_LEVEL_PTE);
+ __folio_dup_file_rmap(folio, page, 1, dst_vma, RMAP_LEVEL_PTE);
}

/**
* folio_dup_file_rmap_pmd - duplicate a PMD mapping of a page range of a folio
* @folio: The folio to duplicate the mapping of
* @page: The first page to duplicate the mapping of
+ * @dst_vma: The destination vm area
*
* The page range of the folio is defined by [page, page + HPAGE_PMD_NR)
*
* The caller needs to hold the page table lock.
*/
static inline void folio_dup_file_rmap_pmd(struct folio *folio,
- struct page *page)
+ struct page *page, struct vm_area_struct *dst_vma)
{
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
- __folio_dup_file_rmap(folio, page, HPAGE_PMD_NR, RMAP_LEVEL_PTE);
+ __folio_dup_file_rmap(folio, page, HPAGE_PMD_NR, dst_vma, RMAP_LEVEL_PTE);
#else
WARN_ON_ONCE(true);
#endif
}

static __always_inline int __folio_try_dup_anon_rmap(struct folio *folio,
- struct page *page, int nr_pages, struct vm_area_struct *src_vma,
- enum rmap_level level)
+ struct page *page, int nr_pages, struct vm_area_struct *dst_vma,
+ struct vm_area_struct *src_vma, enum rmap_level level)
{
const int orig_nr_pages = nr_pages;
bool maybe_pinned;
@@ -470,6 +473,7 @@ static __always_inline int __folio_try_dup_anon_rmap(struct folio *folio,
* @folio: The folio to duplicate the mappings of
* @page: The first page to duplicate the mappings of
* @nr_pages: The number of pages of which the mapping will be duplicated
+ * @dst_vma: The destination vm area
* @src_vma: The vm area from which the mappings are duplicated
*
* The page range of the folio is defined by [page, page + nr_pages)
@@ -488,16 +492,18 @@ static __always_inline int __folio_try_dup_anon_rmap(struct folio *folio,
* Returns 0 if duplicating the mappings succeeded. Returns -EBUSY otherwise.
*/
static inline int folio_try_dup_anon_rmap_ptes(struct folio *folio,
- struct page *page, int nr_pages, struct vm_area_struct *src_vma)
+ struct page *page, int nr_pages, struct vm_area_struct *dst_vma,
+ struct vm_area_struct *src_vma)
{
- return __folio_try_dup_anon_rmap(folio, page, nr_pages, src_vma,
- RMAP_LEVEL_PTE);
+ return __folio_try_dup_anon_rmap(folio, page, nr_pages, dst_vma,
+ src_vma, RMAP_LEVEL_PTE);
}

static __always_inline int folio_try_dup_anon_rmap_pte(struct folio *folio,
- struct page *page, struct vm_area_struct *src_vma)
+ struct page *page, struct vm_area_struct *dst_vma,
+ struct vm_area_struct *src_vma)
{
- return __folio_try_dup_anon_rmap(folio, page, 1, src_vma,
+ return __folio_try_dup_anon_rmap(folio, page, 1, dst_vma, src_vma,
RMAP_LEVEL_PTE);
}

@@ -506,6 +512,7 @@ static __always_inline int folio_try_dup_anon_rmap_pte(struct folio *folio,
* of a folio
* @folio: The folio to duplicate the mapping of
* @page: The first page to duplicate the mapping of
+ * @dst_vma: The destination vm area
* @src_vma: The vm area from which the mapping is duplicated
*
* The page range of the folio is defined by [page, page + HPAGE_PMD_NR)
@@ -524,11 +531,12 @@ static __always_inline int folio_try_dup_anon_rmap_pte(struct folio *folio,
* Returns 0 if duplicating the mapping succeeded. Returns -EBUSY otherwise.
*/
static inline int folio_try_dup_anon_rmap_pmd(struct folio *folio,
- struct page *page, struct vm_area_struct *src_vma)
+ struct page *page, struct vm_area_struct *dst_vma,
+ struct vm_area_struct *src_vma)
{
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
- return __folio_try_dup_anon_rmap(folio, page, HPAGE_PMD_NR, src_vma,
- RMAP_LEVEL_PMD);
+ return __folio_try_dup_anon_rmap(folio, page, HPAGE_PMD_NR, dst_vma,
+ src_vma, RMAP_LEVEL_PMD);
#else
WARN_ON_ONCE(true);
return -EBUSY;
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 07d43ca6db1c6..8e8b07e8b12fe 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1782,7 +1782,7 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
src_folio = page_folio(src_page);

folio_get(src_folio);
- if (unlikely(folio_try_dup_anon_rmap_pmd(src_folio, src_page, src_vma))) {
+ if (unlikely(folio_try_dup_anon_rmap_pmd(src_folio, src_page, dst_vma, src_vma))) {
/* Page maybe pinned: split and retry the fault on PTEs. */
folio_put(src_folio);
pte_free(dst_mm, pgtable);
diff --git a/mm/memory.c b/mm/memory.c
index 1efc393e32b6d..73b783c7d7d51 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -866,7 +866,7 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
folio_get(folio);
rss[mm_counter(folio)]++;
/* Cannot fail as these pages cannot get pinned. */
- folio_try_dup_anon_rmap_pte(folio, page, src_vma);
+ folio_try_dup_anon_rmap_pte(folio, page, dst_vma, src_vma);

/*
* We do not preserve soft-dirty information, because so
@@ -1020,14 +1020,14 @@ copy_present_ptes(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma
folio_ref_add(folio, nr);
if (folio_test_anon(folio)) {
if (unlikely(folio_try_dup_anon_rmap_ptes(folio, page,
- nr, src_vma))) {
+ nr, dst_vma, src_vma))) {
folio_ref_sub(folio, nr);
return -EAGAIN;
}
rss[MM_ANONPAGES] += nr;
VM_WARN_ON_FOLIO(PageAnonExclusive(page), folio);
} else {
- folio_dup_file_rmap_ptes(folio, page, nr);
+ folio_dup_file_rmap_ptes(folio, page, nr, dst_vma);
rss[mm_counter_file(folio)] += nr;
}
if (any_writable)
@@ -1045,7 +1045,7 @@ copy_present_ptes(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma
* guarantee the pinned page won't be randomly replaced in the
* future.
*/
- if (unlikely(folio_try_dup_anon_rmap_pte(folio, page, src_vma))) {
+ if (unlikely(folio_try_dup_anon_rmap_pte(folio, page, dst_vma, src_vma))) {
/* Page may be pinned, we have to copy. */
folio_put(folio);
err = copy_present_page(dst_vma, src_vma, dst_pte, src_pte,
@@ -1055,7 +1055,7 @@ copy_present_ptes(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma
rss[MM_ANONPAGES]++;
VM_WARN_ON_FOLIO(PageAnonExclusive(page), folio);
} else {
- folio_dup_file_rmap_pte(folio, page);
+ folio_dup_file_rmap_pte(folio, page, dst_vma);
rss[mm_counter_file(folio)]++;
}

--
2.48.1