There are probably ways to have an even cleaner interface (e.g.,
pass the mapping granularity instead of "compound"). For now, let's
handle it like folio_add_file_rmap_range().
Use separate loops for handling the "SetPageAnonExclusive()" case and
performing debug checks. The latter should get optimized out automatically
without CONFIG_DEBUG_VM.
We'll use this function to batch rmap operations when PTE-remapping a
PMD-mapped THP next.
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
include/linux/rmap.h | 3 ++
mm/rmap.c | 69 +++++++++++++++++++++++++++++++++-----------
2 files changed, 55 insertions(+), 17 deletions(-)
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 39aeab457f4a..76e6fb1dad5c 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -393,6 +393,9 @@ typedef int __bitwise rmap_t;
* rmap interfaces called when adding or removing pte of page
*/
void folio_move_anon_rmap(struct folio *, struct vm_area_struct *);
+void folio_add_anon_rmap_range(struct folio *, struct page *,
+ unsigned int nr_pages, struct vm_area_struct *,
+ unsigned long address, rmap_t flags);
void page_add_anon_rmap(struct page *, struct vm_area_struct *,
unsigned long address, rmap_t flags);
void page_add_new_anon_rmap(struct page *, struct vm_area_struct *,
diff --git a/mm/rmap.c b/mm/rmap.c
index 689ad85cf87e..da7fa46a18fc 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1240,25 +1240,29 @@ static void __page_check_anon_rmap(struct folio *folio, struct page *page,
}
/**
- * page_add_anon_rmap - add pte mapping to an anonymous page
- * @page: the page to add the mapping to
- * @vma: the vm area in which the mapping is added
- * @address: the user virtual address mapped
- * @flags: the rmap flags
+ * folio_add_anon_rmap_range - add mappings to a page range of an anon folio
+ * @folio: The folio to add the mapping to
+ * @page: The first page to add
+ * @nr_pages: The number of pages which will be mapped
+ * @vma: The vm area in which the mapping is added
+ * @address: The user virtual address of the first page to map
+ * @flags: The rmap flags
+ *
+ * The page range of folio is defined by [first_page, first_page + nr_pages)
*
* The caller needs to hold the pte lock, and the page must be locked in
* the anon_vma case: to serialize mapping,index checking after setting,
- * and to ensure that PageAnon is not being upgraded racily to PageKsm
- * (but PageKsm is never downgraded to PageAnon).
+ * and to ensure that an anon folio is not being upgraded racily to a KSM folio
+ * (but KSM folios are never downgraded).
*/
-void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma,
+void folio_add_anon_rmap_range(struct folio *folio, struct page *page,
+ unsigned int nr_pages, struct vm_area_struct *vma,
unsigned long address, rmap_t flags)
{
- struct folio *folio = page_folio(page);
- unsigned int nr, nr_pmdmapped = 0;
+ unsigned int i, nr, nr_pmdmapped = 0;
bool compound = flags & RMAP_COMPOUND;
- nr = __folio_add_rmap_range(folio, page, 1, vma, compound,
+ nr = __folio_add_rmap_range(folio, page, nr_pages, vma, compound,
&nr_pmdmapped);
if (nr_pmdmapped)
__lruvec_stat_mod_folio(folio, NR_ANON_THPS, nr_pmdmapped);
@@ -1279,12 +1283,20 @@ void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma,
} else if (likely(!folio_test_ksm(folio))) {
__page_check_anon_rmap(folio, page, vma, address);
}
- if (flags & RMAP_EXCLUSIVE)
- SetPageAnonExclusive(page);
- /* While PTE-mapping a THP we have a PMD and a PTE mapping. */
- VM_WARN_ON_FOLIO((atomic_read(&page->_mapcount) > 0 ||
- (folio_test_large(folio) && folio_entire_mapcount(folio) > 1)) &&
- PageAnonExclusive(page), folio);
+
+ if (flags & RMAP_EXCLUSIVE) {
+ for (i = 0; i < nr_pages; i++)
+ SetPageAnonExclusive(page + i);
+ }
+ for (i = 0; i < nr_pages; i++) {
+ struct page *cur_page = page + i;
+
+ /* While PTE-mapping a THP we have a PMD and a PTE mapping. */
+ VM_WARN_ON_FOLIO((atomic_read(&cur_page->_mapcount) > 0 ||
+ (folio_test_large(folio) &&
+ folio_entire_mapcount(folio) > 1)) &&
+ PageAnonExclusive(cur_page), folio);
+ }
/*
* For large folio, only mlock it if it's fully mapped to VMA. It's
@@ -1296,6 +1308,29 @@ void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma,
mlock_vma_folio(folio, vma);
}
+/**
+ * page_add_anon_rmap - add mappings to an anonymous page
+ * @page: The page to add the mapping to
+ * @vma: The vm area in which the mapping is added
+ * @address: The user virtual address of the page to map
+ * @flags: The rmap flags
+ *
+ * See folio_add_anon_rmap_range().
+ */
+void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma,
+ unsigned long address, rmap_t flags)
+{
+ struct folio *folio = page_folio(page);
+ unsigned int nr_pages;
+
+ if (likely(!(flags & RMAP_COMPOUND)))
+ nr_pages = 1;
+ else
+ nr_pages = folio_nr_pages(folio);
+
+ folio_add_anon_rmap_range(folio, page, nr_pages, vma, address, flags);
+}
+
/**
* folio_add_new_anon_rmap - Add mapping to a new anonymous folio.
* @folio: The folio to add the mapping to.
--
2.41.0
