hugetlb rmap handling differs quite a lot from "ordinary" rmap code. We
don't want this hugetlb special-casing in the rmap functions, as
we're special casing the callers already. Let's simply use a separate
function for hugetlb.
Let's introduce and use hugetlb_remove_rmap() and remove the hugetlb
code from page_remove_rmap(). This effectively removes one check on the
small-folio path as well.
While this is a cleanup, this will also make it easier to change rmap
handling for partially-mappable folios.
Note: all possible candidates that need care are page_remove_rmap() that
pass compound=true.
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
include/linux/rmap.h | 5 +++++
mm/hugetlb.c | 4 ++--
mm/rmap.c | 17 ++++++++---------
3 files changed, 15 insertions(+), 11 deletions(-)
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 4c5bfeb05463..e8d1dc1d5361 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -208,6 +208,11 @@ void hugetlb_add_anon_rmap(struct folio *, struct vm_area_struct *,
void hugetlb_add_new_anon_rmap(struct folio *, struct vm_area_struct *,
unsigned long address);
+static inline void hugetlb_remove_rmap(struct folio *folio)
+{
+ atomic_dec(&folio->_entire_mapcount);
+}
+
static inline void __page_dup_rmap(struct page *page, bool compound)
{
if (compound) {
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 4cfa0679661e..d17bb53b19ff 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5669,7 +5669,7 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
make_pte_marker(PTE_MARKER_UFFD_WP),
sz);
hugetlb_count_sub(pages_per_huge_page(h), mm);
- page_remove_rmap(page, vma, true);
+ hugetlb_remove_rmap(page_folio(page));
spin_unlock(ptl);
tlb_remove_page_size(tlb, page, huge_page_size(h));
@@ -5980,7 +5980,7 @@ static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma,
/* Break COW or unshare */
huge_ptep_clear_flush(vma, haddr, ptep);
- page_remove_rmap(&old_folio->page, vma, true);
+ hugetlb_remove_rmap(old_folio);
hugetlb_add_new_anon_rmap(new_folio, vma, haddr);
if (huge_pte_uffd_wp(pte))
newpte = huge_pte_mkuffd_wp(newpte);
diff --git a/mm/rmap.c b/mm/rmap.c
index 112467c30b2c..5037581b79ec 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1440,13 +1440,6 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma,
VM_BUG_ON_PAGE(compound && !PageHead(page), page);
- /* Hugetlb pages are not counted in NR_*MAPPED */
- if (unlikely(folio_test_hugetlb(folio))) {
- /* hugetlb pages are always mapped with pmds */
- atomic_dec(&folio->_entire_mapcount);
- return;
- }
-
/* Is page being unmapped by PTE? Is this its last map to be removed? */
if (likely(!compound)) {
last = atomic_add_negative(-1, &page->_mapcount);
@@ -1804,7 +1797,10 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
dec_mm_counter(mm, mm_counter_file(&folio->page));
}
discard:
- page_remove_rmap(subpage, vma, folio_test_hugetlb(folio));
+ if (unlikely(folio_test_hugetlb(folio)))
+ hugetlb_remove_rmap(folio);
+ else
+ page_remove_rmap(subpage, vma, false);
if (vma->vm_flags & VM_LOCKED)
mlock_drain_local();
folio_put(folio);
@@ -2157,7 +2153,10 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
*/
}
- page_remove_rmap(subpage, vma, folio_test_hugetlb(folio));
+ if (unlikely(folio_test_hugetlb(folio)))
+ hugetlb_remove_rmap(folio);
+ else
+ page_remove_rmap(subpage, vma, false);
if (vma->vm_flags & VM_LOCKED)
mlock_drain_local();
folio_put(folio);
--
2.41.0
