[PATCH RFC 06/39] mm/rmap: add hugetlb sanity checks

[David Hildenbrand <david@xxxxxxxxxx>]

Let's make sure we end up with the right folios in the right functions.

Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
 include/linux/rmap.h | 7 +++++++
 mm/rmap.c            | 6 ++++++
 2 files changed, 13 insertions(+)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 3f38141b53b9d..77e336f86c72d 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -212,6 +212,7 @@ void hugetlb_add_new_anon_rmap(struct folio *, struct vm_area_struct *,
 static inline int hugetlb_try_dup_anon_rmap(struct folio *folio,
 		struct vm_area_struct *vma)
 {
+	VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);
 	VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio);
 
 	if (PageAnonExclusive(&folio->page)) {
@@ -226,6 +227,7 @@ static inline int hugetlb_try_dup_anon_rmap(struct folio *folio,
 /* See page_try_share_anon_rmap() */
 static inline int hugetlb_try_share_anon_rmap(struct folio *folio)
 {
+	VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);
 	VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio);
 	VM_WARN_ON_FOLIO(!PageAnonExclusive(&folio->page), folio);
 
@@ -245,6 +247,7 @@ static inline int hugetlb_try_share_anon_rmap(struct folio *folio)
 
 static inline void hugetlb_add_file_rmap(struct folio *folio)
 {
+	VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);
 	VM_WARN_ON_FOLIO(folio_test_anon(folio), folio);
 
 	atomic_inc(&folio->_entire_mapcount);
@@ -252,11 +255,15 @@ static inline void hugetlb_add_file_rmap(struct folio *folio)
 
 static inline void hugetlb_remove_rmap(struct folio *folio)
 {
+	VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);
+
 	atomic_dec(&folio->_entire_mapcount);
 }
 
 static inline void __page_dup_rmap(struct page *page, bool compound)
 {
+	VM_WARN_ON(folio_test_hugetlb(page_folio(page)));
+
 	if (compound) {
 		struct folio *folio = (struct folio *)page;
 
diff --git a/mm/rmap.c b/mm/rmap.c
index 2f1af3958e687..a735ecca47a81 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1313,6 +1313,7 @@ void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
 {
 	int nr;
 
+	VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio);
 	VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
 	__folio_set_swapbacked(folio);
 
@@ -1353,6 +1354,7 @@ void folio_add_file_rmap_range(struct folio *folio, struct page *page,
 	unsigned int nr_pmdmapped = 0, first;
 	int nr = 0;
 
+	VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio);
 	VM_WARN_ON_FOLIO(compound && !folio_test_pmd_mappable(folio), folio);
 
 	/* Is page being mapped by PTE? Is this its first map to be added? */
@@ -1438,6 +1440,7 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma,
 	bool last;
 	enum node_stat_item idx;
 
+	VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio);
 	VM_BUG_ON_PAGE(compound && !PageHead(page), page);
 
 	/* Is page being unmapped by PTE? Is this its last map to be removed? */
@@ -2590,6 +2593,7 @@ void rmap_walk_locked(struct folio *folio, struct rmap_walk_control *rwc)
 void hugetlb_add_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
 		unsigned long address, rmap_t flags)
 {
+	VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);
 	VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio);
 
 	atomic_inc(&folio->_entire_mapcount);
@@ -2602,6 +2606,8 @@ void hugetlb_add_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
 void hugetlb_add_new_anon_rmap(struct folio *folio,
 		struct vm_area_struct *vma, unsigned long address)
 {
+	VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);
+
 	BUG_ON(address < vma->vm_start || address >= vma->vm_end);
 	/* increment count (starts at -1) */
 	atomic_set(&folio->_entire_mapcount, 0);
-- 
2.41.0