mm: re-unify the simplified page_zap_*_rmap() function

Now that we've simplified both the anonymous and file-backed page zap
functions, they end up being identical except for which page statistic
they update, and we can re-unify the implementation of that much
simplified code.

To make it very clear that this is only for the final pte zapping (since
a lot of the simplifications depended on that), name the unified
function 'page_zap_pte_rmap()'.

Link: https://lore.kernel.org/all/B88D3073-440A-41C7-95F4-895D3F657EF2@gmail.com/
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 12 insertions, 35 deletions

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 8d29b7c38368..f62af001707c 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -196,8 +196,7 @@ void page_add_new_anon_rmap(struct page *, struct vm_area_struct *,
 		unsigned long address);
 void page_add_file_rmap(struct page *, struct vm_area_struct *,
 		bool compound);
-void page_zap_file_rmap(struct page *);
-void page_zap_anon_rmap(struct page *);
+void page_zap_pte_rmap(struct page *);
 void page_remove_rmap(struct page *, struct vm_area_struct *,
 		bool compound);
 
diff --git a/mm/memory.c b/mm/memory.c
index ba1d08a908a4..c893f5ffc5a8 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1451,9 +1451,8 @@ again:
 				if (pte_young(ptent) &&
 				    likely(!(vma->vm_flags & VM_SEQ_READ)))
 					mark_page_accessed(page);
-				page_zap_file_rmap(page);
-			} else
-				page_zap_anon_rmap(page);
+			}
+			page_zap_pte_rmap(page);
 			munlock_vma_page(page, vma, false);
 			rss[mm_counter(page)]--;
 			if (unlikely(page_mapcount(page) < 0))
diff --git a/mm/rmap.c b/mm/rmap.c
index 69de6c833d5c..28b51a31ebb0 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1413,47 +1413,26 @@ static void page_remove_anon_compound_rmap(struct page *page)
 }
 
 /**
- * page_zap_file_rmap - take down non-anon pte mapping from a page
+ * page_zap_pte_rmap - take down a pte mapping from a page
  * @page:	page to remove mapping from
  *
- * This is the simplified form of page_remove_rmap(), with:
- *  - we've already checked for '!PageAnon(page)'
- *  - 'compound' is always false
- *  - the caller does 'munlock_vma_page(page, vma, compound)' separately
- * which allows for a much simpler calling convention.
+ * This is the simplified form of page_remove_rmap(), that only
+ * deals with last-level pages, so 'compound' is always false,
+ * and the caller does 'munlock_vma_page(page, vma, compound)'
+ * separately.
  *
- * The caller holds the pte lock.
- */
-void page_zap_file_rmap(struct page *page)
-{
-	if (!atomic_add_negative(-1, &page->_mapcount))
-		return;
-
-	lock_page_memcg(page);
-	__dec_lruvec_page_state(page, NR_FILE_MAPPED);
-	unlock_page_memcg(page);
-}
-
-/**
- * page_zap_anon_rmap(page) - take down non-anon pte mapping from a page
- * @page:	page to remove mapping from
- *
- * This is the simplified form of page_remove_rmap(), with:
- *  - we've already checked for 'PageAnon(page)'
- *  - 'compound' is always false
- *  - the caller does 'munlock_vma_page(page, vma, compound)' separately
- * which allows for a much simpler calling convention.
+ * This allows for a much simpler calling convention and code.
  *
  * The caller holds the pte lock.
  */
-void page_zap_anon_rmap(struct page *page)
+void page_zap_pte_rmap(struct page *page)
 {
-	/* page still mapped by someone else? */
 	if (!atomic_add_negative(-1, &page->_mapcount))
 		return;
 
 	lock_page_memcg(page);
-	__dec_lruvec_page_state(page, NR_ANON_MAPPED);
+	__dec_lruvec_page_state(page,
+		PageAnon(page) ? NR_ANON_MAPPED : NR_FILE_MAPPED);
 	unlock_page_memcg(page);
 }