[RFC PATCH 3/7] mm: Mark pagetable memory when allocated

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

Move the page type setting from the constructor to the allocation site.
Some of the architecture code is a little complex to reason about, but
I think this is all correct.  This makes __pagetable_ctor() empty, so
remove it.  While pagetable_pud_ctor() and higher levels are now empty,
leave them alone as there may be call to have them do something in future.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/mm.h | 11 -----------
 mm/memory.c        |  2 ++
 2 files changed, 2 insertions(+), 11 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index ade37df5ea2b..edcb7d75542f 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3044,15 +3044,9 @@ static inline bool ptlock_init(struct ptdesc *ptdesc) { return true; }
 static inline void ptlock_free(struct ptdesc *ptdesc) {}
 #endif /* defined(CONFIG_SPLIT_PTE_PTLOCKS) */
 
-static inline void __pagetable_ctor(struct ptdesc *ptdesc)
-{
-	__SetPageTable(ptdesc_page(ptdesc));
-}
-
 static inline void pagetable_dtor(struct ptdesc *ptdesc)
 {
 	ptlock_free(ptdesc);
-	__ClearPageTable(ptdesc_page(ptdesc));
 }
 
 static inline void pagetable_dtor_free(struct ptdesc *ptdesc)
@@ -3066,7 +3060,6 @@ static inline bool pagetable_pte_ctor(struct mm_struct *mm,
 {
 	if (mm != &init_mm && !ptlock_init(ptdesc))
 		return false;
-	__pagetable_ctor(ptdesc);
 	return true;
 }
 
@@ -3174,7 +3167,6 @@ static inline bool pagetable_pmd_ctor(struct mm_struct *mm,
 	if (mm != &init_mm && !pmd_ptlock_init(ptdesc))
 		return false;
 	ptdesc_pmd_pts_init(ptdesc);
-	__pagetable_ctor(ptdesc);
 	return true;
 }
 
@@ -3199,17 +3191,14 @@ static inline spinlock_t *pud_lock(struct mm_struct *mm, pud_t *pud)
 
 static inline void pagetable_pud_ctor(struct ptdesc *ptdesc)
 {
-	__pagetable_ctor(ptdesc);
 }
 
 static inline void pagetable_p4d_ctor(struct ptdesc *ptdesc)
 {
-	__pagetable_ctor(ptdesc);
 }
 
 static inline void pagetable_pgd_ctor(struct ptdesc *ptdesc)
 {
-	__pagetable_ctor(ptdesc);
 }
 
 extern void __init pagecache_init(void);
diff --git a/mm/memory.c b/mm/memory.c
index 033fc4e29232..47eb5834db23 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -7287,6 +7287,7 @@ struct ptdesc *pagetable_alloc_noprof(gfp_t gfp, unsigned int order)
 
 	pgdat = NODE_DATA(page_to_nid(page));
 	mod_node_page_state(pgdat, NR_PAGETABLE, 1 << order);
+	__SetPageTable(page);
 	return page_ptdesc(page);
 }
 
@@ -7304,6 +7305,7 @@ void pagetable_free(struct ptdesc *pt)
 	unsigned int order = compound_order(page);
 
 	mod_node_page_state(pgdat, NR_PAGETABLE, -(1L << order));
+	__ClearPageTable(page);
 	free_frozen_pages(page, order);
 }
 
-- 
2.47.2