mm: convert ptlock_alloc() to use ptdescs

This removes some direct accesses to struct page, working towards
splitting out struct ptdesc from struct page.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Vishal Moola (Oracle) <[email protected]>
Acked-by: Mike Rapoport (IBM) <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: Claudio Imbrenda <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Dinh Nguyen <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Guo Ren <[email protected]>
Cc: Huacai Chen <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: John Paul Adrian Glaubitz <[email protected]>
Cc: Jonas Bonn <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Palmer Dabbelt <[email protected]>
Cc: Paul Walmsley <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Thomas Bogendoerfer <[email protected]>
Cc: Yoshinori Sato <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

include/linux/mm.h

@@ -2826,7 +2826,7 @@ static inline void pagetable_free(struct ptdesc *pt)
 #if USE_SPLIT_PTE_PTLOCKS
 #if ALLOC_SPLIT_PTLOCKS
 void __init ptlock_cache_init(void);
-extern bool ptlock_alloc(struct page *page);
+bool ptlock_alloc(struct ptdesc *ptdesc);
 extern void ptlock_free(struct page *page);
 
 static inline spinlock_t *ptlock_ptr(struct page *page)
@@ -2838,7 +2838,7 @@ static inline void ptlock_cache_init(void)
 {
 }
 
-static inline bool ptlock_alloc(struct page *page)
+static inline bool ptlock_alloc(struct ptdesc *ptdesc)
 {
  return true;
 }
@@ -2868,7 +2868,7 @@ static inline bool ptlock_init(struct page *page)
  * slab code uses page->slab_cache, which share storage with page->ptl.
  */
  VM_BUG_ON_PAGE(*(unsigned long *)&page->ptl, page);
- if (!ptlock_alloc(page))
+ if (!ptlock_alloc(page_ptdesc(page)))
  return false;
  spin_lock_init(ptlock_ptr(page));
  return true;

mm/memory.c

@@ -6114,14 +6114,14 @@ void __init ptlock_cache_init(void)
  SLAB_PANIC, NULL);
 }
 
-bool ptlock_alloc(struct page *page)
+bool ptlock_alloc(struct ptdesc *ptdesc)
 {
  spinlock_t *ptl;
 
  ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
  if (!ptl)
  return false;
- page->ptl = ptl;
+ ptdesc->ptl = ptl;
  return true;
 }