mm: introduce page_size()

Patch series "Make working with compound pages easier", v2.

These three patches add three helpers and convert the appropriate
places to use them.

This patch (of 3):

It's unnecessarily hard to find out the size of a potentially huge page.
Replace 'PAGE_SIZE << compound_order(page)' with page_size(page).

Link: http://lkml.kernel.org/r/20190721104612.19120-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/kasan/common.c

@@ -338,8 +338,7 @@ void kasan_poison_slab(struct page *page)
 
 	for (i = 0; i < (1 << compound_order(page)); i++)
 		page_kasan_tag_reset(page + i);
-	kasan_poison_shadow(page_address(page),
-			PAGE_SIZE << compound_order(page),
+	kasan_poison_shadow(page_address(page), page_size(page),
 			KASAN_KMALLOC_REDZONE);
 }
 
@@ -542,7 +541,7 @@ void * __must_check kasan_kmalloc_large(const void *ptr, size_t size,
 	page = virt_to_page(ptr);
 	redzone_start = round_up((unsigned long)(ptr + size),
 				KASAN_SHADOW_SCALE_SIZE);
-	redzone_end = (unsigned long)ptr + (PAGE_SIZE << compound_order(page));
+	redzone_end = (unsigned long)ptr + page_size(page);
 
 	kasan_unpoison_shadow(ptr, size);
 	kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
@@ -578,8 +577,7 @@ void kasan_poison_kfree(void *ptr, unsigned long ip)
 			kasan_report_invalid_free(ptr, ip);
 			return;
 		}
-		kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
-				KASAN_FREE_PAGE);
+		kasan_poison_shadow(ptr, page_size(page), KASAN_FREE_PAGE);
 	} else {
 		__kasan_slab_free(page->slab_cache, ptr, ip, false);
 	}

mm/nommu.c

@@ -108,7 +108,7 @@ unsigned int kobjsize(const void *objp)
 	 * The ksize() function is only guaranteed to work for pointers
 	 * returned by kmalloc(). So handle arbitrary pointers here.
 	 */
-	return PAGE_SIZE << compound_order(page);
+	return page_size(page);
 }
 
 /**

mm/page_vma_mapped.c

@@ -153,8 +153,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
 
 	if (unlikely(PageHuge(pvmw->page))) {
 		/* when pud is not present, pte will be NULL */
-		pvmw->pte = huge_pte_offset(mm, pvmw->address,
-					    PAGE_SIZE << compound_order(page));
+		pvmw->pte = huge_pte_offset(mm, pvmw->address, page_size(page));
 		if (!pvmw->pte)
 			return false;
 

mm/rmap.c

@@ -898,8 +898,7 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
 	 */
 	mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE,
 				0, vma, vma->vm_mm, address,
-				min(vma->vm_end, address +
-				    (PAGE_SIZE << compound_order(page))));
+				min(vma->vm_end, address + page_size(page)));
 	mmu_notifier_invalidate_range_start(&range);
 
 	while (page_vma_mapped_walk(&pvmw)) {
@@ -1372,8 +1371,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 	 */
 	mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
 				address,
-				min(vma->vm_end, address +
-				    (PAGE_SIZE << compound_order(page))));
+				min(vma->vm_end, address + page_size(page)));
 	if (PageHuge(page)) {
 		/*
 		 * If sharing is possible, start and end will be adjusted

mm/slob.c

@@ -539,7 +539,7 @@ size_t __ksize(const void *block)
 
 	sp = virt_to_page(block);
 	if (unlikely(!PageSlab(sp)))
-		return PAGE_SIZE << compound_order(sp);
+		return page_size(sp);
 
 	align = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
 	m = (unsigned int *)(block - align);

mm/slub.c

@@ -829,7 +829,7 @@ static int slab_pad_check(struct kmem_cache *s, struct page *page)
 		return 1;
 
 	start = page_address(page);
-	length = PAGE_SIZE << compound_order(page);
+	length = page_size(page);
 	end = start + length;
 	remainder = length % s->size;
 	if (!remainder)
@@ -1074,13 +1074,14 @@ static void setup_object_debug(struct kmem_cache *s, struct page *page,
 	init_tracking(s, object);
 }
 
-static void setup_page_debug(struct kmem_cache *s, void *addr, int order)
+static
+void setup_page_debug(struct kmem_cache *s, struct page *page, void *addr)
 {
 	if (!(s->flags & SLAB_POISON))
 		return;
 
 	metadata_access_enable();
-	memset(addr, POISON_INUSE, PAGE_SIZE << order);
+	memset(addr, POISON_INUSE, page_size(page));
 	metadata_access_disable();
 }
 
@@ -1340,8 +1341,8 @@ slab_flags_t kmem_cache_flags(unsigned int object_size,
 #else /* !CONFIG_SLUB_DEBUG */
 static inline void setup_object_debug(struct kmem_cache *s,
 			struct page *page, void *object) {}
-static inline void setup_page_debug(struct kmem_cache *s,
-			void *addr, int order) {}
+static inline
+void setup_page_debug(struct kmem_cache *s, struct page *page, void *addr) {}
 
 static inline int alloc_debug_processing(struct kmem_cache *s,
 	struct page *page, void *object, unsigned long addr) { return 0; }
@@ -1639,7 +1640,7 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
 	struct kmem_cache_order_objects oo = s->oo;
 	gfp_t alloc_gfp;
 	void *start, *p, *next;
-	int idx, order;
+	int idx;
 	bool shuffle;
 
 	flags &= gfp_allowed_mask;
@@ -1673,7 +1674,6 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
 
 	page->objects = oo_objects(oo);
 
-	order = compound_order(page);
 	page->slab_cache = s;
 	__SetPageSlab(page);
 	if (page_is_pfmemalloc(page))
@@ -1683,7 +1683,7 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
 
 	start = page_address(page);
 
-	setup_page_debug(s, start, order);
+	setup_page_debug(s, page, start);
 
 	shuffle = shuffle_freelist(s, page);
 
@@ -3932,7 +3932,7 @@ size_t __ksize(const void *object)
 
 	if (unlikely(!PageSlab(page))) {
 		WARN_ON(!PageCompound(page));
-		return PAGE_SIZE << compound_order(page);
+		return page_size(page);
 	}
 
 	return slab_ksize(page->slab_cache);