mm: introduce compound_nr()

Replace 1 << compound_order(page) with compound_nr(page).  Minor
improvements in readability.

Link: http://lkml.kernel.org/r/20190721104612.19120-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
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>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

18 files changed, 30 insertions, 25 deletions

diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c
index 4c7ebe094a83..6d89db7895d1 100644
--- a/arch/arm/mm/flush.c
+++ b/arch/arm/mm/flush.c
@@ -208,13 +208,13 @@ void __flush_dcache_page(struct address_space *mapping, struct page *page)
 	} else {
 		unsigned long i;
 		if (cache_is_vipt_nonaliasing()) {
-			for (i = 0; i < (1 << compound_order(page)); i++) {
+			for (i = 0; i < compound_nr(page); i++) {
 				void *addr = kmap_atomic(page + i);
 				__cpuc_flush_dcache_area(addr, PAGE_SIZE);
 				kunmap_atomic(addr);
 			}
 		} else {
-			for (i = 0; i < (1 << compound_order(page)); i++) {
+			for (i = 0; i < compound_nr(page); i++) {
 				void *addr = kmap_high_get(page + i);
 				if (addr) {
 					__cpuc_flush_dcache_area(addr, PAGE_SIZE);
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index a8953f108808..73d4873fc7f8 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -667,7 +667,7 @@ void flush_dcache_icache_hugepage(struct page *page)
 
 	BUG_ON(!PageCompound(page));
 
-	for (i = 0; i < (1UL << compound_order(page)); i++) {
+	for (i = 0; i < compound_nr(page); i++) {
 		if (!PageHighMem(page)) {
 			__flush_dcache_icache(page_address(page+i));
 		} else {
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index bf43d1d60059..ea1630465474 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -461,7 +461,7 @@ static void smaps_page_accumulate(struct mem_size_stats *mss,
 static void smaps_account(struct mem_size_stats *mss, struct page *page,
 		bool compound, bool young, bool dirty, bool locked)
 {
-	int i, nr = compound ? 1 << compound_order(page) : 1;
+	int i, nr = compound ? compound_nr(page) : 1;
 	unsigned long size = nr * PAGE_SIZE;
 
 	/*
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 9238548bdec5..69b7314c8d24 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -805,6 +805,12 @@ static inline void set_compound_order(struct page *page, unsigned int order)
 	page[1].compound_order = order;
 }
 
+/* Returns the number of pages in this potentially compound page. */
+static inline unsigned long compound_nr(struct page *page)
+{
+	return 1UL << compound_order(page);
+}
+
 /* Returns the number of bytes in this potentially compound page. */
 static inline unsigned long page_size(struct page *page)
 {
diff --git a/mm/compaction.c b/mm/compaction.c
index 952dc2fb24e5..777c088e9113 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -969,7 +969,7 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 			 * is safe to read and it's 0 for tail pages.
 			 */
 			if (unlikely(PageCompound(page))) {
-				low_pfn += (1UL << compound_order(page)) - 1;
+				low_pfn += compound_nr(page) - 1;
 				goto isolate_fail;
 			}
 		}
diff --git a/mm/filemap.c b/mm/filemap.c
index 40667c2f3383..5f30aedd7363 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -126,7 +126,7 @@ static void page_cache_delete(struct address_space *mapping,
 	/* hugetlb pages are represented by a single entry in the xarray */
 	if (!PageHuge(page)) {
 		xas_set_order(&xas, page->index, compound_order(page));
-		nr = 1U << compound_order(page);
+		nr = compound_nr(page);
 	}
 
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
diff --git a/mm/gup.c b/mm/gup.c
index 98f13ab37bac..84a36d80dd2e 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1460,7 +1460,7 @@ check_again:
 		 * gup may start from a tail page. Advance step by the left
 		 * part.
 		 */
-		step = (1 << compound_order(head)) - (pages[i] - head);
+		step = compound_nr(head) - (pages[i] - head);
 		/*
 		 * If we get a page from the CMA zone, since we are going to
 		 * be pinning these entries, we might as well move them out
diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
index 68c2f2f3c05b..f1930fa0b445 100644
--- a/mm/hugetlb_cgroup.c
+++ b/mm/hugetlb_cgroup.c
@@ -139,7 +139,7 @@ static void hugetlb_cgroup_move_parent(int idx, struct hugetlb_cgroup *h_cg,
 	if (!page_hcg || page_hcg != h_cg)
 		goto out;
 
-	nr_pages = 1 << compound_order(page);
+	nr_pages = compound_nr(page);
 	if (!parent) {
 		parent = root_h_cgroup;
 		/* root has no limit */
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 307631d9c62b..6814d6d6a023 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -336,7 +336,7 @@ void kasan_poison_slab(struct page *page)
 {
 	unsigned long i;
 
-	for (i = 0; i < (1 << compound_order(page)); i++)
+	for (i = 0; i < compound_nr(page); i++)
 		page_kasan_tag_reset(page + i);
 	kasan_poison_shadow(page_address(page), page_size(page),
 			KASAN_KMALLOC_REDZONE);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f3c15bb07cce..6c6032c03d1d 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6511,7 +6511,7 @@ static void uncharge_page(struct page *page, struct uncharge_gather *ug)
 		unsigned int nr_pages = 1;
 
 		if (PageTransHuge(page)) {
-			nr_pages <<= compound_order(page);
+			nr_pages = compound_nr(page);
 			ug->nr_huge += nr_pages;
 		}
 		if (PageAnon(page))
@@ -6523,7 +6523,7 @@ static void uncharge_page(struct page *page, struct uncharge_gather *ug)
 		}
 		ug->pgpgout++;
 	} else {
-		ug->nr_kmem += 1 << compound_order(page);
+		ug->nr_kmem += compound_nr(page);
 		__ClearPageKmemcg(page);
 	}
 
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index c73f09913165..5f2c83ce9fde 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1309,7 +1309,7 @@ static unsigned long scan_movable_pages(unsigned long start, unsigned long end)
 		head = compound_head(page);
 		if (page_huge_active(head))
 			return pfn;
-		skip = (1 << compound_order(head)) - (page - head);
+		skip = compound_nr(head) - (page - head);
 		pfn += skip - 1;
 	}
 	return 0;
@@ -1347,7 +1347,7 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
 
 		if (PageHuge(page)) {
 			struct page *head = compound_head(page);
-			pfn = page_to_pfn(head) + (1<<compound_order(head)) - 1;
+			pfn = page_to_pfn(head) + compound_nr(head) - 1;
 			isolate_huge_page(head, &source);
 			continue;
 		} else if (PageTransHuge(page))
diff --git a/mm/migrate.c b/mm/migrate.c
index 9f4ed4e985c1..aa72b49e0209 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1892,7 +1892,7 @@ static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
 	VM_BUG_ON_PAGE(compound_order(page) && !PageTransHuge(page), page);
 
 	/* Avoid migrating to a node that is nearly full */
-	if (!migrate_balanced_pgdat(pgdat, 1UL << compound_order(page)))
+	if (!migrate_balanced_pgdat(pgdat, compound_nr(page)))
 		return 0;
 
 	if (isolate_lru_page(page))
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ff5484fdbdf9..df566c0f6729 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8196,7 +8196,7 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
 			if (!hugepage_migration_supported(page_hstate(head)))
 				goto unmovable;
 
-			skip_pages = (1 << compound_order(head)) - (page - head);
+			skip_pages = compound_nr(head) - (page - head);
 			iter += skip_pages - 1;
 			continue;
 		}
diff --git a/mm/rmap.c b/mm/rmap.c
index f401732b20e8..26006445c8b5 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1520,8 +1520,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 		if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
 			pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
 			if (PageHuge(page)) {
-				int nr = 1 << compound_order(page);
-				hugetlb_count_sub(nr, mm);
+				hugetlb_count_sub(compound_nr(page), mm);
 				set_huge_swap_pte_at(mm, address,
 						     pvmw.pte, pteval,
 						     vma_mmu_pagesize(vma));
diff --git a/mm/shmem.c b/mm/shmem.c
index 0f7fd4a85db6..15d26c86e5ef 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -609,7 +609,7 @@ static int shmem_add_to_page_cache(struct page *page,
 {
 	XA_STATE_ORDER(xas, &mapping->i_pages, index, compound_order(page));
 	unsigned long i = 0;
-	unsigned long nr = 1UL << compound_order(page);
+	unsigned long nr = compound_nr(page);
 
 	VM_BUG_ON_PAGE(PageTail(page), page);
 	VM_BUG_ON_PAGE(index != round_down(index, nr), page);
@@ -1884,7 +1884,7 @@ alloc_nohuge:
 	lru_cache_add_anon(page);
 
 	spin_lock_irq(&info->lock);
-	info->alloced += 1 << compound_order(page);
+	info->alloced += compound_nr(page);
 	inode->i_blocks += BLOCKS_PER_PAGE << compound_order(page);
 	shmem_recalc_inode(inode);
 	spin_unlock_irq(&info->lock);
@@ -1925,7 +1925,7 @@ clear:
 		struct page *head = compound_head(page);
 		int i;
 
-		for (i = 0; i < (1 << compound_order(head)); i++) {
+		for (i = 0; i < compound_nr(head); i++) {
 			clear_highpage(head + i);
 			flush_dcache_page(head + i);
 		}
@@ -1952,7 +1952,7 @@ clear:
 	 * Error recovery.
 	 */
 unacct:
-	shmem_inode_unacct_blocks(inode, 1 << compound_order(page));
+	shmem_inode_unacct_blocks(inode, compound_nr(page));
 
 	if (PageTransHuge(page)) {
 		unlock_page(page);
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 8368621a0fc7..f844af5f09ba 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -116,7 +116,7 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp)
 	struct address_space *address_space = swap_address_space(entry);
 	pgoff_t idx = swp_offset(entry);
 	XA_STATE_ORDER(xas, &address_space->i_pages, idx, compound_order(page));
-	unsigned long i, nr = 1UL << compound_order(page);
+	unsigned long i, nr = compound_nr(page);
 
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
 	VM_BUG_ON_PAGE(PageSwapCache(page), page);
diff --git a/mm/util.c b/mm/util.c
index e6351a80f248..bab284d69c8c 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -521,7 +521,7 @@ bool page_mapped(struct page *page)
 		return true;
 	if (PageHuge(page))
 		return false;
-	for (i = 0; i < (1 << compound_order(page)); i++) {
+	for (i = 0; i < compound_nr(page); i++) {
 		if (atomic_read(&page[i]._mapcount) >= 0)
 			return true;
 	}
diff --git a/mm/vmscan.c b/mm/vmscan.c
index a6c5d0b28321..8e03427cb64f 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1149,7 +1149,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 
 		VM_BUG_ON_PAGE(PageActive(page), page);
 
-		nr_pages = 1 << compound_order(page);
+		nr_pages = compound_nr(page);
 
 		/* Account the number of base pages even though THP */
 		sc->nr_scanned += nr_pages;
@@ -1705,7 +1705,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
 
 		VM_BUG_ON_PAGE(!PageLRU(page), page);
 
-		nr_pages = 1 << compound_order(page);
+		nr_pages = compound_nr(page);
 		total_scan += nr_pages;
 
 		if (page_zonenum(page) > sc->reclaim_idx) {