1 files changed, 535 insertions, 350 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c1069efcc4d7..5c469c1dfb8b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -352,6 +352,106 @@ static inline bool update_defer_init(pg_data_t *pgdat,
 }
 #endif
 
+/* Return a pointer to the bitmap storing bits affecting a block of pages */
+static inline unsigned long *get_pageblock_bitmap(struct page *page,
+							unsigned long pfn)
+{
+#ifdef CONFIG_SPARSEMEM
+	return __pfn_to_section(pfn)->pageblock_flags;
+#else
+	return page_zone(page)->pageblock_flags;
+#endif /* CONFIG_SPARSEMEM */
+}
+
+static inline int pfn_to_bitidx(struct page *page, unsigned long pfn)
+{
+#ifdef CONFIG_SPARSEMEM
+	pfn &= (PAGES_PER_SECTION-1);
+	return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
+#else
+	pfn = pfn - round_down(page_zone(page)->zone_start_pfn, pageblock_nr_pages);
+	return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
+#endif /* CONFIG_SPARSEMEM */
+}
+
+/**
+ * get_pfnblock_flags_mask - Return the requested group of flags for the pageblock_nr_pages block of pages
+ * @page: The page within the block of interest
+ * @pfn: The target page frame number
+ * @end_bitidx: The last bit of interest to retrieve
+ * @mask: mask of bits that the caller is interested in
+ *
+ * Return: pageblock_bits flags
+ */
+static __always_inline unsigned long __get_pfnblock_flags_mask(struct page *page,
+					unsigned long pfn,
+					unsigned long end_bitidx,
+					unsigned long mask)
+{
+	unsigned long *bitmap;
+	unsigned long bitidx, word_bitidx;
+	unsigned long word;
+
+	bitmap = get_pageblock_bitmap(page, pfn);
+	bitidx = pfn_to_bitidx(page, pfn);
+	word_bitidx = bitidx / BITS_PER_LONG;
+	bitidx &= (BITS_PER_LONG-1);
+
+	word = bitmap[word_bitidx];
+	bitidx += end_bitidx;
+	return (word >> (BITS_PER_LONG - bitidx - 1)) & mask;
+}
+
+unsigned long get_pfnblock_flags_mask(struct page *page, unsigned long pfn,
+					unsigned long end_bitidx,
+					unsigned long mask)
+{
+	return __get_pfnblock_flags_mask(page, pfn, end_bitidx, mask);
+}
+
+static __always_inline int get_pfnblock_migratetype(struct page *page, unsigned long pfn)
+{
+	return __get_pfnblock_flags_mask(page, pfn, PB_migrate_end, MIGRATETYPE_MASK);
+}
+
+/**
+ * set_pfnblock_flags_mask - Set the requested group of flags for a pageblock_nr_pages block of pages
+ * @page: The page within the block of interest
+ * @flags: The flags to set
+ * @pfn: The target page frame number
+ * @end_bitidx: The last bit of interest
+ * @mask: mask of bits that the caller is interested in
+ */
+void set_pfnblock_flags_mask(struct page *page, unsigned long flags,
+					unsigned long pfn,
+					unsigned long end_bitidx,
+					unsigned long mask)
+{
+	unsigned long *bitmap;
+	unsigned long bitidx, word_bitidx;
+	unsigned long old_word, word;
+
+	BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4);
+
+	bitmap = get_pageblock_bitmap(page, pfn);
+	bitidx = pfn_to_bitidx(page, pfn);
+	word_bitidx = bitidx / BITS_PER_LONG;
+	bitidx &= (BITS_PER_LONG-1);
+
+	VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page);
+
+	bitidx += end_bitidx;
+	mask <<= (BITS_PER_LONG - bitidx - 1);
+	flags <<= (BITS_PER_LONG - bitidx - 1);
+
+	word = READ_ONCE(bitmap[word_bitidx]);
+	for (;;) {
+		old_word = cmpxchg(&bitmap[word_bitidx], word, (word & ~mask) | flags);
+		if (word == old_word)
+			break;
+		word = old_word;
+	}
+}
 
 void set_pageblock_migratetype(struct page *page, int migratetype)
 {
@@ -784,17 +884,42 @@ out:
 	zone->free_area[order].nr_free++;
 }
 
-static inline int free_pages_check(struct page *page)
+/*
+ * A bad page could be due to a number of fields. Instead of multiple branches,
+ * try and check multiple fields with one check. The caller must do a detailed
+ * check if necessary.
+ */
+static inline bool page_expected_state(struct page *page,
+					unsigned long check_flags)
 {
-	const char *bad_reason = NULL;
-	unsigned long bad_flags = 0;
+	if (unlikely(atomic_read(&page->_mapcount) != -1))
+		return false;
+
+	if (unlikely((unsigned long)page->mapping |
+			page_ref_count(page) |
+#ifdef CONFIG_MEMCG
+			(unsigned long)page->mem_cgroup |
+#endif
+			(page->flags & check_flags)))
+		return false;
+
+	return true;
+}
+
+static void free_pages_check_bad(struct page *page)
+{
+	const char *bad_reason;
+	unsigned long bad_flags;
+
+	bad_reason = NULL;
+	bad_flags = 0;
 
 	if (unlikely(atomic_read(&page->_mapcount) != -1))
 		bad_reason = "nonzero mapcount";
 	if (unlikely(page->mapping != NULL))
 		bad_reason = "non-NULL mapping";
 	if (unlikely(page_ref_count(page) != 0))
-		bad_reason = "nonzero _count";
+		bad_reason = "nonzero _refcount";
 	if (unlikely(page->flags & PAGE_FLAGS_CHECK_AT_FREE)) {
 		bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set";
 		bad_flags = PAGE_FLAGS_CHECK_AT_FREE;
@@ -803,16 +928,146 @@ static inline int free_pages_check(struct page *page)
 	if (unlikely(page->mem_cgroup))
 		bad_reason = "page still charged to cgroup";
 #endif
-	if (unlikely(bad_reason)) {
-		bad_page(page, bad_reason, bad_flags);
-		return 1;
+	bad_page(page, bad_reason, bad_flags);
+}
+
+static inline int free_pages_check(struct page *page)
+{
+	if (likely(page_expected_state(page, PAGE_FLAGS_CHECK_AT_FREE)))
+		return 0;
+
+	/* Something has gone sideways, find it */
+	free_pages_check_bad(page);
+	return 1;
+}
+
+static int free_tail_pages_check(struct page *head_page, struct page *page)
+{
+	int ret = 1;
+
+	/*
+	 * We rely page->lru.next never has bit 0 set, unless the page
+	 * is PageTail(). Let's make sure that's true even for poisoned ->lru.
+	 */
+	BUILD_BUG_ON((unsigned long)LIST_POISON1 & 1);
+
+	if (!IS_ENABLED(CONFIG_DEBUG_VM)) {
+		ret = 0;
+		goto out;
 	}
+	switch (page - head_page) {
+	case 1:
+		/* the first tail page: ->mapping is compound_mapcount() */
+		if (unlikely(compound_mapcount(page))) {
+			bad_page(page, "nonzero compound_mapcount", 0);
+			goto out;
+		}
+		break;
+	case 2:
+		/*
+		 * the second tail page: ->mapping is
+		 * page_deferred_list().next -- ignore value.
+		 */
+		break;
+	default:
+		if (page->mapping != TAIL_MAPPING) {
+			bad_page(page, "corrupted mapping in tail page", 0);
+			goto out;
+		}
+		break;
+	}
+	if (unlikely(!PageTail(page))) {
+		bad_page(page, "PageTail not set", 0);
+		goto out;
+	}
+	if (unlikely(compound_head(page) != head_page)) {
+		bad_page(page, "compound_head not consistent", 0);
+		goto out;
+	}
+	ret = 0;
+out:
+	page->mapping = NULL;
+	clear_compound_head(page);
+	return ret;
+}
+
+static __always_inline bool free_pages_prepare(struct page *page,
+					unsigned int order, bool check_free)
+{
+	int bad = 0;
+
+	VM_BUG_ON_PAGE(PageTail(page), page);
+
+	trace_mm_page_free(page, order);
+	kmemcheck_free_shadow(page, order);
+	kasan_free_pages(page, order);
+
+	/*
+	 * Check tail pages before head page information is cleared to
+	 * avoid checking PageCompound for order-0 pages.
+	 */
+	if (unlikely(order)) {
+		bool compound = PageCompound(page);
+		int i;
+
+		VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
+
+		for (i = 1; i < (1 << order); i++) {
+			if (compound)
+				bad += free_tail_pages_check(page, page + i);
+			if (unlikely(free_pages_check(page + i))) {
+				bad++;
+				continue;
+			}
+			(page + i)->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
+		}
+	}
+	if (PageAnonHead(page))
+		page->mapping = NULL;
+	if (check_free)
+		bad += free_pages_check(page);
+	if (bad)
+		return false;
+
 	page_cpupid_reset_last(page);
-	if (page->flags & PAGE_FLAGS_CHECK_AT_PREP)
-		page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
-	return 0;
+	page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
+	reset_page_owner(page, order);
+
+	if (!PageHighMem(page)) {
+		debug_check_no_locks_freed(page_address(page),
+					   PAGE_SIZE << order);
+		debug_check_no_obj_freed(page_address(page),
+					   PAGE_SIZE << order);
+	}
+	arch_free_page(page, order);
+	kernel_poison_pages(page, 1 << order, 0);
+	kernel_map_pages(page, 1 << order, 0);
+
+	return true;
 }
 
+#ifdef CONFIG_DEBUG_VM
+static inline bool free_pcp_prepare(struct page *page)
+{
+	return free_pages_prepare(page, 0, true);
+}
+
+static inline bool bulkfree_pcp_prepare(struct page *page)
+{
+	return false;
+}
+#else
+static bool free_pcp_prepare(struct page *page)
+{
+	return free_pages_prepare(page, 0, false);
+}
+
+static bool bulkfree_pcp_prepare(struct page *page)
+{
+	return free_pages_check(page);
+}
+#endif /* CONFIG_DEBUG_VM */
+
 /*
  * Frees a number of pages from the PCP lists
  * Assumes all pages on list are in same zone, and of same order.
@@ -829,15 +1084,16 @@ static void free_pcppages_bulk(struct zone *zone, int count,
 {
 	int migratetype = 0;
 	int batch_free = 0;
-	int to_free = count;
 	unsigned long nr_scanned;
+	bool isolated_pageblocks;
 
 	spin_lock(&zone->lock);
+	isolated_pageblocks = has_isolate_pageblock(zone);
 	nr_scanned = zone_page_state(zone, NR_PAGES_SCANNED);
 	if (nr_scanned)
 		__mod_zone_page_state(zone, NR_PAGES_SCANNED, -nr_scanned);
 
-	while (to_free) {
+	while (count) {
 		struct page *page;
 		struct list_head *list;
 
@@ -857,7 +1113,7 @@ static void free_pcppages_bulk(struct zone *zone, int count,
 
 		/* This is the only non-empty list. Free them all. */
 		if (batch_free == MIGRATE_PCPTYPES)
-			batch_free = to_free;
+			batch_free = count;
 
 		do {
 			int mt;	/* migratetype of the to-be-freed page */
@@ -870,12 +1126,15 @@ static void free_pcppages_bulk(struct zone *zone, int count,
 			/* MIGRATE_ISOLATE page should not go to pcplists */
 			VM_BUG_ON_PAGE(is_migrate_isolate(mt), page);
 			/* Pageblock could have been isolated meanwhile */
-			if (unlikely(has_isolate_pageblock(zone)))
+			if (unlikely(isolated_pageblocks))
 				mt = get_pageblock_migratetype(page);
 
+			if (bulkfree_pcp_prepare(page))
+				continue;
+
 			__free_one_page(page, page_to_pfn(page), zone, 0, mt);
 			trace_mm_page_pcpu_drain(page, 0, mt);
-		} while (--to_free && --batch_free && !list_empty(list));
+		} while (--count && --batch_free && !list_empty(list));
 	}
 	spin_unlock(&zone->lock);
 }
@@ -899,56 +1158,6 @@ static void free_one_page(struct zone *zone,
 	spin_unlock(&zone->lock);
 }
 
-static int free_tail_pages_check(struct page *head_page, struct page *page)
-{
-	int ret = 1;
-
-	/*
-	 * We rely page->lru.next never has bit 0 set, unless the page
-	 * is PageTail(). Let's make sure that's true even for poisoned ->lru.
-	 */
-	BUILD_BUG_ON((unsigned long)LIST_POISON1 & 1);
-
-	if (!IS_ENABLED(CONFIG_DEBUG_VM)) {
-		ret = 0;
-		goto out;
-	}
-	switch (page - head_page) {
-	case 1:
-		/* the first tail page: ->mapping is compound_mapcount() */
-		if (unlikely(compound_mapcount(page))) {
-			bad_page(page, "nonzero compound_mapcount", 0);
-			goto out;
-		}
-		break;
-	case 2:
-		/*
-		 * the second tail page: ->mapping is
-		 * page_deferred_list().next -- ignore value.
-		 */
-		break;
-	default:
-		if (page->mapping != TAIL_MAPPING) {
-			bad_page(page, "corrupted mapping in tail page", 0);
-			goto out;
-		}
-		break;
-	}
-	if (unlikely(!PageTail(page))) {
-		bad_page(page, "PageTail not set", 0);
-		goto out;
-	}
-	if (unlikely(compound_head(page) != head_page)) {
-		bad_page(page, "compound_head not consistent", 0);
-		goto out;
-	}
-	ret = 0;
-out:
-	page->mapping = NULL;
-	clear_compound_head(page);
-	return ret;
-}
-
 static void __meminit __init_single_page(struct page *page, unsigned long pfn,
 				unsigned long zone, int nid)
 {
@@ -1022,51 +1231,13 @@ void __meminit reserve_bootmem_region(unsigned long start, unsigned long end)
 	}
 }
 
-static bool free_pages_prepare(struct page *page, unsigned int order)
-{
-	bool compound = PageCompound(page);
-	int i, bad = 0;
-
-	VM_BUG_ON_PAGE(PageTail(page), page);
-	VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
-
-	trace_mm_page_free(page, order);
-	kmemcheck_free_shadow(page, order);
-	kasan_free_pages(page, order);
-
-	if (PageAnon(page))
-		page->mapping = NULL;
-	bad += free_pages_check(page);
-	for (i = 1; i < (1 << order); i++) {
-		if (compound)
-			bad += free_tail_pages_check(page, page + i);
-		bad += free_pages_check(page + i);
-	}
-	if (bad)
-		return false;
-
-	reset_page_owner(page, order);
-
-	if (!PageHighMem(page)) {
-		debug_check_no_locks_freed(page_address(page),
-					   PAGE_SIZE << order);
-		debug_check_no_obj_freed(page_address(page),
-					   PAGE_SIZE << order);
-	}
-	arch_free_page(page, order);
-	kernel_poison_pages(page, 1 << order, 0);
-	kernel_map_pages(page, 1 << order, 0);
-
-	return true;
-}
-
 static void __free_pages_ok(struct page *page, unsigned int order)
 {
 	unsigned long flags;
 	int migratetype;
 	unsigned long pfn = page_to_pfn(page);
 
-	if (!free_pages_prepare(page, order))
+	if (!free_pages_prepare(page, order, true))
 		return;
 
 	migratetype = get_pfnblock_migratetype(page, pfn);
@@ -1076,8 +1247,7 @@ static void __free_pages_ok(struct page *page, unsigned int order)
 	local_irq_restore(flags);
 }
 
-static void __init __free_pages_boot_core(struct page *page,
-					unsigned long pfn, unsigned int order)
+static void __init __free_pages_boot_core(struct page *page, unsigned int order)
 {
 	unsigned int nr_pages = 1 << order;
 	struct page *p = page;
@@ -1154,7 +1324,7 @@ void __init __free_pages_bootmem(struct page *page, unsigned long pfn,
 {
 	if (early_page_uninitialised(pfn))
 		return;
-	return __free_pages_boot_core(page, pfn, order);
+	return __free_pages_boot_core(page, order);
 }
 
 /*
@@ -1239,12 +1409,12 @@ static void __init deferred_free_range(struct page *page,
 	if (nr_pages == MAX_ORDER_NR_PAGES &&
 	    (pfn & (MAX_ORDER_NR_PAGES-1)) == 0) {
 		set_pageblock_migratetype(page, MIGRATE_MOVABLE);
-		__free_pages_boot_core(page, pfn, MAX_ORDER-1);
+		__free_pages_boot_core(page, MAX_ORDER-1);
 		return;
 	}
 
-	for (i = 0; i < nr_pages; i++, page++, pfn++)
-		__free_pages_boot_core(page, pfn, 0);
+	for (i = 0; i < nr_pages; i++, page++)
+		__free_pages_boot_core(page, 0);
 }
 
 /* Completion tracking for deferred_init_memmap() threads */
@@ -1477,10 +1647,7 @@ static inline void expand(struct zone *zone, struct page *page,
 	}
 }
 
-/*
- * This page is about to be returned from the page allocator
- */
-static inline int check_new_page(struct page *page)
+static void check_new_page_bad(struct page *page)
 {
 	const char *bad_reason = NULL;
 	unsigned long bad_flags = 0;
@@ -1503,11 +1670,20 @@ static inline int check_new_page(struct page *page)
 	if (unlikely(page->mem_cgroup))
 		bad_reason = "page still charged to cgroup";
 #endif
-	if (unlikely(bad_reason)) {
-		bad_page(page, bad_reason, bad_flags);
-		return 1;
-	}
-	return 0;
+	bad_page(page, bad_reason, bad_flags);
+}
+
+/*
+ * This page is about to be returned from the page allocator
+ */
+static inline int check_new_page(struct page *page)
+{
+	if (likely(page_expected_state(page,
+				PAGE_FLAGS_CHECK_AT_PREP|__PG_HWPOISON)))
+		return 0;
+
+	check_new_page_bad(page);
+	return 1;
 }
 
 static inline bool free_pages_prezeroed(bool poisoned)
@@ -1516,16 +1692,48 @@ static inline bool free_pages_prezeroed(bool poisoned)
 		page_poisoning_enabled() && poisoned;
 }
 
-static int prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags,
-								int alloc_flags)
+#ifdef CONFIG_DEBUG_VM
+static bool check_pcp_refill(struct page *page)
+{
+	return false;
+}
+
+static bool check_new_pcp(struct page *page)
+{
+	return check_new_page(page);
+}
+#else
+static bool check_pcp_refill(struct page *page)
+{
+	return check_new_page(page);
+}
+static bool check_new_pcp(struct page *page)
+{
+	return false;
+}
+#endif /* CONFIG_DEBUG_VM */
+
+static bool check_new_pages(struct page *page, unsigned int order)
+{
+	int i;
+	for (i = 0; i < (1 << order); i++) {
+		struct page *p = page + i;
+
+		if (unlikely(check_new_page(p)))
+			return true;
+	}
+
+	return false;
+}
+
+static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags,
+							unsigned int alloc_flags)
 {
 	int i;
 	bool poisoned = true;
 
 	for (i = 0; i < (1 << order); i++) {
 		struct page *p = page + i;
-		if (unlikely(check_new_page(p)))
-			return 1;
 		if (poisoned)
 			poisoned &= page_is_poisoned(p);
 	}
@@ -1557,8 +1765,6 @@ static int prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags,
 		set_page_pfmemalloc(page);
 	else
 		clear_page_pfmemalloc(page);
-
-	return 0;
 }
 
 /*
@@ -1980,6 +2186,9 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
 		if (unlikely(page == NULL))
 			break;
 
+		if (unlikely(check_pcp_refill(page)))
+			continue;
+
 		/*
 		 * Split buddy pages returned by expand() are received here
 		 * in physical page order. The page is added to the callers and
@@ -2157,6 +2366,10 @@ void mark_free_pages(struct zone *zone)
 	for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
 		if (pfn_valid(pfn)) {
 			page = pfn_to_page(pfn);
+
+			if (page_zone(page) != zone)
+				continue;
+
 			if (!swsusp_page_is_forbidden(page))
 				swsusp_unset_page_free(page);
 		}
@@ -2187,7 +2400,7 @@ void free_hot_cold_page(struct page *page, bool cold)
 	unsigned long pfn = page_to_pfn(page);
 	int migratetype;
 
-	if (!free_pages_prepare(page, 0))
+	if (!free_pcp_prepare(page))
 		return;
 
 	migratetype = get_pfnblock_migratetype(page, pfn);
@@ -2343,12 +2556,44 @@ int split_free_page(struct page *page)
 }
 
 /*
+ * Update NUMA hit/miss statistics
+ *
+ * Must be called with interrupts disabled.
+ *
+ * When __GFP_OTHER_NODE is set assume the node of the preferred
+ * zone is the local node. This is useful for daemons who allocate
+ * memory on behalf of other processes.
+ */
+static inline void zone_statistics(struct zone *preferred_zone, struct zone *z,
+								gfp_t flags)
+{
+#ifdef CONFIG_NUMA
+	int local_nid = numa_node_id();
+	enum zone_stat_item local_stat = NUMA_LOCAL;
+
+	if (unlikely(flags & __GFP_OTHER_NODE)) {
+		local_stat = NUMA_OTHER;
+		local_nid = preferred_zone->node;
+	}
+
+	if (z->node == local_nid) {
+		__inc_zone_state(z, NUMA_HIT);
+		__inc_zone_state(z, local_stat);
+	} else {
+		__inc_zone_state(z, NUMA_MISS);
+		__inc_zone_state(preferred_zone, NUMA_FOREIGN);
+	}
+#endif
+}
+
+/*
  * Allocate a page from the given zone. Use pcplists for order-0 allocations.
  */
 static inline
 struct page *buffered_rmqueue(struct zone *preferred_zone,
 			struct zone *zone, unsigned int order,
-			gfp_t gfp_flags, int alloc_flags, int migratetype)
+			gfp_t gfp_flags, unsigned int alloc_flags,
+			int migratetype)
 {
 	unsigned long flags;
 	struct page *page;
@@ -2359,21 +2604,24 @@ struct page *buffered_rmqueue(struct zone *preferred_zone,
 		struct list_head *list;
 
 		local_irq_save(flags);
-		pcp = &this_cpu_ptr(zone->pageset)->pcp;
-		list = &pcp->lists[migratetype];
-		if (list_empty(list)) {
-			pcp->count += rmqueue_bulk(zone, 0,
-					pcp->batch, list,
-					migratetype, cold);
-			if (unlikely(list_empty(list)))
-				goto failed;
-		}
+		do {
+			pcp = &this_cpu_ptr(zone->pageset)->pcp;
+			list = &pcp->lists[migratetype];
+			if (list_empty(list)) {
+				pcp->count += rmqueue_bulk(zone, 0,
+						pcp->batch, list,
+						migratetype, cold);
+				if (unlikely(list_empty(list)))
+					goto failed;
+			}
 
-		if (cold)
-			page = list_last_entry(list, struct page, lru);
-		else
-			page = list_first_entry(list, struct page, lru);
+			if (cold)
+				page = list_last_entry(list, struct page, lru);
+			else
+				page = list_first_entry(list, struct page, lru);
+		} while (page && check_new_pcp(page));
 
+		__dec_zone_state(zone, NR_ALLOC_BATCH);
 		list_del(&page->lru);
 		pcp->count--;
 	} else {
@@ -2384,22 +2632,24 @@ struct page *buffered_rmqueue(struct zone *preferred_zone,
 		WARN_ON_ONCE((gfp_flags & __GFP_NOFAIL) && (order > 1));
 		spin_lock_irqsave(&zone->lock, flags);
 
-		page = NULL;
-		if (alloc_flags & ALLOC_HARDER) {
-			page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC);
-			if (page)
-				trace_mm_page_alloc_zone_locked(page, order, migratetype);
-		}
-		if (!page)
-			page = __rmqueue(zone, order, migratetype);
+		do {
+			page = NULL;
+			if (alloc_flags & ALLOC_HARDER) {
+				page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC);
+				if (page)
+					trace_mm_page_alloc_zone_locked(page, order, migratetype);
+			}
+			if (!page)
+				page = __rmqueue(zone, order, migratetype);
+		} while (page && check_new_pages(page, order));
 		spin_unlock(&zone->lock);
 		if (!page)
 			goto failed;
+		__mod_zone_page_state(zone, NR_ALLOC_BATCH, -(1 << order));
 		__mod_zone_freepage_state(zone, -(1 << order),
 					  get_pcppage_migratetype(page));
 	}
 
-	__mod_zone_page_state(zone, NR_ALLOC_BATCH, -(1 << order));
 	if (atomic_long_read(&zone->vm_stat[NR_ALLOC_BATCH]) <= 0 &&
 	    !test_bit(ZONE_FAIR_DEPLETED, &zone->flags))
 		set_bit(ZONE_FAIR_DEPLETED, &zone->flags);
@@ -2501,12 +2751,13 @@ static inline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
  * to check in the allocation paths if no pages are free.
  */
 static bool __zone_watermark_ok(struct zone *z, unsigned int order,
-			unsigned long mark, int classzone_idx, int alloc_flags,
+			unsigned long mark, int classzone_idx,
+			unsigned int alloc_flags,
 			long free_pages)
 {
 	long min = mark;
 	int o;
-	const int alloc_harder = (alloc_flags & ALLOC_HARDER);
+	const bool alloc_harder = (alloc_flags & ALLOC_HARDER);
 
 	/* free_pages may go negative - that's OK */
 	free_pages -= (1 << order) - 1;
@@ -2569,12 +2820,38 @@ static bool __zone_watermark_ok(struct zone *z, unsigned int order,
 }
 
 bool zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark,
-		      int classzone_idx, int alloc_flags)
+		      int classzone_idx, unsigned int alloc_flags)
 {
 	return __zone_watermark_ok(z, order, mark, classzone_idx, alloc_flags,
 					zone_page_state(z, NR_FREE_PAGES));
 }
 
+static inline bool zone_watermark_fast(struct zone *z, unsigned int order,
+		unsigned long mark, int classzone_idx, unsigned int alloc_flags)
+{
+	long free_pages = zone_page_state(z, NR_FREE_PAGES);
+	long cma_pages = 0;
+
+#ifdef CONFIG_CMA
+	/* If allocation can't use CMA areas don't use free CMA pages */
+	if (!(alloc_flags & ALLOC_CMA))
+		cma_pages = zone_page_state(z, NR_FREE_CMA_PAGES);
+#endif
+
+	/*
+	 * Fast check for order-0 only. If this fails then the reserves
+	 * need to be calculated. There is a corner case where the check
+	 * passes but only the high-order atomic reserve are free. If
+	 * the caller is !atomic then it'll uselessly search the free
+	 * list. That corner case is then slower but it is harmless.
+	 */
+	if (!order && (free_pages - cma_pages) > mark + z->lowmem_reserve[classzone_idx])
+		return true;
+
+	return __zone_watermark_ok(z, order, mark, classzone_idx, alloc_flags,
+					free_pages);
+}
+
 bool zone_watermark_ok_safe(struct zone *z, unsigned int order,
 			unsigned long mark, int classzone_idx)
 {
@@ -2630,27 +2907,24 @@ static struct page *
 get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
 						const struct alloc_context *ac)
 {
-	struct zonelist *zonelist = ac->zonelist;
-	struct zoneref *z;
-	struct page *page = NULL;
+	struct zoneref *z = ac->preferred_zoneref;
 	struct zone *zone;
-	int nr_fair_skipped = 0;
-	bool zonelist_rescan;
+	bool fair_skipped = false;
+	bool apply_fair = (alloc_flags & ALLOC_FAIR);
 
 zonelist_scan:
-	zonelist_rescan = false;
-
 	/*
 	 * Scan zonelist, looking for a zone with enough free.
 	 * See also __cpuset_node_allowed() comment in kernel/cpuset.c.
 	 */
-	for_each_zone_zonelist_nodemask(zone, z, zonelist, ac->high_zoneidx,
+	for_next_zone_zonelist_nodemask(zone, z, ac->zonelist, ac->high_zoneidx,
 								ac->nodemask) {
+		struct page *page;
 		unsigned long mark;
 
 		if (cpusets_enabled() &&
 			(alloc_flags & ALLOC_CPUSET) &&
-			!cpuset_zone_allowed(zone, gfp_mask))
+			!__cpuset_zone_allowed(zone, gfp_mask))
 				continue;
 		/*
 		 * Distribute pages in proportion to the individual
@@ -2658,13 +2932,16 @@ zonelist_scan:
 		 * page was allocated in should have no effect on the
 		 * time the page has in memory before being reclaimed.
 		 */
-		if (alloc_flags & ALLOC_FAIR) {
-			if (!zone_local(ac->preferred_zone, zone))
-				break;
+		if (apply_fair) {
 			if (test_bit(ZONE_FAIR_DEPLETED, &zone->flags)) {
-				nr_fair_skipped++;
+				fair_skipped = true;
 				continue;
 			}
+			if (!zone_local(ac->preferred_zoneref->zone, zone)) {
+				if (fair_skipped)
+					goto reset_fair;
+				apply_fair = false;
+			}
 		}
 		/*
 		 * When allocating a page cache page for writing, we
@@ -2696,8 +2973,8 @@ zonelist_scan:
 			continue;
 
 		mark = zone->watermark[alloc_flags & ALLOC_WMARK_MASK];
-		if (!zone_watermark_ok(zone, order, mark,
-				       ac->classzone_idx, alloc_flags)) {
+		if (!zone_watermark_fast(zone, order, mark,
+				       ac_classzone_idx(ac), alloc_flags)) {
 			int ret;
 
 			/* Checked here to keep the fast path fast */
@@ -2706,7 +2983,7 @@ zonelist_scan:
 				goto try_this_zone;
 
 			if (zone_reclaim_mode == 0 ||
-			    !zone_allows_reclaim(ac->preferred_zone, zone))
+			    !zone_allows_reclaim(ac->preferred_zoneref->zone, zone))
 				continue;
 
 			ret = zone_reclaim(zone, gfp_mask, order);
@@ -2720,7 +2997,7 @@ zonelist_scan:
 			default:
 				/* did we reclaim enough */
 				if (zone_watermark_ok(zone, order, mark,
-						ac->classzone_idx, alloc_flags))
+						ac_classzone_idx(ac), alloc_flags))
 					goto try_this_zone;
 
 				continue;
@@ -2728,11 +3005,10 @@ zonelist_scan:
 		}
 
 try_this_zone:
-		page = buffered_rmqueue(ac->preferred_zone, zone, order,
+		page = buffered_rmqueue(ac->preferred_zoneref->zone, zone, order,
 				gfp_mask, alloc_flags, ac->migratetype);
 		if (page) {
-			if (prep_new_page(page, order, gfp_mask, alloc_flags))
-				goto try_this_zone;
+			prep_new_page(page, order, gfp_mask, alloc_flags);
 
 			/*
 			 * If this is a high-order atomic allocation then check
@@ -2753,18 +3029,13 @@ try_this_zone:
 	 * include remote zones now, before entering the slowpath and waking
 	 * kswapd: prefer spilling to a remote zone over swapping locally.
 	 */
-	if (alloc_flags & ALLOC_FAIR) {
-		alloc_flags &= ~ALLOC_FAIR;
-		if (nr_fair_skipped) {
-			zonelist_rescan = true;
-			reset_alloc_batches(ac->preferred_zone);
-		}
-		if (nr_online_nodes > 1)
-			zonelist_rescan = true;
-	}
-
-	if (zonelist_rescan)
+	if (fair_skipped) {
+reset_fair:
+		apply_fair = false;
+		fair_skipped = false;
+		reset_alloc_batches(ac->preferred_zoneref->zone);
 		goto zonelist_scan;
+	}
 
 	return NULL;
 }
@@ -2872,22 +3143,18 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
 		/* The OOM killer does not needlessly kill tasks for lowmem */
 		if (ac->high_zoneidx < ZONE_NORMAL)
 			goto out;
-		/* The OOM killer does not compensate for IO-less reclaim */
-		if (!(gfp_mask & __GFP_FS)) {
-			/*
-			 * XXX: Page reclaim didn't yield anything,
-			 * and the OOM killer can't be invoked, but
-			 * keep looping as per tradition.
-			 *
-			 * But do not keep looping if oom_killer_disable()
-			 * was already called, for the system is trying to
-			 * enter a quiescent state during suspend.
-			 */
-			*did_some_progress = !oom_killer_disabled;
-			goto out;
-		}
 		if (pm_suspended_storage())
 			goto out;
+		/*
+		 * XXX: GFP_NOFS allocations should rather fail than rely on
+		 * other request to make a forward progress.
+		 * We are in an unfortunate situation where out_of_memory cannot
+		 * do much for this context but let's try it to at least get
+		 * access to memory reserved if the current task is killed (see
+		 * out_of_memory). Once filesystems are ready to handle allocation
+		 * failures more gracefully we should just bail out here.
+		 */
+
 		/* The OOM killer may not free memory on a specific node */
 		if (gfp_mask & __GFP_THISNODE)
 			goto out;
@@ -2917,7 +3184,7 @@ out:
 /* Try memory compaction for high-order allocations before reclaim */
 static struct page *
 __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
-		int alloc_flags, const struct alloc_context *ac,
+		unsigned int alloc_flags, const struct alloc_context *ac,
 		enum migrate_mode mode, int *contended_compaction,
 		bool *deferred_compaction)
 {
@@ -2973,7 +3240,7 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
 #else
 static inline struct page *
 __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
-		int alloc_flags, const struct alloc_context *ac,
+		unsigned int alloc_flags, const struct alloc_context *ac,
 		enum migrate_mode mode, int *contended_compaction,
 		bool *deferred_compaction)
 {
@@ -3013,7 +3280,7 @@ __perform_reclaim(gfp_t gfp_mask, unsigned int order,
 /* The really slow allocator path where we enter direct reclaim */
 static inline struct page *
 __alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order,
-		int alloc_flags, const struct alloc_context *ac,
+		unsigned int alloc_flags, const struct alloc_context *ac,
 		unsigned long *did_some_progress)
 {
 	struct page *page = NULL;
@@ -3049,13 +3316,13 @@ static void wake_all_kswapds(unsigned int order, const struct alloc_context *ac)
 
 	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist,
 						ac->high_zoneidx, ac->nodemask)
-		wakeup_kswapd(zone, order, zone_idx(ac->preferred_zone));
+		wakeup_kswapd(zone, order, ac_classzone_idx(ac));
 }
 
-static inline int
+static inline unsigned int
 gfp_to_alloc_flags(gfp_t gfp_mask)
 {
-	int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET;
+	unsigned int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET;
 
 	/* __GFP_HIGH is assumed to be the same as ALLOC_HIGH to save a branch. */
 	BUILD_BUG_ON(__GFP_HIGH != (__force gfp_t) ALLOC_HIGH);
@@ -3116,7 +3383,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 {
 	bool can_direct_reclaim = gfp_mask & __GFP_DIRECT_RECLAIM;
 	struct page *page = NULL;
-	int alloc_flags;
+	unsigned int alloc_flags;
 	unsigned long pages_reclaimed = 0;
 	unsigned long did_some_progress;
 	enum migrate_mode migration_mode = MIGRATE_ASYNC;
@@ -3153,17 +3420,6 @@ retry:
 	 */
 	alloc_flags = gfp_to_alloc_flags(gfp_mask);
 
-	/*
-	 * Find the true preferred zone if the allocation is unconstrained by
-	 * cpusets.
-	 */
-	if (!(alloc_flags & ALLOC_CPUSET) && !ac->nodemask) {
-		struct zoneref *preferred_zoneref;
-		preferred_zoneref = first_zones_zonelist(ac->zonelist,
-				ac->high_zoneidx, NULL, &ac->preferred_zone);
-		ac->classzone_idx = zonelist_zone_idx(preferred_zoneref);
-	}
-
 	/* This is the last chance, in general, before the goto nopage. */
 	page = get_page_from_freelist(gfp_mask, order,
 				alloc_flags & ~ALLOC_NO_WATERMARKS, ac);
@@ -3278,7 +3534,7 @@ retry:
 	if ((did_some_progress && order <= PAGE_ALLOC_COSTLY_ORDER) ||
 	    ((gfp_mask & __GFP_REPEAT) && pages_reclaimed < (1 << order))) {
 		/* Wait for some write requests to complete then retry */
-		wait_iff_congested(ac->preferred_zone, BLK_RW_ASYNC, HZ/50);
+		wait_iff_congested(ac->preferred_zoneref->zone, BLK_RW_ASYNC, HZ/50);
 		goto retry;
 	}
 
@@ -3316,17 +3572,24 @@ struct page *
 __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
 			struct zonelist *zonelist, nodemask_t *nodemask)
 {
-	struct zoneref *preferred_zoneref;
-	struct page *page = NULL;
+	struct page *page;
 	unsigned int cpuset_mems_cookie;
-	int alloc_flags = ALLOC_WMARK_LOW|ALLOC_CPUSET|ALLOC_FAIR;
-	gfp_t alloc_mask; /* The gfp_t that was actually used for allocation */
+	unsigned int alloc_flags = ALLOC_WMARK_LOW|ALLOC_FAIR;
+	gfp_t alloc_mask = gfp_mask; /* The gfp_t that was actually used for allocation */
 	struct alloc_context ac = {
 		.high_zoneidx = gfp_zone(gfp_mask),
+		.zonelist = zonelist,
 		.nodemask = nodemask,
 		.migratetype = gfpflags_to_migratetype(gfp_mask),
 	};
 
+	if (cpusets_enabled()) {
+		alloc_mask |= __GFP_HARDWALL;
+		alloc_flags |= ALLOC_CPUSET;
+		if (!ac.nodemask)
+			ac.nodemask = &cpuset_current_mems_allowed;
+	}
+
 	gfp_mask &= gfp_allowed_mask;
 
 	lockdep_trace_alloc(gfp_mask);
@@ -3350,49 +3613,54 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
 retry_cpuset:
 	cpuset_mems_cookie = read_mems_allowed_begin();
 
-	/* We set it here, as __alloc_pages_slowpath might have changed it */
-	ac.zonelist = zonelist;
-
 	/* Dirty zone balancing only done in the fast path */
 	ac.spread_dirty_pages = (gfp_mask & __GFP_WRITE);
 
 	/* The preferred zone is used for statistics later */
-	preferred_zoneref = first_zones_zonelist(ac.zonelist, ac.high_zoneidx,
-				ac.nodemask ? : &cpuset_current_mems_allowed,
-				&ac.preferred_zone);
-	if (!ac.preferred_zone)
-		goto out;
-	ac.classzone_idx = zonelist_zone_idx(preferred_zoneref);
+	ac.preferred_zoneref = first_zones_zonelist(ac.zonelist,
+					ac.high_zoneidx, ac.nodemask);
+	if (!ac.preferred_zoneref) {
+		page = NULL;
+		goto no_zone;
+	}
 
 	/* First allocation attempt */
-	alloc_mask = gfp_mask|__GFP_HARDWALL;
 	page = get_page_from_freelist(alloc_mask, order, alloc_flags, &ac);
-	if (unlikely(!page)) {
-		/*
-		 * Runtime PM, block IO and its error handling path
-		 * can deadlock because I/O on the device might not
-		 * complete.
-		 */
-		alloc_mask = memalloc_noio_flags(gfp_mask);
-		ac.spread_dirty_pages = false;
-
-		page = __alloc_pages_slowpath(alloc_mask, order, &ac);
-	}
+	if (likely(page))
+		goto out;
 
-	if (kmemcheck_enabled && page)
-		kmemcheck_pagealloc_alloc(page, order, gfp_mask);
+	/*
+	 * Runtime PM, block IO and its error handling path can deadlock
+	 * because I/O on the device might not complete.
+	 */
+	alloc_mask = memalloc_noio_flags(gfp_mask);
+	ac.spread_dirty_pages = false;
 
-	trace_mm_page_alloc(page, order, alloc_mask, ac.migratetype);
+	/*
+	 * Restore the original nodemask if it was potentially replaced with
+	 * &cpuset_current_mems_allowed to optimize the fast-path attempt.
+	 */
+	if (cpusets_enabled())
+		ac.nodemask = nodemask;
+	page = __alloc_pages_slowpath(alloc_mask, order, &ac);
 
-out:
+no_zone:
 	/*
 	 * When updating a task's mems_allowed, it is possible to race with
 	 * parallel threads in such a way that an allocation can fail while
 	 * the mask is being updated. If a page allocation is about to fail,
 	 * check if the cpuset changed during allocation and if so, retry.
 	 */
-	if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
+	if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie))) {
+		alloc_mask = gfp_mask;
 		goto retry_cpuset;
+	}
+
+out:
+	if (kmemcheck_enabled && page)
+		kmemcheck_pagealloc_alloc(page, order, gfp_mask);
+
+	trace_mm_page_alloc(page, order, alloc_mask, ac.migratetype);
 
 	return page;
 }
@@ -3790,6 +4058,8 @@ void si_meminfo_node(struct sysinfo *val, int nid)
 {
 	int zone_type;		/* needs to be signed */
 	unsigned long managed_pages = 0;
+	unsigned long managed_highpages = 0;
+	unsigned long free_highpages = 0;
 	pg_data_t *pgdat = NODE_DATA(nid);
 
 	for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++)
@@ -3798,12 +4068,19 @@ void si_meminfo_node(struct sysinfo *val, int nid)
 	val->sharedram = node_page_state(nid, NR_SHMEM);
 	val->freeram = node_page_state(nid, NR_FREE_PAGES);
 #ifdef CONFIG_HIGHMEM
-	val->totalhigh = pgdat->node_zones[ZONE_HIGHMEM].managed_pages;
-	val->freehigh = zone_page_state(&pgdat->node_zones[ZONE_HIGHMEM],
-			NR_FREE_PAGES);
+	for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++) {
+		struct zone *zone = &pgdat->node_zones[zone_type];
+
+		if (is_highmem(zone)) {
+			managed_highpages += zone->managed_pages;
+			free_highpages += zone_page_state(zone, NR_FREE_PAGES);
+		}
+	}
+	val->totalhigh = managed_highpages;
+	val->freehigh = free_highpages;
 #else
-	val->totalhigh = 0;
-	val->freehigh = 0;
+	val->totalhigh = managed_highpages;
+	val->freehigh = free_highpages;
 #endif
 	val->mem_unit = PAGE_SIZE;
 }
@@ -4390,13 +4667,12 @@ static void build_zonelists(pg_data_t *pgdat)
  */
 int local_memory_node(int node)
 {
-	struct zone *zone;
+	struct zoneref *z;
 
-	(void)first_zones_zonelist(node_zonelist(node, GFP_KERNEL),
+	z = first_zones_zonelist(node_zonelist(node, GFP_KERNEL),
 				   gfp_zone(GFP_KERNEL),
-				   NULL,
-				   &zone);
-	return zone->node;
+				   NULL);
+	return z->zone->node;
 }
 #endif
 
@@ -6725,98 +7001,6 @@ void *__init alloc_large_system_hash(const char *tablename,
 	return table;
 }
 
-/* Return a pointer to the bitmap storing bits affecting a block of pages */
-static inline unsigned long *get_pageblock_bitmap(struct zone *zone,
-							unsigned long pfn)
-{
-#ifdef CONFIG_SPARSEMEM
-	return __pfn_to_section(pfn)->pageblock_flags;
-#else
-	return zone->pageblock_flags;
-#endif /* CONFIG_SPARSEMEM */
-}
-
-static inline int pfn_to_bitidx(struct zone *zone, unsigned long pfn)
-{
-#ifdef CONFIG_SPARSEMEM
-	pfn &= (PAGES_PER_SECTION-1);
-	return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
-#else
-	pfn = pfn - round_down(zone->zone_start_pfn, pageblock_nr_pages);
-	return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
-#endif /* CONFIG_SPARSEMEM */
-}
-
-/**
- * get_pfnblock_flags_mask - Return the requested group of flags for the pageblock_nr_pages block of pages
- * @page: The page within the block of interest
- * @pfn: The target page frame number
- * @end_bitidx: The last bit of interest to retrieve
- * @mask: mask of bits that the caller is interested in
- *
- * Return: pageblock_bits flags
- */
-unsigned long get_pfnblock_flags_mask(struct page *page, unsigned long pfn,
-					unsigned long end_bitidx,
-					unsigned long mask)
-{
-	struct zone *zone;
-	unsigned long *bitmap;
-	unsigned long bitidx, word_bitidx;
-	unsigned long word;
-
-	zone = page_zone(page);
-	bitmap = get_pageblock_bitmap(zone, pfn);
-	bitidx = pfn_to_bitidx(zone, pfn);
-	word_bitidx = bitidx / BITS_PER_LONG;
-	bitidx &= (BITS_PER_LONG-1);
-
-	word = bitmap[word_bitidx];
-	bitidx += end_bitidx;
-	return (word >> (BITS_PER_LONG - bitidx - 1)) & mask;
-}
-
-/**
- * set_pfnblock_flags_mask - Set the requested group of flags for a pageblock_nr_pages block of pages
- * @page: The page within the block of interest
- * @flags: The flags to set
- * @pfn: The target page frame number
- * @end_bitidx: The last bit of interest
- * @mask: mask of bits that the caller is interested in
- */
-void set_pfnblock_flags_mask(struct page *page, unsigned long flags,
-					unsigned long pfn,
-					unsigned long end_bitidx,
-					unsigned long mask)
-{
-	struct zone *zone;
-	unsigned long *bitmap;
-	unsigned long bitidx, word_bitidx;
-	unsigned long old_word, word;
-
-	BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4);
-
-	zone = page_zone(page);
-	bitmap = get_pageblock_bitmap(zone, pfn);
-	bitidx = pfn_to_bitidx(zone, pfn);
-	word_bitidx = bitidx / BITS_PER_LONG;
-	bitidx &= (BITS_PER_LONG-1);
-
-	VM_BUG_ON_PAGE(!zone_spans_pfn(zone, pfn), page);
-
-	bitidx += end_bitidx;
-	mask <<= (BITS_PER_LONG - bitidx - 1);
-	flags <<= (BITS_PER_LONG - bitidx - 1);
-
-	word = READ_ONCE(bitmap[word_bitidx]);
-	for (;;) {
-		old_word = cmpxchg(&bitmap[word_bitidx], word, (word & ~mask) | flags);
-		if (word == old_word)
-			break;
-		word = old_word;
-	}
-}
-
 /*
  * This function checks whether pageblock includes unmovable pages or not.
  * If @count is not zero, it is okay to include less @count unmovable pages
@@ -6864,7 +7048,7 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
 		 * We can't use page_count without pin a page
 		 * because another CPU can free compound page.
 		 * This check already skips compound tails of THP
-		 * because their page->_count is zero at all time.
+		 * because their page->_refcount is zero at all time.
 		 */
 		if (!page_ref_count(page)) {
 			if (PageBuddy(page))
@@ -7177,7 +7361,8 @@ void zone_pcp_reset(struct zone *zone)
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
 /*
- * All pages in the range must be isolated before calling this.
+ * All pages in the range must be in a single zone and isolated
+ * before calling this.
  */
 void
 __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)