Merge c4386bd8ee ("mm/memremap: add ZONE_DEVICE support for compound pages") into android-mainline

Steps on the way to 5.17-rc1

Resolves merge conflicts with:
	mm/memremap.c

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I506780b8aa65e17a84fd9adb748e16825a3f4833

include/linux/memremap.h

@@ -88,6 +88,11 @@ struct dev_pagemap_ops {
  * @done: completion for @ref
  * @type: memory type: see MEMORY_* in memory_hotplug.h
  * @flags: PGMAP_* flags to specify defailed behavior
+ * @vmemmap_shift: structural definition of how the vmemmap page metadata
+ *      is populated, specifically the metadata page order.
+ *	A zero value (default) uses base pages as the vmemmap metadata
+ *	representation. A bigger value will set up compound struct pages
+ *	of the requested order value.
  * @ops: method table
  * @owner: an opaque pointer identifying the entity that manages this
  *	instance.  Used by various helpers to make sure that no
@@ -102,6 +107,7 @@ struct dev_pagemap {
 	struct completion done;
 	enum memory_type type;
 	unsigned int flags;
+	unsigned long vmemmap_shift;
 	const struct dev_pagemap_ops *ops;
 	void *owner;
 	int nr_range;
@@ -118,6 +124,11 @@ static inline struct vmem_altmap *pgmap_altmap(struct dev_pagemap *pgmap)
 	return NULL;
 }
 
+static inline unsigned long pgmap_vmemmap_nr(struct dev_pagemap *pgmap)
+{
+	return 1 << pgmap->vmemmap_shift;
+}
+
 #ifdef CONFIG_ZONE_DEVICE
 void *memremap_pages(struct dev_pagemap *pgmap, int nid);
 void memunmap_pages(struct dev_pagemap *pgmap);

mm/memremap.c

@@ -102,15 +102,22 @@ static unsigned long pfn_end(struct dev_pagemap *pgmap, int range_id)
 	return (range->start + range_len(range)) >> PAGE_SHIFT;
 }
 
-static unsigned long pfn_next(unsigned long pfn)
+static unsigned long pfn_next(struct dev_pagemap *pgmap, unsigned long pfn)
 {
-	if (pfn % 1024 == 0)
+	if (pfn % (1024 << pgmap->vmemmap_shift))
 		cond_resched();
-	return pfn + 1;
+	return pfn + pgmap_vmemmap_nr(pgmap);
+}
+
+static unsigned long pfn_len(struct dev_pagemap *pgmap, unsigned long range_id)
+{
+	return (pfn_end(pgmap, range_id) -
+		pfn_first(pgmap, range_id)) >> pgmap->vmemmap_shift;
 }
 
 #define for_each_device_pfn(pfn, map, i) \
-	for (pfn = pfn_first(map, i); pfn < pfn_end(map, i); pfn = pfn_next(pfn))
+	for (pfn = pfn_first(map, i); pfn < pfn_end(map, i); \
+	     pfn = pfn_next(map, pfn))
 
 static void pageunmap_range(struct dev_pagemap *pgmap, int range_id)
 {
@@ -271,8 +278,7 @@ static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params,
 	memmap_init_zone_device(&NODE_DATA(nid)->node_zones[ZONE_DEVICE],
 				PHYS_PFN(range->start),
 				PHYS_PFN(range_len(range)), pgmap);
-	percpu_ref_get_many(&pgmap->ref,
-		pfn_end(pgmap, range_id) - pfn_first(pgmap, range_id));
+	percpu_ref_get_many(&pgmap->ref, pfn_len(pgmap, range_id));
 	return 0;
 
 err_add_memory:

mm/page_alloc.c

@@ -6612,6 +6612,35 @@ static void __ref __init_zone_device_page(struct page *page, unsigned long pfn,
 	}
 }
 
+static void __ref memmap_init_compound(struct page *head,
+				       unsigned long head_pfn,
+				       unsigned long zone_idx, int nid,
+				       struct dev_pagemap *pgmap,
+				       unsigned long nr_pages)
+{
+	unsigned long pfn, end_pfn = head_pfn + nr_pages;
+	unsigned int order = pgmap->vmemmap_shift;
+
+	__SetPageHead(head);
+	for (pfn = head_pfn + 1; pfn < end_pfn; pfn++) {
+		struct page *page = pfn_to_page(pfn);
+
+		__init_zone_device_page(page, pfn, zone_idx, nid, pgmap);
+		prep_compound_tail(head, pfn - head_pfn);
+		set_page_count(page, 0);
+
+		/*
+		 * The first tail page stores compound_mapcount_ptr() and
+		 * compound_order() and the second tail page stores
+		 * compound_pincount_ptr(). Call prep_compound_head() after
+		 * the first and second tail pages have been initialized to
+		 * not have the data overwritten.
+		 */
+		if (pfn == head_pfn + 2)
+			prep_compound_head(head, order);
+	}
+}
+
 void __ref memmap_init_zone_device(struct zone *zone,
 				   unsigned long start_pfn,
 				   unsigned long nr_pages,
@@ -6620,6 +6649,7 @@ void __ref memmap_init_zone_device(struct zone *zone,
 	unsigned long pfn, end_pfn = start_pfn + nr_pages;
 	struct pglist_data *pgdat = zone->zone_pgdat;
 	struct vmem_altmap *altmap = pgmap_altmap(pgmap);
+	unsigned int pfns_per_compound = pgmap_vmemmap_nr(pgmap);
 	unsigned long zone_idx = zone_idx(zone);
 	unsigned long start = jiffies;
 	int nid = pgdat->node_id;
@@ -6637,10 +6667,16 @@ void __ref memmap_init_zone_device(struct zone *zone,
 		nr_pages = end_pfn - start_pfn;
 	}
 
-	for (pfn = start_pfn; pfn < end_pfn; pfn++) {
+	for (pfn = start_pfn; pfn < end_pfn; pfn += pfns_per_compound) {
 		struct page *page = pfn_to_page(pfn);
 
 		__init_zone_device_page(page, pfn, zone_idx, nid, pgmap);
+
+		if (pfns_per_compound == 1)
+			continue;
+
+		memmap_init_compound(page, pfn, zone_idx, nid, pgmap,
+				     pfns_per_compound);
 	}
 
 	pr_info("%s initialised %lu pages in %ums\n", __func__,