Hibernate: Take overlapping zones into account (rev. 2)

It has been requested to make hibernation work with memory
hotplugging enabled and for this purpose the hibernation code has to
be reworked to take the possible overlapping of zones into account.
Thus, rework the hibernation memory bitmaps code to prevent
duplication of PFNs from occuring and add checks to make sure that
one page frame will not be marked as saveable many times.

Additionally, use list.h lists instead of open-coded lists to
implement the memory bitmaps.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Len Brown <len.brown@intel.com>

kernel/power/snapshot.c

@@ -25,6 +25,7 @@
 #include <linux/syscalls.h>
 #include <linux/console.h>
 #include <linux/highmem.h>
+#include <linux/list.h>
 
 #include <asm/uaccess.h>
 #include <asm/mmu_context.h>
@@ -192,12 +193,6 @@ static void *chain_alloc(struct chain_allocator *ca, unsigned int size)
 	return ret;
 }
 
-static void chain_free(struct chain_allocator *ca, int clear_page_nosave)
-{
-	free_list_of_pages(ca->chain, clear_page_nosave);
-	memset(ca, 0, sizeof(struct chain_allocator));
-}
-
 /**
  *	Data types related to memory bitmaps.
  *
@@ -233,7 +228,7 @@ static void chain_free(struct chain_allocator *ca, int clear_page_nosave)
 #define BM_BITS_PER_BLOCK	(PAGE_SIZE << 3)
 
 struct bm_block {
-	struct bm_block *next;		/* next element of the list */
+	struct list_head hook;	/* hook into a list of bitmap blocks */
 	unsigned long start_pfn;	/* pfn represented by the first bit */
 	unsigned long end_pfn;	/* pfn represented by the last bit plus 1 */
 	unsigned long *data;	/* bitmap representing pages */
@@ -244,24 +239,15 @@ static inline unsigned long bm_block_bits(struct bm_block *bb)
 	return bb->end_pfn - bb->start_pfn;
 }
 
-struct zone_bitmap {
-	struct zone_bitmap *next;	/* next element of the list */
-	unsigned long start_pfn;	/* minimal pfn in this zone */
-	unsigned long end_pfn;		/* maximal pfn in this zone plus 1 */
-	struct bm_block *bm_blocks;	/* list of bitmap blocks */
-	struct bm_block *cur_block;	/* recently used bitmap block */
-};
-
 /* strcut bm_position is used for browsing memory bitmaps */
 
 struct bm_position {
-	struct zone_bitmap *zone_bm;
 	struct bm_block *block;
 	int bit;
 };
 
 struct memory_bitmap {
-	struct zone_bitmap *zone_bm_list;	/* list of zone bitmaps */
+	struct list_head blocks;	/* list of bitmap blocks */
 	struct linked_page *p_list;	/* list of pages used to store zone
 					 * bitmap objects and bitmap block
 					 * objects
@@ -273,11 +259,7 @@ struct memory_bitmap {
 
 static void memory_bm_position_reset(struct memory_bitmap *bm)
 {
-	struct zone_bitmap *zone_bm;
-
-	zone_bm = bm->zone_bm_list;
-	bm->cur.zone_bm = zone_bm;
-	bm->cur.block = zone_bm->bm_blocks;
+	bm->cur.block = list_entry(bm->blocks.next, struct bm_block, hook);
 	bm->cur.bit = 0;
 }
 
@@ -285,151 +267,184 @@ static void memory_bm_free(struct memory_bitmap *bm, int clear_nosave_free);
 
 /**
  *	create_bm_block_list - create a list of block bitmap objects
+ *	@nr_blocks - number of blocks to allocate
+ *	@list - list to put the allocated blocks into
+ *	@ca - chain allocator to be used for allocating memory
  */
-
-static inline struct bm_block *
-create_bm_block_list(unsigned int nr_blocks, struct chain_allocator *ca)
+static int create_bm_block_list(unsigned long pages,
+				struct list_head *list,
+				struct chain_allocator *ca)
 {
-	struct bm_block *bblist = NULL;
+	unsigned int nr_blocks = DIV_ROUND_UP(pages, BM_BITS_PER_BLOCK);
 
 	while (nr_blocks-- > 0) {
 		struct bm_block *bb;
 
 		bb = chain_alloc(ca, sizeof(struct bm_block));
 		if (!bb)
-			return NULL;
-
-		bb->next = bblist;
-		bblist = bb;
+			return -ENOMEM;
+		list_add(&bb->hook, list);
 	}
-	return bblist;
+
+	return 0;
 }
 
+struct mem_extent {
+	struct list_head hook;
+	unsigned long start;
+	unsigned long end;
+};
+
 /**
- *	create_zone_bm_list - create a list of zone bitmap objects
+ *	free_mem_extents - free a list of memory extents
+ *	@list - list of extents to empty
  */
+static void free_mem_extents(struct list_head *list)
+{
+	struct mem_extent *ext, *aux;
+
+	list_for_each_entry_safe(ext, aux, list, hook) {
+		list_del(&ext->hook);
+		kfree(ext);
+	}
+}
 
-static inline struct zone_bitmap *
-create_zone_bm_list(unsigned int nr_zones, struct chain_allocator *ca)
+/**
+ *	create_mem_extents - create a list of memory extents representing
+ *	                     contiguous ranges of PFNs
+ *	@list - list to put the extents into
+ *	@gfp_mask - mask to use for memory allocations
+ */
+static int create_mem_extents(struct list_head *list, gfp_t gfp_mask)
 {
-	struct zone_bitmap *zbmlist = NULL;
+	struct zone *zone;
 
-	while (nr_zones-- > 0) {
-		struct zone_bitmap *zbm;
+	INIT_LIST_HEAD(list);
 
-		zbm = chain_alloc(ca, sizeof(struct zone_bitmap));
-		if (!zbm)
-			return NULL;
+	for_each_zone(zone) {
+		unsigned long zone_start, zone_end;
+		struct mem_extent *ext, *cur, *aux;
+
+		if (!populated_zone(zone))
+			continue;
+
+		zone_start = zone->zone_start_pfn;
+		zone_end = zone->zone_start_pfn + zone->spanned_pages;
 
-		zbm->next = zbmlist;
-		zbmlist = zbm;
+		list_for_each_entry(ext, list, hook)
+			if (zone_start <= ext->end)
+				break;
+
+		if (&ext->hook == list || zone_end < ext->start) {
+			/* New extent is necessary */
+			struct mem_extent *new_ext;
+
+			new_ext = kzalloc(sizeof(struct mem_extent), gfp_mask);
+			if (!new_ext) {
+				free_mem_extents(list);
+				return -ENOMEM;
+			}
+			new_ext->start = zone_start;
+			new_ext->end = zone_end;
+			list_add_tail(&new_ext->hook, &ext->hook);
+			continue;
+		}
+
+		/* Merge this zone's range of PFNs with the existing one */
+		if (zone_start < ext->start)
+			ext->start = zone_start;
+		if (zone_end > ext->end)
+			ext->end = zone_end;
+
+		/* More merging may be possible */
+		cur = ext;
+		list_for_each_entry_safe_continue(cur, aux, list, hook) {
+			if (zone_end < cur->start)
+				break;
+			if (zone_end < cur->end)
+				ext->end = cur->end;
+			list_del(&cur->hook);
+			kfree(cur);
+		}
 	}
-	return zbmlist;
+
+	return 0;
 }
 
 /**
   *	memory_bm_create - allocate memory for a memory bitmap
   */
-
 static int
 memory_bm_create(struct memory_bitmap *bm, gfp_t gfp_mask, int safe_needed)
 {
 	struct chain_allocator ca;
-	struct zone *zone;
-	struct zone_bitmap *zone_bm;
-	struct bm_block *bb;
-	unsigned int nr;
+	struct list_head mem_extents;
+	struct mem_extent *ext;
+	int error;
 
 	chain_init(&ca, gfp_mask, safe_needed);
+	INIT_LIST_HEAD(&bm->blocks);
 
-	/* Compute the number of zones */
-	nr = 0;
-	for_each_zone(zone)
-		if (populated_zone(zone))
-			nr++;
-
-	/* Allocate the list of zones bitmap objects */
-	zone_bm = create_zone_bm_list(nr, &ca);
-	bm->zone_bm_list = zone_bm;
-	if (!zone_bm) {
-		chain_free(&ca, PG_UNSAFE_CLEAR);
-		return -ENOMEM;
-	}
-
-	/* Initialize the zone bitmap objects */
-	for_each_zone(zone) {
-		unsigned long pfn;
+	error = create_mem_extents(&mem_extents, gfp_mask);
+	if (error)
+		return error;
 
-		if (!populated_zone(zone))
-			continue;
+	list_for_each_entry(ext, &mem_extents, hook) {
+		struct bm_block *bb;
+		unsigned long pfn = ext->start;
+		unsigned long pages = ext->end - ext->start;
 
-		zone_bm->start_pfn = zone->zone_start_pfn;
-		zone_bm->end_pfn = zone->zone_start_pfn + zone->spanned_pages;
-		/* Allocate the list of bitmap block objects */
-		nr = DIV_ROUND_UP(zone->spanned_pages, BM_BITS_PER_BLOCK);
-		bb = create_bm_block_list(nr, &ca);
-		zone_bm->bm_blocks = bb;
-		zone_bm->cur_block = bb;
-		if (!bb)
-			goto Free;
+		bb = list_entry(bm->blocks.prev, struct bm_block, hook);
 
-		nr = zone->spanned_pages;
-		pfn = zone->zone_start_pfn;
-		/* Initialize the bitmap block objects */
-		while (bb) {
-			unsigned long *ptr;
+		error = create_bm_block_list(pages, bm->blocks.prev, &ca);
+		if (error)
+			goto Error;
 
-			ptr = get_image_page(gfp_mask, safe_needed);
-			bb->data = ptr;
-			if (!ptr)
-				goto Free;
+		list_for_each_entry_continue(bb, &bm->blocks, hook) {
+			bb->data = get_image_page(gfp_mask, safe_needed);
+			if (!bb->data) {
+				error = -ENOMEM;
+				goto Error;
+			}
 
 			bb->start_pfn = pfn;
-			if (nr >= BM_BITS_PER_BLOCK) {
+			if (pages >= BM_BITS_PER_BLOCK) {
 				pfn += BM_BITS_PER_BLOCK;
-				nr -= BM_BITS_PER_BLOCK;
+				pages -= BM_BITS_PER_BLOCK;
 			} else {
 				/* This is executed only once in the loop */
-				pfn += nr;
+				pfn += pages;
 			}
 			bb->end_pfn = pfn;
-			bb = bb->next;
 		}
-		zone_bm = zone_bm->next;
 	}
+
 	bm->p_list = ca.chain;
 	memory_bm_position_reset(bm);
-	return 0;
+ Exit:
+	free_mem_extents(&mem_extents);
+	return error;
 
- Free:
+ Error:
 	bm->p_list = ca.chain;
 	memory_bm_free(bm, PG_UNSAFE_CLEAR);
-	return -ENOMEM;
+	goto Exit;
 }
 
 /**
   *	memory_bm_free - free memory occupied by the memory bitmap @bm
   */
-
 static void memory_bm_free(struct memory_bitmap *bm, int clear_nosave_free)
 {
-	struct zone_bitmap *zone_bm;
+	struct bm_block *bb;
 
-	/* Free the list of bit blocks for each zone_bitmap object */
-	zone_bm = bm->zone_bm_list;
-	while (zone_bm) {
-		struct bm_block *bb;
+	list_for_each_entry(bb, &bm->blocks, hook)
+		if (bb->data)
+			free_image_page(bb->data, clear_nosave_free);
 
-		bb = zone_bm->bm_blocks;
-		while (bb) {
-			if (bb->data)
-				free_image_page(bb->data, clear_nosave_free);
-			bb = bb->next;
-		}
-		zone_bm = zone_bm->next;
-	}
 	free_list_of_pages(bm->p_list, clear_nosave_free);
-	bm->zone_bm_list = NULL;
+
+	INIT_LIST_HEAD(&bm->blocks);
 }
 
 /**
@@ -437,38 +452,33 @@ static void memory_bm_free(struct memory_bitmap *bm, int clear_nosave_free)
  *	to given pfn.  The cur_zone_bm member of @bm and the cur_block member
  *	of @bm->cur_zone_bm are updated.
  */
-
 static int memory_bm_find_bit(struct memory_bitmap *bm, unsigned long pfn,
 				void **addr, unsigned int *bit_nr)
 {
-	struct zone_bitmap *zone_bm;
 	struct bm_block *bb;
 
-	/* Check if the pfn is from the current zone */
-	zone_bm = bm->cur.zone_bm;
-	if (pfn < zone_bm->start_pfn || pfn >= zone_bm->end_pfn) {
-		zone_bm = bm->zone_bm_list;
-		/* We don't assume that the zones are sorted by pfns */
-		while (pfn < zone_bm->start_pfn || pfn >= zone_bm->end_pfn) {
-			zone_bm = zone_bm->next;
-
-			if (!zone_bm)
-				return -EFAULT;
-		}
-		bm->cur.zone_bm = zone_bm;
-	}
-	/* Check if the pfn corresponds to the current bitmap block */
-	bb = zone_bm->cur_block;
+	/*
+	 * Check if the pfn corresponds to the current bitmap block and find
+	 * the block where it fits if this is not the case.
+	 */
+	bb = bm->cur.block;
 	if (pfn < bb->start_pfn)
-		bb = zone_bm->bm_blocks;
+		list_for_each_entry_continue_reverse(bb, &bm->blocks, hook)
+			if (pfn >= bb->start_pfn)
+				break;
 
-	while (pfn >= bb->end_pfn) {
-		bb = bb->next;
+	if (pfn >= bb->end_pfn)
+		list_for_each_entry_continue(bb, &bm->blocks, hook)
+			if (pfn >= bb->start_pfn && pfn < bb->end_pfn)
+				break;
 
-		BUG_ON(!bb);
-	}
-	zone_bm->cur_block = bb;
+	if (&bb->hook == &bm->blocks)
+		return -EFAULT;
+
+	/* The block has been found */
+	bm->cur.block = bb;
 	pfn -= bb->start_pfn;
+	bm->cur.bit = pfn + 1;
 	*bit_nr = pfn;
 	*addr = bb->data;
 	return 0;
@@ -538,29 +548,21 @@ static bool memory_bm_pfn_present(struct memory_bitmap *bm, unsigned long pfn)
 
 static unsigned long memory_bm_next_pfn(struct memory_bitmap *bm)
 {
-	struct zone_bitmap *zone_bm;
 	struct bm_block *bb;
 	int bit;
 
+	bb = bm->cur.block;
 	do {
-		bb = bm->cur.block;
-		do {
-			bit = bm->cur.bit;
-			bit = find_next_bit(bb->data, bm_block_bits(bb), bit);
-			if (bit < bm_block_bits(bb))
-				goto Return_pfn;
-
-			bb = bb->next;
-			bm->cur.block = bb;
-			bm->cur.bit = 0;
-		} while (bb);
-		zone_bm = bm->cur.zone_bm->next;
-		if (zone_bm) {
-			bm->cur.zone_bm = zone_bm;
-			bm->cur.block = zone_bm->bm_blocks;
-			bm->cur.bit = 0;
-		}
-	} while (zone_bm);
+		bit = bm->cur.bit;
+		bit = find_next_bit(bb->data, bm_block_bits(bb), bit);
+		if (bit < bm_block_bits(bb))
+			goto Return_pfn;
+
+		bb = list_entry(bb->hook.next, struct bm_block, hook);
+		bm->cur.block = bb;
+		bm->cur.bit = 0;
+	} while (&bb->hook != &bm->blocks);
+
 	memory_bm_position_reset(bm);
 	return BM_END_OF_MAP;
 
@@ -816,8 +818,7 @@ static unsigned int count_free_highmem_pages(void)
  *	We should save the page if it isn't Nosave or NosaveFree, or Reserved,
  *	and it isn't a part of a free chunk of pages.
  */
-
-static struct page *saveable_highmem_page(unsigned long pfn)
+static struct page *saveable_highmem_page(struct zone *zone, unsigned long pfn)
 {
 	struct page *page;
 
@@ -825,6 +826,8 @@ static struct page *saveable_highmem_page(unsigned long pfn)
 		return NULL;
 
 	page = pfn_to_page(pfn);
+	if (page_zone(page) != zone)
+		return NULL;
 
 	BUG_ON(!PageHighMem(page));
 
@@ -854,13 +857,16 @@ unsigned int count_highmem_pages(void)
 		mark_free_pages(zone);
 		max_zone_pfn = zone->zone_start_pfn + zone->spanned_pages;
 		for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
-			if (saveable_highmem_page(pfn))
+			if (saveable_highmem_page(zone, pfn))
 				n++;
 	}
 	return n;
 }
 #else
-static inline void *saveable_highmem_page(unsigned long pfn) { return NULL; }
+static inline void *saveable_highmem_page(struct zone *z, unsigned long p)
+{
+	return NULL;
+}
 #endif /* CONFIG_HIGHMEM */
 
 /**
@@ -871,8 +877,7 @@ static inline void *saveable_highmem_page(unsigned long pfn) { return NULL; }
  *	of pages statically defined as 'unsaveable', and it isn't a part of
  *	a free chunk of pages.
  */
-
-static struct page *saveable_page(unsigned long pfn)
+static struct page *saveable_page(struct zone *zone, unsigned long pfn)
 {
 	struct page *page;
 
@@ -880,6 +885,8 @@ static struct page *saveable_page(unsigned long pfn)
 		return NULL;
 
 	page = pfn_to_page(pfn);
+	if (page_zone(page) != zone)
+		return NULL;
 
 	BUG_ON(PageHighMem(page));
 
@@ -911,7 +918,7 @@ unsigned int count_data_pages(void)
 		mark_free_pages(zone);
 		max_zone_pfn = zone->zone_start_pfn + zone->spanned_pages;
 		for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
-			if(saveable_page(pfn))
+			if (saveable_page(zone, pfn))
 				n++;
 	}
 	return n;
@@ -952,7 +959,7 @@ static inline struct page *
 page_is_saveable(struct zone *zone, unsigned long pfn)
 {
 	return is_highmem(zone) ?
-			saveable_highmem_page(pfn) : saveable_page(pfn);
+		saveable_highmem_page(zone, pfn) : saveable_page(zone, pfn);
 }
 
 static void copy_data_page(unsigned long dst_pfn, unsigned long src_pfn)
@@ -983,7 +990,7 @@ static void copy_data_page(unsigned long dst_pfn, unsigned long src_pfn)
 	}
 }
 #else
-#define page_is_saveable(zone, pfn)	saveable_page(pfn)
+#define page_is_saveable(zone, pfn)	saveable_page(zone, pfn)
 
 static inline void copy_data_page(unsigned long dst_pfn, unsigned long src_pfn)
 {