X-Git-Url: http://git.cascardo.info/?a=blobdiff_plain;f=kernel%2Fpower%2Fsnapshot.c;h=d90df926b59fbdf8e76d057d85b55b31ef615f1d;hb=4c0b6c10fbaf0c82efe2a7ba6c236c633d4f2ed7;hp=3a970604308ff5365f431e8190d1b82f7ac306d1;hpb=024f35c55233fb6041e2b31165271f5b941802e6;p=cascardo%2Flinux.git

diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 3a970604308f..d90df926b59f 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -38,6 +38,43 @@
 
 #include "power.h"
 
+#ifdef CONFIG_DEBUG_RODATA
+static bool hibernate_restore_protection;
+static bool hibernate_restore_protection_active;
+
+void enable_restore_image_protection(void)
+{
+	hibernate_restore_protection = true;
+}
+
+static inline void hibernate_restore_protection_begin(void)
+{
+	hibernate_restore_protection_active = hibernate_restore_protection;
+}
+
+static inline void hibernate_restore_protection_end(void)
+{
+	hibernate_restore_protection_active = false;
+}
+
+static inline void hibernate_restore_protect_page(void *page_address)
+{
+	if (hibernate_restore_protection_active)
+		set_memory_ro((unsigned long)page_address, 1);
+}
+
+static inline void hibernate_restore_unprotect_page(void *page_address)
+{
+	if (hibernate_restore_protection_active)
+		set_memory_rw((unsigned long)page_address, 1);
+}
+#else
+static inline void hibernate_restore_protection_begin(void) {}
+static inline void hibernate_restore_protection_end(void) {}
+static inline void hibernate_restore_protect_page(void *page_address) {}
+static inline void hibernate_restore_unprotect_page(void *page_address) {}
+#endif /* CONFIG_DEBUG_RODATA */
+
 static int swsusp_page_is_free(struct page *);
 static void swsusp_set_page_forbidden(struct page *);
 static void swsusp_unset_page_forbidden(struct page *);
@@ -67,25 +104,32 @@ void __init hibernate_image_size_init(void)
 	image_size = ((totalram_pages * 2) / 5) * PAGE_SIZE;
 }
 
-/* List of PBEs needed for restoring the pages that were allocated before
+/*
+ * List of PBEs needed for restoring the pages that were allocated before
  * the suspend and included in the suspend image, but have also been
  * allocated by the "resume" kernel, so their contents cannot be written
  * directly to their "original" page frames.
  */
 struct pbe *restore_pblist;
 
-/* Pointer to an auxiliary buffer (1 page) */
-static void *buffer;
+/* struct linked_page is used to build chains of pages */
 
-/**
- *	@safe_needed - on resume, for storing the PBE list and the image,
- *	we can only use memory pages that do not conflict with the pages
- *	used before suspend.  The unsafe pages have PageNosaveFree set
- *	and we count them using unsafe_pages.
- *
- *	Each allocated image page is marked as PageNosave and PageNosaveFree
- *	so that swsusp_free() can release it.
+#define LINKED_PAGE_DATA_SIZE	(PAGE_SIZE - sizeof(void *))
+
+struct linked_page {
+	struct linked_page *next;
+	char data[LINKED_PAGE_DATA_SIZE];
+} __packed;
+
+/*
+ * List of "safe" pages (ie. pages that were not used by the image kernel
+ * before hibernation) that may be used as temporary storage for image kernel
+ * memory contents.
  */
+static struct linked_page *safe_pages_list;
+
+/* Pointer to an auxiliary buffer (1 page) */
+static void *buffer;
 
 #define PG_ANY		0
 #define PG_SAFE		1
@@ -94,6 +138,19 @@ static void *buffer;
 
 static unsigned int allocated_unsafe_pages;
 
+/**
+ * get_image_page - Allocate a page for a hibernation image.
+ * @gfp_mask: GFP mask for the allocation.
+ * @safe_needed: Get pages that were not used before hibernation (restore only)
+ *
+ * During image restoration, for storing the PBE list and the image data, we can
+ * only use memory pages that do not conflict with the pages used before
+ * hibernation.  The "unsafe" pages have PageNosaveFree set and we count them
+ * using allocated_unsafe_pages.
+ *
+ * Each allocated image page is marked as PageNosave and PageNosaveFree so that
+ * swsusp_free() can release it.
+ */
 static void *get_image_page(gfp_t gfp_mask, int safe_needed)
 {
 	void *res;
@@ -113,9 +170,21 @@ static void *get_image_page(gfp_t gfp_mask, int safe_needed)
 	return res;
 }
 
+static void *__get_safe_page(gfp_t gfp_mask)
+{
+	if (safe_pages_list) {
+		void *ret = safe_pages_list;
+
+		safe_pages_list = safe_pages_list->next;
+		memset(ret, 0, PAGE_SIZE);
+		return ret;
+	}
+	return get_image_page(gfp_mask, PG_SAFE);
+}
+
 unsigned long get_safe_page(gfp_t gfp_mask)
 {
-	return (unsigned long)get_image_page(gfp_mask, PG_SAFE);
+	return (unsigned long)__get_safe_page(gfp_mask);
 }
 
 static struct page *alloc_image_page(gfp_t gfp_mask)
@@ -130,11 +199,22 @@ static struct page *alloc_image_page(gfp_t gfp_mask)
 	return page;
 }
 
+static void recycle_safe_page(void *page_address)
+{
+	struct linked_page *lp = page_address;
+
+	lp->next = safe_pages_list;
+	safe_pages_list = lp;
+}
+
 /**
- *	free_image_page - free page represented by @addr, allocated with
- *	get_image_page (page flags set by it must be cleared)
+ * free_image_page - Free a page allocated for hibernation image.
+ * @addr: Address of the page to free.
+ * @clear_nosave_free: If set, clear the PageNosaveFree bit for the page.
+ *
+ * The page to free should have been allocated by get_image_page() (page flags
+ * set by it are affected).
  */
-
 static inline void free_image_page(void *addr, int clear_nosave_free)
 {
 	struct page *page;
@@ -150,17 +230,8 @@ static inline void free_image_page(void *addr, int clear_nosave_free)
 	__free_page(page);
 }
 
-/* struct linked_page is used to build chains of pages */
-
-#define LINKED_PAGE_DATA_SIZE	(PAGE_SIZE - sizeof(void *))
-
-struct linked_page {
-	struct linked_page *next;
-	char data[LINKED_PAGE_DATA_SIZE];
-} __packed;
-
-static inline void
-free_list_of_pages(struct linked_page *list, int clear_page_nosave)
+static inline void free_list_of_pages(struct linked_page *list,
+				      int clear_page_nosave)
 {
 	while (list) {
 		struct linked_page *lp = list->next;
@@ -170,30 +241,28 @@ free_list_of_pages(struct linked_page *list, int clear_page_nosave)
 	}
 }
 
-/**
-  *	struct chain_allocator is used for allocating small objects out of
-  *	a linked list of pages called 'the chain'.
-  *
-  *	The chain grows each time when there is no room for a new object in
-  *	the current page.  The allocated objects cannot be freed individually.
-  *	It is only possible to free them all at once, by freeing the entire
-  *	chain.
-  *
-  *	NOTE: The chain allocator may be inefficient if the allocated objects
-  *	are not much smaller than PAGE_SIZE.
-  */
-
+/*
+ * struct chain_allocator is used for allocating small objects out of
+ * a linked list of pages called 'the chain'.
+ *
+ * The chain grows each time when there is no room for a new object in
+ * the current page.  The allocated objects cannot be freed individually.
+ * It is only possible to free them all at once, by freeing the entire
+ * chain.
+ *
+ * NOTE: The chain allocator may be inefficient if the allocated objects
+ * are not much smaller than PAGE_SIZE.
+ */
 struct chain_allocator {
 	struct linked_page *chain;	/* the chain */
 	unsigned int used_space;	/* total size of objects allocated out
-					 * of the current page
-					 */
+					   of the current page */
 	gfp_t gfp_mask;		/* mask for allocating pages */
 	int safe_needed;	/* if set, only "safe" pages are allocated */
 };
 
-static void
-chain_init(struct chain_allocator *ca, gfp_t gfp_mask, int safe_needed)
+static void chain_init(struct chain_allocator *ca, gfp_t gfp_mask,
+		       int safe_needed)
 {
 	ca->chain = NULL;
 	ca->used_space = LINKED_PAGE_DATA_SIZE;
@@ -208,7 +277,8 @@ static void *chain_alloc(struct chain_allocator *ca, unsigned int size)
 	if (LINKED_PAGE_DATA_SIZE - ca->used_space < size) {
 		struct linked_page *lp;
 
-		lp = get_image_page(ca->gfp_mask, ca->safe_needed);
+		lp = ca->safe_needed ? __get_safe_page(ca->gfp_mask) :
+					get_image_page(ca->gfp_mask, PG_ANY);
 		if (!lp)
 			return NULL;
 
@@ -222,44 +292,44 @@ static void *chain_alloc(struct chain_allocator *ca, unsigned int size)
 }
 
 /**
- *	Data types related to memory bitmaps.
+ * Data types related to memory bitmaps.
  *
- *	Memory bitmap is a structure consiting of many linked lists of
- *	objects.  The main list's elements are of type struct zone_bitmap
- *	and each of them corresonds to one zone.  For each zone bitmap
- *	object there is a list of objects of type struct bm_block that
- *	represent each blocks of bitmap in which information is stored.
+ * Memory bitmap is a structure consiting of many linked lists of
+ * objects.  The main list's elements are of type struct zone_bitmap
+ * and each of them corresonds to one zone.  For each zone bitmap
+ * object there is a list of objects of type struct bm_block that
+ * represent each blocks of bitmap in which information is stored.
  *
- *	struct memory_bitmap contains a pointer to the main list of zone
- *	bitmap objects, a struct bm_position used for browsing the bitmap,
- *	and a pointer to the list of pages used for allocating all of the
- *	zone bitmap objects and bitmap block objects.
+ * struct memory_bitmap contains a pointer to the main list of zone
+ * bitmap objects, a struct bm_position used for browsing the bitmap,
+ * and a pointer to the list of pages used for allocating all of the
+ * zone bitmap objects and bitmap block objects.
  *
- *	NOTE: It has to be possible to lay out the bitmap in memory
- *	using only allocations of order 0.  Additionally, the bitmap is
- *	designed to work with arbitrary number of zones (this is over the
- *	top for now, but let's avoid making unnecessary assumptions ;-).
+ * NOTE: It has to be possible to lay out the bitmap in memory
+ * using only allocations of order 0.  Additionally, the bitmap is
+ * designed to work with arbitrary number of zones (this is over the
+ * top for now, but let's avoid making unnecessary assumptions ;-).
  *
- *	struct zone_bitmap contains a pointer to a list of bitmap block
- *	objects and a pointer to the bitmap block object that has been
- *	most recently used for setting bits.  Additionally, it contains the
- *	pfns that correspond to the start and end of the represented zone.
+ * struct zone_bitmap contains a pointer to a list of bitmap block
+ * objects and a pointer to the bitmap block object that has been
+ * most recently used for setting bits.  Additionally, it contains the
+ * PFNs that correspond to the start and end of the represented zone.
  *
- *	struct bm_block contains a pointer to the memory page in which
- *	information is stored (in the form of a block of bitmap)
- *	It also contains the pfns that correspond to the start and end of
- *	the represented memory area.
+ * struct bm_block contains a pointer to the memory page in which
+ * information is stored (in the form of a block of bitmap)
+ * It also contains the pfns that correspond to the start and end of
+ * the represented memory area.
  *
- *	The memory bitmap is organized as a radix tree to guarantee fast random
- *	access to the bits. There is one radix tree for each zone (as returned
- *	from create_mem_extents).
+ * The memory bitmap is organized as a radix tree to guarantee fast random
+ * access to the bits. There is one radix tree for each zone (as returned
+ * from create_mem_extents).
  *
- *	One radix tree is represented by one struct mem_zone_bm_rtree. There are
- *	two linked lists for the nodes of the tree, one for the inner nodes and
- *	one for the leave nodes. The linked leave nodes are used for fast linear
- *	access of the memory bitmap.
+ * One radix tree is represented by one struct mem_zone_bm_rtree. There are
+ * two linked lists for the nodes of the tree, one for the inner nodes and
+ * one for the leave nodes. The linked leave nodes are used for fast linear
+ * access of the memory bitmap.
  *
- *	The struct rtree_node represents one node of the radix tree.
+ * The struct rtree_node represents one node of the radix tree.
  */
 
 #define BM_END_OF_MAP	(~0UL)
@@ -305,9 +375,8 @@ struct bm_position {
 struct memory_bitmap {
 	struct list_head zones;
 	struct linked_page *p_list;	/* list of pages used to store zone
-					 * bitmap objects and bitmap block
-					 * objects
-					 */
+					   bitmap objects and bitmap block
+					   objects */
 	struct bm_position cur;	/* most recently used bit position */
 };
 
@@ -321,12 +390,12 @@ struct memory_bitmap {
 #endif
 #define BM_RTREE_LEVEL_MASK	((1UL << BM_RTREE_LEVEL_SHIFT) - 1)
 
-/*
- *	alloc_rtree_node - Allocate a new node and add it to the radix tree.
+/**
+ * alloc_rtree_node - Allocate a new node and add it to the radix tree.
  *
- *	This function is used to allocate inner nodes as well as the
- *	leave nodes of the radix tree. It also adds the node to the
- *	corresponding linked list passed in by the *list parameter.
+ * This function is used to allocate inner nodes as well as the
+ * leave nodes of the radix tree. It also adds the node to the
+ * corresponding linked list passed in by the *list parameter.
  */
 static struct rtree_node *alloc_rtree_node(gfp_t gfp_mask, int safe_needed,
 					   struct chain_allocator *ca,
@@ -347,12 +416,12 @@ static struct rtree_node *alloc_rtree_node(gfp_t gfp_mask, int safe_needed,
 	return node;
 }
 
-/*
- *	add_rtree_block - Add a new leave node to the radix tree
+/**
+ * add_rtree_block - Add a new leave node to the radix tree.
  *
- *	The leave nodes need to be allocated in order to keep the leaves
- *	linked list in order. This is guaranteed by the zone->blocks
- *	counter.
+ * The leave nodes need to be allocated in order to keep the leaves
+ * linked list in order. This is guaranteed by the zone->blocks
+ * counter.
  */
 static int add_rtree_block(struct mem_zone_bm_rtree *zone, gfp_t gfp_mask,
 			   int safe_needed, struct chain_allocator *ca)
@@ -417,17 +486,18 @@ static int add_rtree_block(struct mem_zone_bm_rtree *zone, gfp_t gfp_mask,
 static void free_zone_bm_rtree(struct mem_zone_bm_rtree *zone,
 			       int clear_nosave_free);
 
-/*
- *	create_zone_bm_rtree - create a radix tree for one zone
+/**
+ * create_zone_bm_rtree - Create a radix tree for one zone.
  *
- *	Allocated the mem_zone_bm_rtree structure and initializes it.
- *	This function also allocated and builds the radix tree for the
- *	zone.
+ * Allocated the mem_zone_bm_rtree structure and initializes it.
+ * This function also allocated and builds the radix tree for the
+ * zone.
  */
-static struct mem_zone_bm_rtree *
-create_zone_bm_rtree(gfp_t gfp_mask, int safe_needed,
-		     struct chain_allocator *ca,
-		     unsigned long start, unsigned long end)
+static struct mem_zone_bm_rtree *create_zone_bm_rtree(gfp_t gfp_mask,
+						      int safe_needed,
+						      struct chain_allocator *ca,
+						      unsigned long start,
+						      unsigned long end)
 {
 	struct mem_zone_bm_rtree *zone;
 	unsigned int i, nr_blocks;
@@ -454,12 +524,12 @@ create_zone_bm_rtree(gfp_t gfp_mask, int safe_needed,
 	return zone;
 }
 
-/*
- *	free_zone_bm_rtree - Free the memory of the radix tree
+/**
+ * free_zone_bm_rtree - Free the memory of the radix tree.
  *
- *	Free all node pages of the radix tree. The mem_zone_bm_rtree
- *	structure itself is not freed here nor are the rtree_node
- *	structs.
+ * Free all node pages of the radix tree. The mem_zone_bm_rtree
+ * structure itself is not freed here nor are the rtree_node
+ * structs.
  */
 static void free_zone_bm_rtree(struct mem_zone_bm_rtree *zone,
 			       int clear_nosave_free)
@@ -492,8 +562,8 @@ struct mem_extent {
 };
 
 /**
- *	free_mem_extents - free a list of memory extents
- *	@list - list of extents to empty
+ * free_mem_extents - Free a list of memory extents.
+ * @list: List of extents to free.
  */
 static void free_mem_extents(struct list_head *list)
 {
@@ -506,10 +576,11 @@ static void free_mem_extents(struct list_head *list)
 }
 
 /**
- *	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
+ * create_mem_extents - Create a list of memory extents.
+ * @list: List to put the extents into.
+ * @gfp_mask: Mask to use for memory allocations.
+ *
+ * The extents represent contiguous ranges of PFNs.
  */
 static int create_mem_extents(struct list_head *list, gfp_t gfp_mask)
 {
@@ -565,10 +636,10 @@ static int create_mem_extents(struct list_head *list, gfp_t gfp_mask)
 }
 
 /**
-  *	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)
+ * 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 list_head mem_extents;
@@ -607,8 +678,9 @@ memory_bm_create(struct memory_bitmap *bm, gfp_t gfp_mask, int safe_needed)
 }
 
 /**
-  *	memory_bm_free - free memory occupied by the memory bitmap @bm
-  */
+ * memory_bm_free - Free memory occupied by the memory bitmap.
+ * @bm: Memory bitmap.
+ */
 static void memory_bm_free(struct memory_bitmap *bm, int clear_nosave_free)
 {
 	struct mem_zone_bm_rtree *zone;
@@ -622,14 +694,13 @@ static void memory_bm_free(struct memory_bitmap *bm, int clear_nosave_free)
 }
 
 /**
- *	memory_bm_find_bit - Find the bit for pfn in the memory
- *			     bitmap
+ * memory_bm_find_bit - Find the bit for a given PFN in a memory bitmap.
  *
- *	Find the bit in the bitmap @bm that corresponds to given pfn.
- *	The cur.zone, cur.block and cur.node_pfn member of @bm are
- *	updated.
- *	It walks the radix tree to find the page which contains the bit for
- *	pfn and returns the bit position in **addr and *bit_nr.
+ * Find the bit in memory bitmap @bm that corresponds to the given PFN.
+ * The cur.zone, cur.block and cur.node_pfn members of @bm are updated.
+ *
+ * Walk the radix tree to find the page containing the bit that represents @pfn
+ * and return the position of the bit in @addr and @bit_nr.
  */
 static int memory_bm_find_bit(struct memory_bitmap *bm, unsigned long pfn,
 			      void **addr, unsigned int *bit_nr)
@@ -658,10 +729,9 @@ static int memory_bm_find_bit(struct memory_bitmap *bm, unsigned long pfn,
 
 zone_found:
 	/*
-	 * We have a zone. Now walk the radix tree to find the leave
-	 * node for our pfn.
+	 * We have found the zone. Now walk the radix tree to find the leaf node
+	 * for our PFN.
 	 */
-
 	node = bm->cur.node;
 	if (((pfn - zone->start_pfn) & ~BM_BLOCK_MASK) == bm->cur.node_pfn)
 		goto node_found;
@@ -754,14 +824,14 @@ static bool memory_bm_pfn_present(struct memory_bitmap *bm, unsigned long pfn)
 }
 
 /*
- *	rtree_next_node - Jumps to the next leave node
+ * rtree_next_node - Jump to the next leaf node.
  *
- *	Sets the position to the beginning of the next node in the
- *	memory bitmap. This is either the next node in the current
- *	zone's radix tree or the first node in the radix tree of the
- *	next zone.
+ * Set the position to the beginning of the next node in the
+ * memory bitmap. This is either the next node in the current
+ * zone's radix tree or the first node in the radix tree of the
+ * next zone.
  *
- *	Returns true if there is a next node, false otherwise.
+ * Return true if there is a next node, false otherwise.
  */
 static bool rtree_next_node(struct memory_bitmap *bm)
 {
@@ -790,14 +860,15 @@ static bool rtree_next_node(struct memory_bitmap *bm)
 }
 
 /**
- *	memory_bm_rtree_next_pfn - Find the next set bit in the bitmap @bm
+ * memory_bm_rtree_next_pfn - Find the next set bit in a memory bitmap.
+ * @bm: Memory bitmap.
  *
- *	Starting from the last returned position this function searches
- *	for the next set bit in the memory bitmap and returns its
- *	number. If no more bit is set BM_END_OF_MAP is returned.
+ * Starting from the last returned position this function searches for the next
+ * set bit in @bm and returns the PFN represented by it.  If no more bits are
+ * set, BM_END_OF_MAP is returned.
  *
- *	It is required to run memory_bm_position_reset() before the
- *	first call to this function.
+ * It is required to run memory_bm_position_reset() before the first call to
+ * this function for the given memory bitmap.
  */
 static unsigned long memory_bm_next_pfn(struct memory_bitmap *bm)
 {
@@ -819,11 +890,10 @@ static unsigned long memory_bm_next_pfn(struct memory_bitmap *bm)
 	return BM_END_OF_MAP;
 }
 
-/**
- *	This structure represents a range of page frames the contents of which
- *	should not be saved during the suspend.
+/*
+ * This structure represents a range of page frames the contents of which
+ * should not be saved during hibernation.
  */
-
 struct nosave_region {
 	struct list_head list;
 	unsigned long start_pfn;
@@ -832,15 +902,42 @@ struct nosave_region {
 
 static LIST_HEAD(nosave_regions);
 
+static void recycle_zone_bm_rtree(struct mem_zone_bm_rtree *zone)
+{
+	struct rtree_node *node;
+
+	list_for_each_entry(node, &zone->nodes, list)
+		recycle_safe_page(node->data);
+
+	list_for_each_entry(node, &zone->leaves, list)
+		recycle_safe_page(node->data);
+}
+
+static void memory_bm_recycle(struct memory_bitmap *bm)
+{
+	struct mem_zone_bm_rtree *zone;
+	struct linked_page *p_list;
+
+	list_for_each_entry(zone, &bm->zones, list)
+		recycle_zone_bm_rtree(zone);
+
+	p_list = bm->p_list;
+	while (p_list) {
+		struct linked_page *lp = p_list;
+
+		p_list = lp->next;
+		recycle_safe_page(lp);
+	}
+}
+
 /**
- *	register_nosave_region - register a range of page frames the contents
- *	of which should not be saved during the suspend (to be used in the early
- *	initialization code)
+ * register_nosave_region - Register a region of unsaveable memory.
+ *
+ * Register a range of page frames the contents of which should not be saved
+ * during hibernation (to be used in the early initialization code).
  */
-
-void __init
-__register_nosave_region(unsigned long start_pfn, unsigned long end_pfn,
-			 int use_kmalloc)
+void __init __register_nosave_region(unsigned long start_pfn,
+				     unsigned long end_pfn, int use_kmalloc)
 {
 	struct nosave_region *region;
 
@@ -857,12 +954,13 @@ __register_nosave_region(unsigned long start_pfn, unsigned long end_pfn,
 		}
 	}
 	if (use_kmalloc) {
-		/* during init, this shouldn't fail */
+		/* During init, this shouldn't fail */
 		region = kmalloc(sizeof(struct nosave_region), GFP_KERNEL);
 		BUG_ON(!region);
-	} else
+	} else {
 		/* This allocation cannot fail */
 		region = memblock_virt_alloc(sizeof(struct nosave_region), 0);
+	}
 	region->start_pfn = start_pfn;
 	region->end_pfn = end_pfn;
 	list_add_tail(&region->list, &nosave_regions);
@@ -923,10 +1021,12 @@ static void swsusp_unset_page_forbidden(struct page *page)
 }
 
 /**
- *	mark_nosave_pages - set bits corresponding to the page frames the
- *	contents of which should not be saved in a given bitmap.
+ * mark_nosave_pages - Mark pages that should not be saved.
+ * @bm: Memory bitmap.
+ *
+ * Set the bits in @bm that correspond to the page frames the contents of which
+ * should not be saved.
  */
-
 static void mark_nosave_pages(struct memory_bitmap *bm)
 {
 	struct nosave_region *region;
@@ -956,13 +1056,13 @@ static void mark_nosave_pages(struct memory_bitmap *bm)
 }
 
 /**
- *	create_basic_memory_bitmaps - create bitmaps needed for marking page
- *	frames that should not be saved and free page frames.  The pointers
- *	forbidden_pages_map and free_pages_map are only modified if everything
- *	goes well, because we don't want the bits to be used before both bitmaps
- *	are set up.
+ * create_basic_memory_bitmaps - Create bitmaps to hold basic page information.
+ *
+ * Create bitmaps needed for marking page frames that should not be saved and
+ * free page frames.  The forbidden_pages_map and free_pages_map pointers are
+ * only modified if everything goes well, because we don't want the bits to be
+ * touched before both bitmaps are set up.
  */
-
 int create_basic_memory_bitmaps(void)
 {
 	struct memory_bitmap *bm1, *bm2;
@@ -1007,12 +1107,12 @@ int create_basic_memory_bitmaps(void)
 }
 
 /**
- *	free_basic_memory_bitmaps - free memory bitmaps allocated by
- *	create_basic_memory_bitmaps().  The auxiliary pointers are necessary
- *	so that the bitmaps themselves are not referred to while they are being
- *	freed.
+ * free_basic_memory_bitmaps - Free memory bitmaps holding basic information.
+ *
+ * Free memory bitmaps allocated by create_basic_memory_bitmaps().  The
+ * auxiliary pointers are necessary so that the bitmaps themselves are not
+ * referred to while they are being freed.
  */
-
 void free_basic_memory_bitmaps(void)
 {
 	struct memory_bitmap *bm1, *bm2;
@@ -1033,11 +1133,13 @@ void free_basic_memory_bitmaps(void)
 }
 
 /**
- *	snapshot_additional_pages - estimate the number of additional pages
- *	be needed for setting up the suspend image data structures for given
- *	zone (usually the returned value is greater than the exact number)
+ * snapshot_additional_pages - Estimate the number of extra pages needed.
+ * @zone: Memory zone to carry out the computation for.
+ *
+ * Estimate the number of additional pages needed for setting up a hibernation
+ * image data structures for @zone (usually, the returned value is greater than
+ * the exact number).
  */
-
 unsigned int snapshot_additional_pages(struct zone *zone)
 {
 	unsigned int rtree, nodes;
@@ -1055,10 +1157,10 @@ unsigned int snapshot_additional_pages(struct zone *zone)
 
 #ifdef CONFIG_HIGHMEM
 /**
- *	count_free_highmem_pages - compute the total number of free highmem
- *	pages, system-wide.
+ * count_free_highmem_pages - Compute the total number of free highmem pages.
+ *
+ * The returned number is system-wide.
  */
-
 static unsigned int count_free_highmem_pages(void)
 {
 	struct zone *zone;
@@ -1072,11 +1174,12 @@ static unsigned int count_free_highmem_pages(void)
 }
 
 /**
- *	saveable_highmem_page - Determine whether a highmem page should be
- *	included in the suspend image.
+ * saveable_highmem_page - Check if a highmem page is saveable.
  *
- *	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.
+ * Determine whether a highmem page should be included in a hibernation image.
+ *
+ * We should save the page if it isn't Nosave or NosaveFree, or Reserved,
+ * and it isn't part of a free chunk of pages.
  */
 static struct page *saveable_highmem_page(struct zone *zone, unsigned long pfn)
 {
@@ -1102,10 +1205,8 @@ static struct page *saveable_highmem_page(struct zone *zone, unsigned long pfn)
 }
 
 /**
- *	count_highmem_pages - compute the total number of saveable highmem
- *	pages.
+ * count_highmem_pages - Compute the total number of saveable highmem pages.
  */
-
 static unsigned int count_highmem_pages(void)
 {
 	struct zone *zone;
@@ -1133,12 +1234,14 @@ static inline void *saveable_highmem_page(struct zone *z, unsigned long p)
 #endif /* CONFIG_HIGHMEM */
 
 /**
- *	saveable_page - Determine whether a non-highmem page should be included
- *	in the suspend image.
+ * saveable_page - Check if the given page is saveable.
  *
- *	We should save the page if it isn't Nosave, and is not in the range
- *	of pages statically defined as 'unsaveable', and it isn't a part of
- *	a free chunk of pages.
+ * Determine whether a non-highmem page should be included in a hibernation
+ * image.
+ *
+ * We should save the page if it isn't Nosave, and is not in the range
+ * of pages statically defined as 'unsaveable', and it isn't part of
+ * a free chunk of pages.
  */
 static struct page *saveable_page(struct zone *zone, unsigned long pfn)
 {
@@ -1167,10 +1270,8 @@ static struct page *saveable_page(struct zone *zone, unsigned long pfn)
 }
 
 /**
- *	count_data_pages - compute the total number of saveable non-highmem
- *	pages.
+ * count_data_pages - Compute the total number of saveable non-highmem pages.
  */
-
 static unsigned int count_data_pages(void)
 {
 	struct zone *zone;
@@ -1190,7 +1291,8 @@ static unsigned int count_data_pages(void)
 	return n;
 }
 
-/* This is needed, because copy_page and memcpy are not usable for copying
+/*
+ * This is needed, because copy_page and memcpy are not usable for copying
  * task structs.
  */
 static inline void do_copy_page(long *dst, long *src)
@@ -1201,12 +1303,12 @@ static inline void do_copy_page(long *dst, long *src)
 		*dst++ = *src++;
 }
 
-
 /**
- *	safe_copy_page - check if the page we are going to copy is marked as
- *		present in the kernel page tables (this always is the case if
- *		CONFIG_DEBUG_PAGEALLOC is not set and in that case
- *		kernel_page_present() always returns 'true').
+ * safe_copy_page - Copy a page in a safe way.
+ *
+ * Check if the page we are going to copy is marked as present in the kernel
+ * page tables (this always is the case if CONFIG_DEBUG_PAGEALLOC is not set
+ * and in that case kernel_page_present() always returns 'true').
  */
 static void safe_copy_page(void *dst, struct page *s_page)
 {
@@ -1219,10 +1321,8 @@ static void safe_copy_page(void *dst, struct page *s_page)
 	}
 }
 
-
 #ifdef CONFIG_HIGHMEM
-static inline struct page *
-page_is_saveable(struct zone *zone, unsigned long pfn)
+static inline struct page *page_is_saveable(struct zone *zone, unsigned long pfn)
 {
 	return is_highmem(zone) ?
 		saveable_highmem_page(zone, pfn) : saveable_page(zone, pfn);
@@ -1243,7 +1343,8 @@ static void copy_data_page(unsigned long dst_pfn, unsigned long src_pfn)
 		kunmap_atomic(src);
 	} else {
 		if (PageHighMem(d_page)) {
-			/* Page pointed to by src may contain some kernel
+			/*
+			 * The page pointed to by src may contain some kernel
 			 * data modified by kmap_atomic()
 			 */
 			safe_copy_page(buffer, s_page);
@@ -1265,8 +1366,8 @@ static inline void copy_data_page(unsigned long dst_pfn, unsigned long src_pfn)
 }
 #endif /* CONFIG_HIGHMEM */
 
-static void
-copy_data_pages(struct memory_bitmap *copy_bm, struct memory_bitmap *orig_bm)
+static void copy_data_pages(struct memory_bitmap *copy_bm,
+			    struct memory_bitmap *orig_bm)
 {
 	struct zone *zone;
 	unsigned long pfn;
@@ -1315,12 +1416,11 @@ static struct memory_bitmap orig_bm;
 static struct memory_bitmap copy_bm;
 
 /**
- *	swsusp_free - free pages allocated for the suspend.
+ * swsusp_free - Free pages allocated for hibernation image.
  *
- *	Suspend pages are alocated before the atomic copy is made, so we
- *	need to release them after the resume.
+ * Image pages are alocated before snapshot creation, so they need to be
+ * released after resume.
  */
-
 void swsusp_free(void)
 {
 	unsigned long fb_pfn, fr_pfn;
@@ -1351,6 +1451,7 @@ loop:
 
 		memory_bm_clear_current(forbidden_pages_map);
 		memory_bm_clear_current(free_pages_map);
+		hibernate_restore_unprotect_page(page_address(page));
 		__free_page(page);
 		goto loop;
 	}
@@ -1362,6 +1463,7 @@ out:
 	buffer = NULL;
 	alloc_normal = 0;
 	alloc_highmem = 0;
+	hibernate_restore_protection_end();
 }
 
 /* Helper functions used for the shrinking of memory. */
@@ -1369,7 +1471,7 @@ out:
 #define GFP_IMAGE	(GFP_KERNEL | __GFP_NOWARN)
 
 /**
- * preallocate_image_pages - Allocate a number of pages for hibernation image
+ * preallocate_image_pages - Allocate a number of pages for hibernation image.
  * @nr_pages: Number of page frames to allocate.
  * @mask: GFP flags to use for the allocation.
  *
@@ -1419,7 +1521,7 @@ static unsigned long preallocate_image_highmem(unsigned long nr_pages)
 }
 
 /**
- *  __fraction - Compute (an approximation of) x * (multiplier / base)
+ *  __fraction - Compute (an approximation of) x * (multiplier / base).
  */
 static unsigned long __fraction(u64 x, u64 multiplier, u64 base)
 {
@@ -1429,8 +1531,8 @@ static unsigned long __fraction(u64 x, u64 multiplier, u64 base)
 }
 
 static unsigned long preallocate_highmem_fraction(unsigned long nr_pages,
-						unsigned long highmem,
-						unsigned long total)
+						  unsigned long highmem,
+						  unsigned long total)
 {
 	unsigned long alloc = __fraction(nr_pages, highmem, total);
 
@@ -1443,15 +1545,15 @@ static inline unsigned long preallocate_image_highmem(unsigned long nr_pages)
 }
 
 static inline unsigned long preallocate_highmem_fraction(unsigned long nr_pages,
-						unsigned long highmem,
-						unsigned long total)
+							 unsigned long highmem,
+							 unsigned long total)
 {
 	return 0;
 }
 #endif /* CONFIG_HIGHMEM */
 
 /**
- * free_unnecessary_pages - Release preallocated pages not needed for the image
+ * free_unnecessary_pages - Release preallocated pages not needed for the image.
  */
 static unsigned long free_unnecessary_pages(void)
 {
@@ -1505,7 +1607,7 @@ static unsigned long free_unnecessary_pages(void)
 }
 
 /**
- * minimum_image_size - Estimate the minimum acceptable size of an image
+ * minimum_image_size - Estimate the minimum acceptable size of an image.
  * @saveable: Number of saveable pages in the system.
  *
  * We want to avoid attempting to free too much memory too hard, so estimate the
@@ -1535,7 +1637,7 @@ static unsigned long minimum_image_size(unsigned long saveable)
 }
 
 /**
- * hibernate_preallocate_memory - Preallocate memory for hibernation image
+ * hibernate_preallocate_memory - Preallocate memory for hibernation image.
  *
  * To create a hibernation image it is necessary to make a copy of every page
  * frame in use.  We also need a number of page frames to be free during
@@ -1708,10 +1810,11 @@ int hibernate_preallocate_memory(void)
 
 #ifdef CONFIG_HIGHMEM
 /**
-  *	count_pages_for_highmem - compute the number of non-highmem pages
-  *	that will be necessary for creating copies of highmem pages.
-  */
-
+ * count_pages_for_highmem - Count non-highmem pages needed for copying highmem.
+ *
+ * Compute the number of non-highmem pages that will be necessary for creating
+ * copies of highmem pages.
+ */
 static unsigned int count_pages_for_highmem(unsigned int nr_highmem)
 {
 	unsigned int free_highmem = count_free_highmem_pages() + alloc_highmem;
@@ -1724,15 +1827,12 @@ static unsigned int count_pages_for_highmem(unsigned int nr_highmem)
 	return nr_highmem;
 }
 #else
-static unsigned int
-count_pages_for_highmem(unsigned int nr_highmem) { return 0; }
+static unsigned int count_pages_for_highmem(unsigned int nr_highmem) { return 0; }
 #endif /* CONFIG_HIGHMEM */
 
 /**
- *	enough_free_mem - Make sure we have enough free memory for the
- *	snapshot image.
+ * enough_free_mem - Check if there is enough free memory for the image.
  */
-
 static int enough_free_mem(unsigned int nr_pages, unsigned int nr_highmem)
 {
 	struct zone *zone;
@@ -1751,10 +1851,11 @@ static int enough_free_mem(unsigned int nr_pages, unsigned int nr_highmem)
 
 #ifdef CONFIG_HIGHMEM
 /**
- *	get_highmem_buffer - if there are some highmem pages in the suspend
- *	image, we may need the buffer to copy them and/or load their data.
+ * get_highmem_buffer - Allocate a buffer for highmem pages.
+ *
+ * If there are some highmem pages in the hibernation image, we may need a
+ * buffer to copy them and/or load their data.
  */
-
 static inline int get_highmem_buffer(int safe_needed)
 {
 	buffer = get_image_page(GFP_ATOMIC | __GFP_COLD, safe_needed);
@@ -1762,13 +1863,13 @@ static inline int get_highmem_buffer(int safe_needed)
 }
 
 /**
- *	alloc_highmem_image_pages - allocate some highmem pages for the image.
- *	Try to allocate as many pages as needed, but if the number of free
- *	highmem pages is lesser than that, allocate them all.
+ * alloc_highmem_image_pages - Allocate some highmem pages for the image.
+ *
+ * Try to allocate as many pages as needed, but if the number of free highmem
+ * pages is less than that, allocate them all.
  */
-
-static inline unsigned int
-alloc_highmem_pages(struct memory_bitmap *bm, unsigned int nr_highmem)
+static inline unsigned int alloc_highmem_pages(struct memory_bitmap *bm,
+					       unsigned int nr_highmem)
 {
 	unsigned int to_alloc = count_free_highmem_pages();
 
@@ -1787,25 +1888,24 @@ alloc_highmem_pages(struct memory_bitmap *bm, unsigned int nr_highmem)
 #else
 static inline int get_highmem_buffer(int safe_needed) { return 0; }
 
-static inline unsigned int
-alloc_highmem_pages(struct memory_bitmap *bm, unsigned int n) { return 0; }
+static inline unsigned int alloc_highmem_pages(struct memory_bitmap *bm,
+					       unsigned int n) { return 0; }
 #endif /* CONFIG_HIGHMEM */
 
 /**
- *	swsusp_alloc - allocate memory for the suspend image
+ * swsusp_alloc - Allocate memory for hibernation image.
  *
- *	We first try to allocate as many highmem pages as there are
- *	saveable highmem pages in the system.  If that fails, we allocate
- *	non-highmem pages for the copies of the remaining highmem ones.
+ * We first try to allocate as many highmem pages as there are
+ * saveable highmem pages in the system.  If that fails, we allocate
+ * non-highmem pages for the copies of the remaining highmem ones.
  *
- *	In this approach it is likely that the copies of highmem pages will
- *	also be located in the high memory, because of the way in which
- *	copy_data_pages() works.
+ * In this approach it is likely that the copies of highmem pages will
+ * also be located in the high memory, because of the way in which
+ * copy_data_pages() works.
  */
-
-static int
-swsusp_alloc(struct memory_bitmap *orig_bm, struct memory_bitmap *copy_bm,
-		unsigned int nr_pages, unsigned int nr_highmem)
+static int swsusp_alloc(struct memory_bitmap *orig_bm,
+			struct memory_bitmap *copy_bm,
+			unsigned int nr_pages, unsigned int nr_highmem)
 {
 	if (nr_highmem > 0) {
 		if (get_highmem_buffer(PG_ANY))
@@ -1855,7 +1955,8 @@ asmlinkage __visible int swsusp_save(void)
 		return -ENOMEM;
 	}
 
-	/* During allocating of suspend pagedir, new cold pages may appear.
+	/*
+	 * During allocating of suspend pagedir, new cold pages may appear.
 	 * Kill them.
 	 */
 	drain_local_pages(NULL);
@@ -1918,12 +2019,14 @@ static int init_header(struct swsusp_info *info)
 }
 
 /**
- *	pack_pfns - pfns corresponding to the set bits found in the bitmap @bm
- *	are stored in the array @buf[] (1 page at a time)
+ * pack_pfns - Prepare PFNs for saving.
+ * @bm: Memory bitmap.
+ * @buf: Memory buffer to store the PFNs in.
+ *
+ * PFNs corresponding to set bits in @bm are stored in the area of memory
+ * pointed to by @buf (1 page at a time).
  */
-
-static inline void
-pack_pfns(unsigned long *buf, struct memory_bitmap *bm)
+static inline void pack_pfns(unsigned long *buf, struct memory_bitmap *bm)
 {
 	int j;
 
@@ -1937,22 +2040,21 @@ pack_pfns(unsigned long *buf, struct memory_bitmap *bm)
 }
 
 /**
- *	snapshot_read_next - used for reading the system memory snapshot.
+ * snapshot_read_next - Get the address to read the next image page from.
+ * @handle: Snapshot handle to be used for the reading.
  *
- *	On the first call to it @handle should point to a zeroed
- *	snapshot_handle structure.  The structure gets updated and a pointer
- *	to it should be passed to this function every next time.
+ * On the first call, @handle should point to a zeroed snapshot_handle
+ * structure.  The structure gets populated then and a pointer to it should be
+ * passed to this function every next time.
  *
- *	On success the function returns a positive number.  Then, the caller
- *	is allowed to read up to the returned number of bytes from the memory
- *	location computed by the data_of() macro.
+ * On success, the function returns a positive number.  Then, the caller
+ * is allowed to read up to the returned number of bytes from the memory
+ * location computed by the data_of() macro.
  *
- *	The function returns 0 to indicate the end of data stream condition,
- *	and a negative number is returned on error.  In such cases the
- *	structure pointed to by @handle is not updated and should not be used
- *	any more.
+ * The function returns 0 to indicate the end of the data stream condition,
+ * and negative numbers are returned on errors.  If that happens, the structure
+ * pointed to by @handle is not updated and should not be used any more.
  */
-
 int snapshot_read_next(struct snapshot_handle *handle)
 {
 	if (handle->cur > nr_meta_pages + nr_copy_pages)
@@ -1981,7 +2083,8 @@ int snapshot_read_next(struct snapshot_handle *handle)
 
 		page = pfn_to_page(memory_bm_next_pfn(&copy_bm));
 		if (PageHighMem(page)) {
-			/* Highmem pages are copied to the buffer,
+			/*
+			 * Highmem pages are copied to the buffer,
 			 * because we can't return with a kmapped
 			 * highmem page (we may not be called again).
 			 */
@@ -1999,53 +2102,41 @@ int snapshot_read_next(struct snapshot_handle *handle)
 	return PAGE_SIZE;
 }
 
-/**
- *	mark_unsafe_pages - mark the pages that cannot be used for storing
- *	the image during resume, because they conflict with the pages that
- *	had been used before suspend
- */
-
-static int mark_unsafe_pages(struct memory_bitmap *bm)
+static void duplicate_memory_bitmap(struct memory_bitmap *dst,
+				    struct memory_bitmap *src)
 {
-	struct zone *zone;
-	unsigned long pfn, max_zone_pfn;
+	unsigned long pfn;
 
-	/* Clear page flags */
-	for_each_populated_zone(zone) {
-		max_zone_pfn = zone_end_pfn(zone);
-		for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
-			if (pfn_valid(pfn))
-				swsusp_unset_page_free(pfn_to_page(pfn));
+	memory_bm_position_reset(src);
+	pfn = memory_bm_next_pfn(src);
+	while (pfn != BM_END_OF_MAP) {
+		memory_bm_set_bit(dst, pfn);
+		pfn = memory_bm_next_pfn(src);
 	}
-
-	/* Mark pages that correspond to the "original" pfns as "unsafe" */
-	memory_bm_position_reset(bm);
-	do {
-		pfn = memory_bm_next_pfn(bm);
-		if (likely(pfn != BM_END_OF_MAP)) {
-			if (likely(pfn_valid(pfn)))
-				swsusp_set_page_free(pfn_to_page(pfn));
-			else
-				return -EFAULT;
-		}
-	} while (pfn != BM_END_OF_MAP);
-
-	allocated_unsafe_pages = 0;
-
-	return 0;
 }
 
-static void
-duplicate_memory_bitmap(struct memory_bitmap *dst, struct memory_bitmap *src)
+/**
+ * mark_unsafe_pages - Mark pages that were used before hibernation.
+ *
+ * Mark the pages that cannot be used for storing the image during restoration,
+ * because they conflict with the pages that had been used before hibernation.
+ */
+static void mark_unsafe_pages(struct memory_bitmap *bm)
 {
 	unsigned long pfn;
 
-	memory_bm_position_reset(src);
-	pfn = memory_bm_next_pfn(src);
+	/* Clear the "free"/"unsafe" bit for all PFNs */
+	memory_bm_position_reset(free_pages_map);
+	pfn = memory_bm_next_pfn(free_pages_map);
 	while (pfn != BM_END_OF_MAP) {
-		memory_bm_set_bit(dst, pfn);
-		pfn = memory_bm_next_pfn(src);
+		memory_bm_clear_current(free_pages_map);
+		pfn = memory_bm_next_pfn(free_pages_map);
 	}
+
+	/* Mark pages that correspond to the "original" PFNs as "unsafe" */
+	duplicate_memory_bitmap(free_pages_map, bm);
+
+	allocated_unsafe_pages = 0;
 }
 
 static int check_header(struct swsusp_info *info)
@@ -2063,11 +2154,9 @@ static int check_header(struct swsusp_info *info)
 }
 
 /**
- *	load header - check the image header and copy data from it
+ * load header - Check the image header and copy the data from it.
  */
-
-static int
-load_header(struct swsusp_info *info)
+static int load_header(struct swsusp_info *info)
 {
 	int error;
 
@@ -2081,8 +2170,12 @@ load_header(struct swsusp_info *info)
 }
 
 /**
- *	unpack_orig_pfns - for each element of @buf[] (1 page at a time) set
- *	the corresponding bit in the memory bitmap @bm
+ * unpack_orig_pfns - Set bits corresponding to given PFNs in a memory bitmap.
+ * @bm: Memory bitmap.
+ * @buf: Area of memory containing the PFNs.
+ *
+ * For each element of the array pointed to by @buf (1 page at a time), set the
+ * corresponding bit in @bm.
  */
 static int unpack_orig_pfns(unsigned long *buf, struct memory_bitmap *bm)
 {
@@ -2095,7 +2188,7 @@ static int unpack_orig_pfns(unsigned long *buf, struct memory_bitmap *bm)
 		/* Extract and buffer page key for data page (s390 only). */
 		page_key_memorize(buf + j);
 
-		if (memory_bm_pfn_present(bm, buf[j]))
+		if (pfn_valid(buf[j]) && memory_bm_pfn_present(bm, buf[j]))
 			memory_bm_set_bit(bm, buf[j]);
 		else
 			return -EFAULT;
@@ -2104,13 +2197,9 @@ static int unpack_orig_pfns(unsigned long *buf, struct memory_bitmap *bm)
 	return 0;
 }
 
-/* List of "safe" pages that may be used to store data loaded from the suspend
- * image
- */
-static struct linked_page *safe_pages_list;
-
 #ifdef CONFIG_HIGHMEM
-/* struct highmem_pbe is used for creating the list of highmem pages that
+/*
+ * struct highmem_pbe is used for creating the list of highmem pages that
  * should be restored atomically during the resume from disk, because the page
  * frames they have occupied before the suspend are in use.
  */
@@ -2120,7 +2209,8 @@ struct highmem_pbe {
 	struct highmem_pbe *next;
 };
 
-/* List of highmem PBEs needed for restoring the highmem pages that were
+/*
+ * List of highmem PBEs needed for restoring the highmem pages that were
  * allocated before the suspend and included in the suspend image, but have
  * also been allocated by the "resume" kernel, so their contents cannot be
  * written directly to their "original" page frames.
@@ -2128,11 +2218,11 @@ struct highmem_pbe {
 static struct highmem_pbe *highmem_pblist;
 
 /**
- *	count_highmem_image_pages - compute the number of highmem pages in the
- *	suspend image.  The bits in the memory bitmap @bm that correspond to the
- *	image pages are assumed to be set.
+ * count_highmem_image_pages - Compute the number of highmem pages in the image.
+ * @bm: Memory bitmap.
+ *
+ * The bits in @bm that correspond to image pages are assumed to be set.
  */
-
 static unsigned int count_highmem_image_pages(struct memory_bitmap *bm)
 {
 	unsigned long pfn;
@@ -2149,24 +2239,25 @@ static unsigned int count_highmem_image_pages(struct memory_bitmap *bm)
 	return cnt;
 }
 
-/**
- *	prepare_highmem_image - try to allocate as many highmem pages as
- *	there are highmem image pages (@nr_highmem_p points to the variable
- *	containing the number of highmem image pages).  The pages that are
- *	"safe" (ie. will not be overwritten when the suspend image is
- *	restored) have the corresponding bits set in @bm (it must be
- *	unitialized).
- *
- *	NOTE: This function should not be called if there are no highmem
- *	image pages.
- */
-
 static unsigned int safe_highmem_pages;
 
 static struct memory_bitmap *safe_highmem_bm;
 
-static int
-prepare_highmem_image(struct memory_bitmap *bm, unsigned int *nr_highmem_p)
+/**
+ * prepare_highmem_image - Allocate memory for loading highmem data from image.
+ * @bm: Pointer to an uninitialized memory bitmap structure.
+ * @nr_highmem_p: Pointer to the number of highmem image pages.
+ *
+ * Try to allocate as many highmem pages as there are highmem image pages
+ * (@nr_highmem_p points to the variable containing the number of highmem image
+ * pages).  The pages that are "safe" (ie. will not be overwritten when the
+ * hibernation image is restored entirely) have the corresponding bits set in
+ * @bm (it must be unitialized).
+ *
+ * NOTE: This function should not be called if there are no highmem image pages.
+ */
+static int prepare_highmem_image(struct memory_bitmap *bm,
+				 unsigned int *nr_highmem_p)
 {
 	unsigned int to_alloc;
 
@@ -2201,39 +2292,42 @@ prepare_highmem_image(struct memory_bitmap *bm, unsigned int *nr_highmem_p)
 	return 0;
 }
 
+static struct page *last_highmem_page;
+
 /**
- *	get_highmem_page_buffer - for given highmem image page find the buffer
- *	that suspend_write_next() should set for its caller to write to.
+ * get_highmem_page_buffer - Prepare a buffer to store a highmem image page.
  *
- *	If the page is to be saved to its "original" page frame or a copy of
- *	the page is to be made in the highmem, @buffer is returned.  Otherwise,
- *	the copy of the page is to be made in normal memory, so the address of
- *	the copy is returned.
+ * For a given highmem image page get a buffer that suspend_write_next() should
+ * return to its caller to write to.
  *
- *	If @buffer is returned, the caller of suspend_write_next() will write
- *	the page's contents to @buffer, so they will have to be copied to the
- *	right location on the next call to suspend_write_next() and it is done
- *	with the help of copy_last_highmem_page().  For this purpose, if
- *	@buffer is returned, @last_highmem page is set to the page to which
- *	the data will have to be copied from @buffer.
+ * If the page is to be saved to its "original" page frame or a copy of
+ * the page is to be made in the highmem, @buffer is returned.  Otherwise,
+ * the copy of the page is to be made in normal memory, so the address of
+ * the copy is returned.
+ *
+ * If @buffer is returned, the caller of suspend_write_next() will write
+ * the page's contents to @buffer, so they will have to be copied to the
+ * right location on the next call to suspend_write_next() and it is done
+ * with the help of copy_last_highmem_page().  For this purpose, if
+ * @buffer is returned, @last_highmem_page is set to the page to which
+ * the data will have to be copied from @buffer.
  */
-
-static struct page *last_highmem_page;
-
-static void *
-get_highmem_page_buffer(struct page *page, struct chain_allocator *ca)
+static void *get_highmem_page_buffer(struct page *page,
+				     struct chain_allocator *ca)
 {
 	struct highmem_pbe *pbe;
 	void *kaddr;
 
 	if (swsusp_page_is_forbidden(page) && swsusp_page_is_free(page)) {
-		/* We have allocated the "original" page frame and we can
+		/*
+		 * We have allocated the "original" page frame and we can
 		 * use it directly to store the loaded page.
 		 */
 		last_highmem_page = page;
 		return buffer;
 	}
-	/* The "original" page frame has not been allocated and we have to
+	/*
+	 * The "original" page frame has not been allocated and we have to
 	 * use a "safe" page frame to store the loaded page.
 	 */
 	pbe = chain_alloc(ca, sizeof(struct highmem_pbe));
@@ -2263,11 +2357,12 @@ get_highmem_page_buffer(struct page *page, struct chain_allocator *ca)
 }
 
 /**
- *	copy_last_highmem_page - copy the contents of a highmem image from
- *	@buffer, where the caller of snapshot_write_next() has place them,
- *	to the right location represented by @last_highmem_page .
+ * copy_last_highmem_page - Copy most the most recent highmem image page.
+ *
+ * Copy the contents of a highmem image from @buffer, where the caller of
+ * snapshot_write_next() has stored them, to the right location represented by
+ * @last_highmem_page .
  */
-
 static void copy_last_highmem_page(void)
 {
 	if (last_highmem_page) {
@@ -2294,17 +2389,13 @@ static inline void free_highmem_data(void)
 		free_image_page(buffer, PG_UNSAFE_CLEAR);
 }
 #else
-static unsigned int
-count_highmem_image_pages(struct memory_bitmap *bm) { return 0; }
+static unsigned int count_highmem_image_pages(struct memory_bitmap *bm) { return 0; }
 
-static inline int
-prepare_highmem_image(struct memory_bitmap *bm, unsigned int *nr_highmem_p)
-{
-	return 0;
-}
+static inline int prepare_highmem_image(struct memory_bitmap *bm,
+					unsigned int *nr_highmem_p) { return 0; }
 
-static inline void *
-get_highmem_page_buffer(struct page *page, struct chain_allocator *ca)
+static inline void *get_highmem_page_buffer(struct page *page,
+					    struct chain_allocator *ca)
 {
 	return ERR_PTR(-EINVAL);
 }
@@ -2314,27 +2405,27 @@ static inline int last_highmem_page_copied(void) { return 1; }
 static inline void free_highmem_data(void) {}
 #endif /* CONFIG_HIGHMEM */
 
+#define PBES_PER_LINKED_PAGE	(LINKED_PAGE_DATA_SIZE / sizeof(struct pbe))
+
 /**
- *	prepare_image - use the memory bitmap @bm to mark the pages that will
- *	be overwritten in the process of restoring the system memory state
- *	from the suspend image ("unsafe" pages) and allocate memory for the
- *	image.
+ * prepare_image - Make room for loading hibernation image.
+ * @new_bm: Unitialized memory bitmap structure.
+ * @bm: Memory bitmap with unsafe pages marked.
+ *
+ * Use @bm to mark the pages that will be overwritten in the process of
+ * restoring the system memory state from the suspend image ("unsafe" pages)
+ * and allocate memory for the image.
  *
- *	The idea is to allocate a new memory bitmap first and then allocate
- *	as many pages as needed for the image data, but not to assign these
- *	pages to specific tasks initially.  Instead, we just mark them as
- *	allocated and create a lists of "safe" pages that will be used
- *	later.  On systems with high memory a list of "safe" highmem pages is
- *	also created.
+ * The idea is to allocate a new memory bitmap first and then allocate
+ * as many pages as needed for image data, but without specifying what those
+ * pages will be used for just yet.  Instead, we mark them all as allocated and
+ * create a lists of "safe" pages to be used later.  On systems with high
+ * memory a list of "safe" highmem pages is created too.
  */
-
-#define PBES_PER_LINKED_PAGE	(LINKED_PAGE_DATA_SIZE / sizeof(struct pbe))
-
-static int
-prepare_image(struct memory_bitmap *new_bm, struct memory_bitmap *bm)
+static int prepare_image(struct memory_bitmap *new_bm, struct memory_bitmap *bm)
 {
 	unsigned int nr_pages, nr_highmem;
-	struct linked_page *sp_list, *lp;
+	struct linked_page *lp;
 	int error;
 
 	/* If there is no highmem, the buffer will not be necessary */
@@ -2342,9 +2433,7 @@ prepare_image(struct memory_bitmap *new_bm, struct memory_bitmap *bm)
 	buffer = NULL;
 
 	nr_highmem = count_highmem_image_pages(bm);
-	error = mark_unsafe_pages(bm);
-	if (error)
-		goto Free;
+	mark_unsafe_pages(bm);
 
 	error = memory_bm_create(new_bm, GFP_ATOMIC, PG_SAFE);
 	if (error)
@@ -2357,14 +2446,15 @@ prepare_image(struct memory_bitmap *new_bm, struct memory_bitmap *bm)
 		if (error)
 			goto Free;
 	}
-	/* Reserve some safe pages for potential later use.
+	/*
+	 * Reserve some safe pages for potential later use.
 	 *
 	 * NOTE: This way we make sure there will be enough safe pages for the
 	 * chain_alloc() in get_buffer().  It is a bit wasteful, but
 	 * nr_copy_pages cannot be greater than 50% of the memory anyway.
+	 *
+	 * nr_copy_pages cannot be less than allocated_unsafe_pages too.
 	 */
-	sp_list = NULL;
-	/* nr_copy_pages cannot be lesser than allocated_unsafe_pages */
 	nr_pages = nr_copy_pages - nr_highmem - allocated_unsafe_pages;
 	nr_pages = DIV_ROUND_UP(nr_pages, PBES_PER_LINKED_PAGE);
 	while (nr_pages > 0) {
@@ -2373,12 +2463,11 @@ prepare_image(struct memory_bitmap *new_bm, struct memory_bitmap *bm)
 			error = -ENOMEM;
 			goto Free;
 		}
-		lp->next = sp_list;
-		sp_list = lp;
+		lp->next = safe_pages_list;
+		safe_pages_list = lp;
 		nr_pages--;
 	}
 	/* Preallocate memory for the image */
-	safe_pages_list = NULL;
 	nr_pages = nr_copy_pages - nr_highmem - allocated_unsafe_pages;
 	while (nr_pages > 0) {
 		lp = (struct linked_page *)get_zeroed_page(GFP_ATOMIC);
@@ -2396,12 +2485,6 @@ prepare_image(struct memory_bitmap *new_bm, struct memory_bitmap *bm)
 		swsusp_set_page_free(virt_to_page(lp));
 		nr_pages--;
 	}
-	/* Free the reserved safe pages so that chain_alloc() can use them */
-	while (sp_list) {
-		lp = sp_list->next;
-		free_image_page(sp_list, PG_UNSAFE_CLEAR);
-		sp_list = lp;
-	}
 	return 0;
 
  Free:
@@ -2410,10 +2493,11 @@ prepare_image(struct memory_bitmap *new_bm, struct memory_bitmap *bm)
 }
 
 /**
- *	get_buffer - compute the address that snapshot_write_next() should
- *	set for its caller to write to.
+ * get_buffer - Get the address to store the next image data page.
+ *
+ * Get the address that snapshot_write_next() should return to its caller to
+ * write to.
  */
-
 static void *get_buffer(struct memory_bitmap *bm, struct chain_allocator *ca)
 {
 	struct pbe *pbe;
@@ -2428,12 +2512,14 @@ static void *get_buffer(struct memory_bitmap *bm, struct chain_allocator *ca)
 		return get_highmem_page_buffer(page, ca);
 
 	if (swsusp_page_is_forbidden(page) && swsusp_page_is_free(page))
-		/* We have allocated the "original" page frame and we can
+		/*
+		 * We have allocated the "original" page frame and we can
 		 * use it directly to store the loaded page.
 		 */
 		return page_address(page);
 
-	/* The "original" page frame has not been allocated and we have to
+	/*
+	 * The "original" page frame has not been allocated and we have to
 	 * use a "safe" page frame to store the loaded page.
 	 */
 	pbe = chain_alloc(ca, sizeof(struct pbe));
@@ -2450,22 +2536,21 @@ static void *get_buffer(struct memory_bitmap *bm, struct chain_allocator *ca)
 }
 
 /**
- *	snapshot_write_next - used for writing the system memory snapshot.
+ * snapshot_write_next - Get the address to store the next image page.
+ * @handle: Snapshot handle structure to guide the writing.
  *
- *	On the first call to it @handle should point to a zeroed
- *	snapshot_handle structure.  The structure gets updated and a pointer
- *	to it should be passed to this function every next time.
+ * On the first call, @handle should point to a zeroed snapshot_handle
+ * structure.  The structure gets populated then and a pointer to it should be
+ * passed to this function every next time.
  *
- *	On success the function returns a positive number.  Then, the caller
- *	is allowed to write up to the returned number of bytes to the memory
- *	location computed by the data_of() macro.
+ * On success, the function returns a positive number.  Then, the caller
+ * is allowed to write up to the returned number of bytes to the memory
+ * location computed by the data_of() macro.
  *
- *	The function returns 0 to indicate the "end of file" condition,
- *	and a negative number is returned on error.  In such cases the
- *	structure pointed to by @handle is not updated and should not be used
- *	any more.
+ * The function returns 0 to indicate the "end of file" condition.  Negative
+ * numbers are returned on errors, in which cases the structure pointed to by
+ * @handle is not updated and should not be used any more.
  */
-
 int snapshot_write_next(struct snapshot_handle *handle)
 {
 	static struct chain_allocator ca;
@@ -2491,6 +2576,8 @@ int snapshot_write_next(struct snapshot_handle *handle)
 		if (error)
 			return error;
 
+		safe_pages_list = NULL;
+
 		error = memory_bm_create(&copy_bm, GFP_ATOMIC, PG_ANY);
 		if (error)
 			return error;
@@ -2500,6 +2587,7 @@ int snapshot_write_next(struct snapshot_handle *handle)
 		if (error)
 			return error;
 
+		hibernate_restore_protection_begin();
 	} else if (handle->cur <= nr_meta_pages + 1) {
 		error = unpack_orig_pfns(buffer, &copy_bm);
 		if (error)
@@ -2522,6 +2610,7 @@ int snapshot_write_next(struct snapshot_handle *handle)
 		copy_last_highmem_page();
 		/* Restore page key for data page (s390 only). */
 		page_key_write(handle->buffer);
+		hibernate_restore_protect_page(handle->buffer);
 		handle->buffer = get_buffer(&orig_bm, &ca);
 		if (IS_ERR(handle->buffer))
 			return PTR_ERR(handle->buffer);
@@ -2533,22 +2622,23 @@ int snapshot_write_next(struct snapshot_handle *handle)
 }
 
 /**
- *	snapshot_write_finalize - must be called after the last call to
- *	snapshot_write_next() in case the last page in the image happens
- *	to be a highmem page and its contents should be stored in the
- *	highmem.  Additionally, it releases the memory that will not be
- *	used any more.
+ * snapshot_write_finalize - Complete the loading of a hibernation image.
+ *
+ * Must be called after the last call to snapshot_write_next() in case the last
+ * page in the image happens to be a highmem page and its contents should be
+ * stored in highmem.  Additionally, it recycles bitmap memory that's not
+ * necessary any more.
  */
-
 void snapshot_write_finalize(struct snapshot_handle *handle)
 {
 	copy_last_highmem_page();
 	/* Restore page key for data page (s390 only). */
 	page_key_write(handle->buffer);
 	page_key_free();
-	/* Free only if we have loaded the image entirely */
+	hibernate_restore_protect_page(handle->buffer);
+	/* Do that only if we have loaded the image entirely */
 	if (handle->cur > 1 && handle->cur > nr_meta_pages + nr_copy_pages) {
-		memory_bm_free(&orig_bm, PG_UNSAFE_CLEAR);
+		memory_bm_recycle(&orig_bm);
 		free_highmem_data();
 	}
 }
@@ -2561,8 +2651,8 @@ int snapshot_image_loaded(struct snapshot_handle *handle)
 
 #ifdef CONFIG_HIGHMEM
 /* Assumes that @buf is ready and points to a "safe" page */
-static inline void
-swap_two_pages_data(struct page *p1, struct page *p2, void *buf)
+static inline void swap_two_pages_data(struct page *p1, struct page *p2,
+				       void *buf)
 {
 	void *kaddr1, *kaddr2;
 
@@ -2576,15 +2666,15 @@ swap_two_pages_data(struct page *p1, struct page *p2, void *buf)
 }
 
 /**
- *	restore_highmem - for each highmem page that was allocated before
- *	the suspend and included in the suspend image, and also has been
- *	allocated by the "resume" kernel swap its current (ie. "before
- *	resume") contents with the previous (ie. "before suspend") one.
+ * restore_highmem - Put highmem image pages into their original locations.
+ *
+ * For each highmem page that was in use before hibernation and is included in
+ * the image, and also has been allocated by the "restore" kernel, swap its
+ * current contents with the previous (ie. "before hibernation") ones.
  *
- *	If the resume eventually fails, we can call this function once
- *	again and restore the "before resume" highmem state.
+ * If the restore eventually fails, we can call this function once again and
+ * restore the highmem state as seen by the restore kernel.
  */
-
 int restore_highmem(void)
 {
 	struct highmem_pbe *pbe = highmem_pblist;