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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * linux/kernel/power/snapshot.c
  *
  * This file provides system snapshot/restore functionality for swsusp.
  *
  * Copyright (C) 1998-2005 Pavel Machek <pavel@ucw.cz>
  * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl>
  */
 
 #define pr_fmt(fmt) "PM: hibernation: " fmt
 
 #include <linux/version.h>
 #include <linux/module.h>
 #include <linux/mm.h>
 #include <linux/suspend.h>
 #include <linux/delay.h>
 #include <linux/bitops.h>
 #include <linux/spinlock.h>
 #include <linux/kernel.h>
 #include <linux/pm.h>
 #include <linux/device.h>
 #include <linux/init.h>
 #include <linux/memblock.h>
 #include <linux/nmi.h>
 #include <linux/syscalls.h>
 #include <linux/console.h>
 #include <linux/highmem.h>
 #include <linux/list.h>
 #include <linux/slab.h>
 #include <linux/compiler.h>
 #include <linux/ktime.h>
 #include <linux/set_memory.h>
 
 #include <linux/uaccess.h>
 #include <asm/mmu_context.h>
 #include <asm/tlbflush.h>
 #include <asm/io.h>
 
 #include "power.h"
 
 #if defined(CONFIG_STRICT_KERNEL_RWX) && defined(CONFIG_ARCH_HAS_SET_MEMORY)
 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_STRICT_KERNEL_RWX  && CONFIG_ARCH_HAS_SET_MEMORY */
 
 
 /*
  * The calls to set_direct_map_*() should not fail because remapping a page
  * here means that we only update protection bits in an existing PTE.
  * It is still worth to have a warning here if something changes and this
  * will no longer be the case.
  */
 static inline void hibernate_map_page(struct page *page)
 {
     if (IS_ENABLED(CONFIG_ARCH_HAS_SET_DIRECT_MAP)) {
         int ret = set_direct_map_default_noflush(page);
 
         if (ret)
             pr_warn_once("Failed to remap page\n");
     } else {
         debug_pagealloc_map_pages(page, 1);
     }
 }
 
 static inline void hibernate_unmap_page(struct page *page)
 {
     if (IS_ENABLED(CONFIG_ARCH_HAS_SET_DIRECT_MAP)) {
         unsigned long addr = (unsigned long)page_address(page);
         int ret  = set_direct_map_invalid_noflush(page);
 
         if (ret)
             pr_warn_once("Failed to remap page\n");
 
         flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
     } else {
         debug_pagealloc_unmap_pages(page, 1);
     }
 }
 
 static int swsusp_page_is_free(struct page *);
 static void swsusp_set_page_forbidden(struct page *);
 static void swsusp_unset_page_forbidden(struct page *);
 
 /*
  * Number of bytes to reserve for memory allocations made by device drivers
  * from their ->freeze() and ->freeze_noirq() callbacks so that they don't
  * cause image creation to fail (tunable via /sys/power/reserved_size).
  */
 unsigned long reserved_size;
 
 void __init hibernate_reserved_size_init(void)
 {
     reserved_size = SPARE_PAGES * PAGE_SIZE;
 }
 
 /*
  * Preferred image size in bytes (tunable via /sys/power/image_size).
  * When it is set to N, swsusp will do its best to ensure the image
  * size will not exceed N bytes, but if that is impossible, it will
  * try to create the smallest image possible.
  */
 unsigned long image_size;
 
 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
  * 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;
 
 /* 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;
 
 /*
  * 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
 #define PG_UNSAFE_CLEAR 1
 #define PG_UNSAFE_KEEP  0
 
 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;
 
     res = (void *)get_zeroed_page(gfp_mask);
     if (safe_needed)
         while (res && swsusp_page_is_free(virt_to_page(res))) {
             /* The page is unsafe, mark it for swsusp_free() */
             swsusp_set_page_forbidden(virt_to_page(res));
             allocated_unsafe_pages++;
             res = (void *)get_zeroed_page(gfp_mask);
         }
     if (res) {
         swsusp_set_page_forbidden(virt_to_page(res));
         swsusp_set_page_free(virt_to_page(res));
     }
     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_safe_page(gfp_mask);
 }
 
 static struct page *alloc_image_page(gfp_t gfp_mask)
 {
     struct page *page;
 
     page = alloc_page(gfp_mask);
     if (page) {
         swsusp_set_page_forbidden(page);
         swsusp_set_page_free(page);
     }
     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 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;
 
     BUG_ON(!virt_addr_valid(addr));
 
     page = virt_to_page(addr);
 
     swsusp_unset_page_forbidden(page);
     if (clear_nosave_free)
         swsusp_unset_page_free(page);
 
     __free_page(page);
 }
 
 static inline void free_list_of_pages(struct linked_page *list,
                       int clear_page_nosave)
 {
     while (list) {
         struct linked_page *lp = list->next;
 
         free_image_page(list, clear_page_nosave);
         list = lp;
     }
 }
 
 /*
  * 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 */
     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)
 {
     ca->chain = NULL;
     ca->used_space = LINKED_PAGE_DATA_SIZE;
     ca->gfp_mask = gfp_mask;
     ca->safe_needed = safe_needed;
 }
 
 static void *chain_alloc(struct chain_allocator *ca, unsigned int size)
 {
     void *ret;
 
     if (LINKED_PAGE_DATA_SIZE - ca->used_space < size) {
         struct linked_page *lp;
 
         lp = ca->safe_needed ? __get_safe_page(ca->gfp_mask) :
                     get_image_page(ca->gfp_mask, PG_ANY);
         if (!lp)
             return NULL;
 
         lp->next = ca->chain;
         ca->chain = lp;
         ca->used_space = 0;
     }
     ret = ca->chain->data + ca->used_space;
     ca->used_space += size;
     return ret;
 }
 
 /*
  * Data types related to memory bitmaps.
  *
  * Memory bitmap is a structure consisting of many linked lists of
  * objects.  The main list's elements are of type struct zone_bitmap
  * and each of them corresponds 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.
  *
  * 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 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).
  *
  * 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.
  */
 
 #define BM_END_OF_MAP   (~0UL)
 
 #define BM_BITS_PER_BLOCK   (PAGE_SIZE * BITS_PER_BYTE)
 #define BM_BLOCK_SHIFT      (PAGE_SHIFT + 3)
 #define BM_BLOCK_MASK       ((1UL << BM_BLOCK_SHIFT) - 1)
 
 /*
  * struct rtree_node is a wrapper struct to link the nodes
  * of the rtree together for easy linear iteration over
  * bits and easy freeing
  */
 struct rtree_node {
     struct list_head list;
     unsigned long *data;
 };
 
 /*
  * struct mem_zone_bm_rtree represents a bitmap used for one
  * populated memory zone.
  */
 struct mem_zone_bm_rtree {
     struct list_head list;      /* Link Zones together         */
     struct list_head nodes;     /* Radix Tree inner nodes      */
     struct list_head leaves;    /* Radix Tree leaves           */
     unsigned long start_pfn;    /* Zone start page frame       */
     unsigned long end_pfn;      /* Zone end page frame + 1     */
     struct rtree_node *rtree;   /* Radix Tree Root             */
     int levels;         /* Number of Radix Tree Levels */
     unsigned int blocks;        /* Number of Bitmap Blocks     */
 };
 
 /* strcut bm_position is used for browsing memory bitmaps */
 
 struct bm_position {
     struct mem_zone_bm_rtree *zone;
     struct rtree_node *node;
     unsigned long node_pfn;
     int node_bit;
 };
 
 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 */
     struct bm_position cur; /* most recently used bit position */
 };
 
 /* Functions that operate on memory bitmaps */
 
 #define BM_ENTRIES_PER_LEVEL    (PAGE_SIZE / sizeof(unsigned long))
 #if BITS_PER_LONG == 32
 #define BM_RTREE_LEVEL_SHIFT    (PAGE_SHIFT - 2)
 #else
 #define BM_RTREE_LEVEL_SHIFT    (PAGE_SHIFT - 3)
 #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.
  * @gfp_mask: GFP mask for the allocation.
  * @safe_needed: Get pages not used before hibernation (restore only)
  * @ca: Pointer to a linked list of pages ("a chain") to allocate from
  * @list: Radix Tree node to add.
  *
  * 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,
                        struct list_head *list)
 {
     struct rtree_node *node;
 
     node = chain_alloc(ca, sizeof(struct rtree_node));
     if (!node)
         return NULL;
 
     node->data = get_image_page(gfp_mask, safe_needed);
     if (!node->data)
         return NULL;
 
     list_add_tail(&node->list, list);
 
     return node;
 }
 
 /**
  * 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.
  */
 static int add_rtree_block(struct mem_zone_bm_rtree *zone, gfp_t gfp_mask,
                int safe_needed, struct chain_allocator *ca)
 {
     struct rtree_node *node, *block, **dst;
     unsigned int levels_needed, block_nr;
     int i;
 
     block_nr = zone->blocks;
     levels_needed = 0;
 
     /* How many levels do we need for this block nr? */
     while (block_nr) {
         levels_needed += 1;
         block_nr >>= BM_RTREE_LEVEL_SHIFT;
     }
 
     /* Make sure the rtree has enough levels */
     for (i = zone->levels; i < levels_needed; i++) {
         node = alloc_rtree_node(gfp_mask, safe_needed, ca,
                     &zone->nodes);
         if (!node)
             return -ENOMEM;
 
         node->data[0] = (unsigned long)zone->rtree;
         zone->rtree = node;
         zone->levels += 1;
     }
 
     /* Allocate new block */
     block = alloc_rtree_node(gfp_mask, safe_needed, ca, &zone->leaves);
     if (!block)
         return -ENOMEM;
 
     /* Now walk the rtree to insert the block */
     node = zone->rtree;
     dst = &zone->rtree;
     block_nr = zone->blocks;
     for (i = zone->levels; i > 0; i--) {
         int index;
 
         if (!node) {
             node = alloc_rtree_node(gfp_mask, safe_needed, ca,
                         &zone->nodes);
             if (!node)
                 return -ENOMEM;
             *dst = node;
         }
 
         index = block_nr >> ((i - 1) * BM_RTREE_LEVEL_SHIFT);
         index &= BM_RTREE_LEVEL_MASK;
         dst = (struct rtree_node **)&((*dst)->data[index]);
         node = *dst;
     }
 
     zone->blocks += 1;
     *dst = block;
 
     return 0;
 }
 
 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.
  *
  * 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)
 {
     struct mem_zone_bm_rtree *zone;
     unsigned int i, nr_blocks;
     unsigned long pages;
 
     pages = end - start;
     zone  = chain_alloc(ca, sizeof(struct mem_zone_bm_rtree));
     if (!zone)
         return NULL;
 
     INIT_LIST_HEAD(&zone->nodes);
     INIT_LIST_HEAD(&zone->leaves);
     zone->start_pfn = start;
     zone->end_pfn = end;
     nr_blocks = DIV_ROUND_UP(pages, BM_BITS_PER_BLOCK);
 
     for (i = 0; i < nr_blocks; i++) {
         if (add_rtree_block(zone, gfp_mask, safe_needed, ca)) {
             free_zone_bm_rtree(zone, PG_UNSAFE_CLEAR);
             return NULL;
         }
     }
 
     return zone;
 }
 
 /**
  * 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.
  */
 static void free_zone_bm_rtree(struct mem_zone_bm_rtree *zone,
                    int clear_nosave_free)
 {
     struct rtree_node *node;
 
     list_for_each_entry(node, &zone->nodes, list)
         free_image_page(node->data, clear_nosave_free);
 
     list_for_each_entry(node, &zone->leaves, list)
         free_image_page(node->data, clear_nosave_free);
 }
 
 static void memory_bm_position_reset(struct memory_bitmap *bm)
 {
     bm->cur.zone = list_entry(bm->zones.next, struct mem_zone_bm_rtree,
                   list);
     bm->cur.node = list_entry(bm->cur.zone->leaves.next,
                   struct rtree_node, list);
     bm->cur.node_pfn = 0;
     bm->cur.node_bit = 0;
 }
 
 static void memory_bm_free(struct memory_bitmap *bm, int clear_nosave_free);
 
 struct mem_extent {
     struct list_head hook;
     unsigned long start;
     unsigned long end;
 };
 
 /**
  * free_mem_extents - Free a list of memory extents.
  * @list: List of extents to free.
  */
 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);
     }
 }
 
 /**
  * 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)
 {
     struct zone *zone;
 
     INIT_LIST_HEAD(list);
 
     for_each_populated_zone(zone) {
         unsigned long zone_start, zone_end;
         struct mem_extent *ext, *cur, *aux;
 
         zone_start = zone->zone_start_pfn;
         zone_end = zone_end_pfn(zone);
 
         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 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 list_head mem_extents;
     struct mem_extent *ext;
     int error;
 
     chain_init(&ca, gfp_mask, safe_needed);
     INIT_LIST_HEAD(&bm->zones);
 
     error = create_mem_extents(&mem_extents, gfp_mask);
     if (error)
         return error;
 
     list_for_each_entry(ext, &mem_extents, hook) {
         struct mem_zone_bm_rtree *zone;
 
         zone = create_zone_bm_rtree(gfp_mask, safe_needed, &ca,
                         ext->start, ext->end);
         if (!zone) {
             error = -ENOMEM;
             goto Error;
         }
         list_add_tail(&zone->list, &bm->zones);
     }
 
     bm->p_list = ca.chain;
     memory_bm_position_reset(bm);
  Exit:
     free_mem_extents(&mem_extents);
     return error;
 
  Error:
     bm->p_list = ca.chain;
     memory_bm_free(bm, PG_UNSAFE_CLEAR);
     goto Exit;
 }
 
 /**
  * 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;
 
     list_for_each_entry(zone, &bm->zones, list)
         free_zone_bm_rtree(zone, clear_nosave_free);
 
     free_list_of_pages(bm->p_list, clear_nosave_free);
 
     INIT_LIST_HEAD(&bm->zones);
 }
 
 /**
  * memory_bm_find_bit - Find the bit for a given PFN in a memory bitmap.
  *
  * 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)
 {
     struct mem_zone_bm_rtree *curr, *zone;
     struct rtree_node *node;
     int i, block_nr;
 
     zone = bm->cur.zone;
 
     if (pfn >= zone->start_pfn && pfn < zone->end_pfn)
         goto zone_found;
 
     zone = NULL;
 
     /* Find the right zone */
     list_for_each_entry(curr, &bm->zones, list) {
         if (pfn >= curr->start_pfn && pfn < curr->end_pfn) {
             zone = curr;
             break;
         }
     }
 
     if (!zone)
         return -EFAULT;
 
 zone_found:
     /*
      * We have found the zone. Now walk the radix tree to find the leaf node
      * for our PFN.
      */
 
     /*
      * If the zone we wish to scan is the current zone and the
      * pfn falls into the current node then we do not need to walk
      * the tree.
      */
     node = bm->cur.node;
     if (zone == bm->cur.zone &&
         ((pfn - zone->start_pfn) & ~BM_BLOCK_MASK) == bm->cur.node_pfn)
         goto node_found;
 
     node      = zone->rtree;
     block_nr  = (pfn - zone->start_pfn) >> BM_BLOCK_SHIFT;
 
     for (i = zone->levels; i > 0; i--) {
         int index;
 
         index = block_nr >> ((i - 1) * BM_RTREE_LEVEL_SHIFT);
         index &= BM_RTREE_LEVEL_MASK;
         BUG_ON(node->data[index] == 0);
         node = (struct rtree_node *)node->data[index];
     }
 
 node_found:
     /* Update last position */
     bm->cur.zone = zone;
     bm->cur.node = node;
     bm->cur.node_pfn = (pfn - zone->start_pfn) & ~BM_BLOCK_MASK;
 
     /* Set return values */
     *addr = node->data;
     *bit_nr = (pfn - zone->start_pfn) & BM_BLOCK_MASK;
 
     return 0;
 }
 
 static void memory_bm_set_bit(struct memory_bitmap *bm, unsigned long pfn)
 {
     void *addr;
     unsigned int bit;
     int error;
 
     error = memory_bm_find_bit(bm, pfn, &addr, &bit);
     BUG_ON(error);
     set_bit(bit, addr);
 }
 
 static int mem_bm_set_bit_check(struct memory_bitmap *bm, unsigned long pfn)
 {
     void *addr;
     unsigned int bit;
     int error;
 
     error = memory_bm_find_bit(bm, pfn, &addr, &bit);
     if (!error)
         set_bit(bit, addr);
 
     return error;
 }
 
 static void memory_bm_clear_bit(struct memory_bitmap *bm, unsigned long pfn)
 {
     void *addr;
     unsigned int bit;
     int error;
 
     error = memory_bm_find_bit(bm, pfn, &addr, &bit);
     BUG_ON(error);
     clear_bit(bit, addr);
 }
 
 static void memory_bm_clear_current(struct memory_bitmap *bm)
 {
     int bit;
 
     bit = max(bm->cur.node_bit - 1, 0);
     clear_bit(bit, bm->cur.node->data);
 }
 
 static int memory_bm_test_bit(struct memory_bitmap *bm, unsigned long pfn)
 {
     void *addr;
     unsigned int bit;
     int error;
 
     error = memory_bm_find_bit(bm, pfn, &addr, &bit);
     BUG_ON(error);
     return test_bit(bit, addr);
 }
 
 static bool memory_bm_pfn_present(struct memory_bitmap *bm, unsigned long pfn)
 {
     void *addr;
     unsigned int bit;
 
     return !memory_bm_find_bit(bm, pfn, &addr, &bit);
 }
 
 /*
  * rtree_next_node - Jump to the next leaf node.
  *
  * 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.
  *
  * Return true if there is a next node, false otherwise.
  */
 static bool rtree_next_node(struct memory_bitmap *bm)
 {
     if (!list_is_last(&bm->cur.node->list, &bm->cur.zone->leaves)) {
         bm->cur.node = list_entry(bm->cur.node->list.next,
                       struct rtree_node, list);
         bm->cur.node_pfn += BM_BITS_PER_BLOCK;
         bm->cur.node_bit  = 0;
         touch_softlockup_watchdog();
         return true;
     }
 
     /* No more nodes, goto next zone */
     if (!list_is_last(&bm->cur.zone->list, &bm->zones)) {
         bm->cur.zone = list_entry(bm->cur.zone->list.next,
                   struct mem_zone_bm_rtree, list);
         bm->cur.node = list_entry(bm->cur.zone->leaves.next,
                       struct rtree_node, list);
         bm->cur.node_pfn = 0;
         bm->cur.node_bit = 0;
         return true;
     }
 
     /* No more zones */
     return false;
 }
 
 /**
  * memory_bm_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 @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 for the given memory bitmap.
  */
 static unsigned long memory_bm_next_pfn(struct memory_bitmap *bm)
 {
     unsigned long bits, pfn, pages;
     int bit;
 
     do {
         pages     = bm->cur.zone->end_pfn - bm->cur.zone->start_pfn;
         bits      = min(pages - bm->cur.node_pfn, BM_BITS_PER_BLOCK);
         bit   = find_next_bit(bm->cur.node->data, bits,
                       bm->cur.node_bit);
         if (bit < bits) {
             pfn = bm->cur.zone->start_pfn + bm->cur.node_pfn + bit;
             bm->cur.node_bit = bit + 1;
             return pfn;
         }
     } while (rtree_next_node(bm));
 
     return BM_END_OF_MAP;
 }
 
 /*
  * 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;
     unsigned long end_pfn;
 };
 
 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 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)
 {
     struct nosave_region *region;
 
     if (start_pfn >= end_pfn)
         return;
 
     if (!list_empty(&nosave_regions)) {
         /* Try to extend the previous region (they should be sorted) */
         region = list_entry(nosave_regions.prev,
                     struct nosave_region, list);
         if (region->end_pfn == start_pfn) {
             region->end_pfn = end_pfn;
             goto Report;
         }
     }
     /* This allocation cannot fail */
     region = memblock_alloc(sizeof(struct nosave_region),
                 SMP_CACHE_BYTES);
     if (!region)
         panic("%s: Failed to allocate %zu bytes\n", __func__,
               sizeof(struct nosave_region));
     region->start_pfn = start_pfn;
     region->end_pfn = end_pfn;
     list_add_tail(&region->list, &nosave_regions);
  Report:
     pr_info("Registered nosave memory: [mem %#010llx-%#010llx]\n",
         (unsigned long long) start_pfn << PAGE_SHIFT,
         ((unsigned long long) end_pfn << PAGE_SHIFT) - 1);
 }
 
 /*
  * Set bits in this map correspond to the page frames the contents of which
  * should not be saved during the suspend.
  */
 static struct memory_bitmap *forbidden_pages_map;
 
 /* Set bits in this map correspond to free page frames. */
 static struct memory_bitmap *free_pages_map;
 
 /*
  * Each page frame allocated for creating the image is marked by setting the
  * corresponding bits in forbidden_pages_map and free_pages_map simultaneously
  */
 
 void swsusp_set_page_free(struct page *page)
 {
     if (free_pages_map)
         memory_bm_set_bit(free_pages_map, page_to_pfn(page));
 }
 
 static int swsusp_page_is_free(struct page *page)
 {
     return free_pages_map ?
         memory_bm_test_bit(free_pages_map, page_to_pfn(page)) : 0;
 }
 
 void swsusp_unset_page_free(struct page *page)
 {
     if (free_pages_map)
         memory_bm_clear_bit(free_pages_map, page_to_pfn(page));
 }
 
 static void swsusp_set_page_forbidden(struct page *page)
 {
     if (forbidden_pages_map)
         memory_bm_set_bit(forbidden_pages_map, page_to_pfn(page));
 }
 
 int swsusp_page_is_forbidden(struct page *page)
 {
     return forbidden_pages_map ?
         memory_bm_test_bit(forbidden_pages_map, page_to_pfn(page)) : 0;
 }
 
 static void swsusp_unset_page_forbidden(struct page *page)
 {
     if (forbidden_pages_map)
         memory_bm_clear_bit(forbidden_pages_map, page_to_pfn(page));
 }
 
 /**
  * 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;
 
     if (list_empty(&nosave_regions))
         return;
 
     list_for_each_entry(region, &nosave_regions, list) {
         unsigned long pfn;
 
         pr_debug("Marking nosave pages: [mem %#010llx-%#010llx]\n",
              (unsigned long long) region->start_pfn << PAGE_SHIFT,
              ((unsigned long long) region->end_pfn << PAGE_SHIFT)
                 - 1);
 
         for (pfn = region->start_pfn; pfn < region->end_pfn; pfn++)
             if (pfn_valid(pfn)) {
                 /*
                  * It is safe to ignore the result of
                  * mem_bm_set_bit_check() here, since we won't
                  * touch the PFNs for which the error is
                  * returned anyway.
                  */
                 mem_bm_set_bit_check(bm, pfn);
             }
     }
 }
 
 /**
  * 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;
     int error = 0;
 
     if (forbidden_pages_map && free_pages_map)
         return 0;
     else
         BUG_ON(forbidden_pages_map || free_pages_map);
 
     bm1 = kzalloc(sizeof(struct memory_bitmap), GFP_KERNEL);
     if (!bm1)
         return -ENOMEM;
 
     error = memory_bm_create(bm1, GFP_KERNEL, PG_ANY);
     if (error)
         goto Free_first_object;
 
     bm2 = kzalloc(sizeof(struct memory_bitmap), GFP_KERNEL);
     if (!bm2)
         goto Free_first_bitmap;
 
     error = memory_bm_create(bm2, GFP_KERNEL, PG_ANY);
     if (error)
         goto Free_second_object;
 
     forbidden_pages_map = bm1;
     free_pages_map = bm2;
     mark_nosave_pages(forbidden_pages_map);
 
     pr_debug("Basic memory bitmaps created\n");
 
     return 0;
 
  Free_second_object:
     kfree(bm2);
  Free_first_bitmap:
     memory_bm_free(bm1, PG_UNSAFE_CLEAR);
  Free_first_object:
     kfree(bm1);
     return -ENOMEM;
 }
 
 /**
  * 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;
 
     if (WARN_ON(!(forbidden_pages_map && free_pages_map)))
         return;
 
     bm1 = forbidden_pages_map;
     bm2 = free_pages_map;
     forbidden_pages_map = NULL;
     free_pages_map = NULL;
     memory_bm_free(bm1, PG_UNSAFE_CLEAR);
     kfree(bm1);
     memory_bm_free(bm2, PG_UNSAFE_CLEAR);
     kfree(bm2);
 
     pr_debug("Basic memory bitmaps freed\n");
 }
 
 static void clear_or_poison_free_page(struct page *page)
 {
     if (page_poisoning_enabled_static())
         __kernel_poison_pages(page, 1);
     else if (want_init_on_free())
         clear_highpage(page);
 }
 
 void clear_or_poison_free_pages(void)
 {
     struct memory_bitmap *bm = free_pages_map;
     unsigned long pfn;
 
     if (WARN_ON(!(free_pages_map)))
         return;
 
     if (page_poisoning_enabled() || want_init_on_free()) {
         memory_bm_position_reset(bm);
         pfn = memory_bm_next_pfn(bm);
         while (pfn != BM_END_OF_MAP) {
             if (pfn_valid(pfn))
                 clear_or_poison_free_page(pfn_to_page(pfn));
 
             pfn = memory_bm_next_pfn(bm);
         }
         memory_bm_position_reset(bm);
         pr_info("free pages cleared after restore\n");
     }
 }
 
 /**
  * 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;
 
     rtree = nodes = DIV_ROUND_UP(zone->spanned_pages, BM_BITS_PER_BLOCK);
     rtree += DIV_ROUND_UP(rtree * sizeof(struct rtree_node),
                   LINKED_PAGE_DATA_SIZE);
     while (nodes > 1) {
         nodes = DIV_ROUND_UP(nodes, BM_ENTRIES_PER_LEVEL);
         rtree += nodes;
     }
 
     return 2 * rtree;
 }
 
 #ifdef CONFIG_HIGHMEM
 /**
  * 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;
     unsigned int cnt = 0;
 
     for_each_populated_zone(zone)
         if (is_highmem(zone))
             cnt += zone_page_state(zone, NR_FREE_PAGES);
 
     return cnt;
 }
 
 /**
  * saveable_highmem_page - Check if a highmem page is saveable.
  *
  * 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)
 {
     struct page *page;
 
     if (!pfn_valid(pfn))
         return NULL;
 
     page = pfn_to_online_page(pfn);
     if (!page || page_zone(page) != zone)
         return NULL;
 
     BUG_ON(!PageHighMem(page));
 
     if (swsusp_page_is_forbidden(page) ||  swsusp_page_is_free(page))
         return NULL;
 
     if (PageReserved(page) || PageOffline(page))
         return NULL;
 
     if (page_is_guard(page))
         return NULL;
 
     return page;
 }
 
 /**
  * count_highmem_pages - Compute the total number of saveable highmem pages.
  */
 static unsigned int count_highmem_pages(void)
 {
     struct zone *zone;
     unsigned int n = 0;
 
     for_each_populated_zone(zone) {
         unsigned long pfn, max_zone_pfn;
 
         if (!is_highmem(zone))
             continue;
 
         mark_free_pages(zone);
         max_zone_pfn = zone_end_pfn(zone);
         for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
             if (saveable_highmem_page(zone, pfn))
                 n++;
     }
     return n;
 }
 #else
 static inline void *saveable_highmem_page(struct zone *z, unsigned long p)
 {
     return NULL;
 }
 #endif /* CONFIG_HIGHMEM */
 
 /**
  * saveable_page - Check if the given page is saveable.
  *
  * 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)
 {
     struct page *page;
 
     if (!pfn_valid(pfn))
         return NULL;
 
     page = pfn_to_online_page(pfn);
     if (!page || page_zone(page) != zone)
         return NULL;
 
     BUG_ON(PageHighMem(page));
 
     if (swsusp_page_is_forbidden(page) || swsusp_page_is_free(page))
         return NULL;
 
     if (PageOffline(page))
         return NULL;
 
     if (PageReserved(page)
         && (!kernel_page_present(page) || pfn_is_nosave(pfn)))
         return NULL;
 
     if (page_is_guard(page))
         return NULL;
 
     return page;
 }
 
 /**
  * count_data_pages - Compute the total number of saveable non-highmem pages.
  */
 static unsigned int count_data_pages(void)
 {
     struct zone *zone;
     unsigned long pfn, max_zone_pfn;
     unsigned int n = 0;
 
     for_each_populated_zone(zone) {
         if (is_highmem(zone))
             continue;
 
         mark_free_pages(zone);
         max_zone_pfn = zone_end_pfn(zone);
         for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
             if (saveable_page(zone, pfn))
                 n++;
     }
     return n;
 }
 
 /*
  * 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)
 {
     int n;
 
     for (n = PAGE_SIZE / sizeof(long); n; n--)
         *dst++ = *src++;
 }
 
 /**
  * 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 or
  * CONFIG_ARCH_HAS_SET_DIRECT_MAP is not set. In that case kernel_page_present()
  * always returns 'true'.
  */
 static void safe_copy_page(void *dst, struct page *s_page)
 {
     if (kernel_page_present(s_page)) {
         do_copy_page(dst, page_address(s_page));
     } else {
         hibernate_map_page(s_page);
         do_copy_page(dst, page_address(s_page));
         hibernate_unmap_page(s_page);
     }
 }
 
 #ifdef CONFIG_HIGHMEM
 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);
 }
 
 static void copy_data_page(unsigned long dst_pfn, unsigned long src_pfn)
 {
     struct page *s_page, *d_page;
     void *src, *dst;
 
     s_page = pfn_to_page(src_pfn);
     d_page = pfn_to_page(dst_pfn);
     if (PageHighMem(s_page)) {
         src = kmap_atomic(s_page);
         dst = kmap_atomic(d_page);
         do_copy_page(dst, src);
         kunmap_atomic(dst);
         kunmap_atomic(src);
     } else {
         if (PageHighMem(d_page)) {
             /*
              * The page pointed to by src may contain some kernel
              * data modified by kmap_atomic()
              */
             safe_copy_page(buffer, s_page);
             dst = kmap_atomic(d_page);
             copy_page(dst, buffer);
             kunmap_atomic(dst);
         } else {
             safe_copy_page(page_address(d_page), s_page);
         }
     }
 }
 #else
 #define page_is_saveable(zone, pfn) saveable_page(zone, pfn)
 
 static inline void copy_data_page(unsigned long dst_pfn, unsigned long src_pfn)
 {
     safe_copy_page(page_address(pfn_to_page(dst_pfn)),
                 pfn_to_page(src_pfn));
 }
 #endif /* CONFIG_HIGHMEM */
 
 static void copy_data_pages(struct memory_bitmap *copy_bm,
                 struct memory_bitmap *orig_bm)
 {
     struct zone *zone;
     unsigned long pfn;
 
     for_each_populated_zone(zone) {
         unsigned long max_zone_pfn;
 
         mark_free_pages(zone);
         max_zone_pfn = zone_end_pfn(zone);
         for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
             if (page_is_saveable(zone, pfn))
                 memory_bm_set_bit(orig_bm, pfn);
     }
     memory_bm_position_reset(orig_bm);
     memory_bm_position_reset(copy_bm);
     for(;;) {
         pfn = memory_bm_next_pfn(orig_bm);
         if (unlikely(pfn == BM_END_OF_MAP))
             break;
         copy_data_page(memory_bm_next_pfn(copy_bm), pfn);
     }
 }
 
 /* Total number of image pages */
 static unsigned int nr_copy_pages;
 /* Number of pages needed for saving the original pfns of the image pages */
 static unsigned int nr_meta_pages;
 /*
  * Numbers of normal and highmem page frames allocated for hibernation image
  * before suspending devices.
  */
 static unsigned int alloc_normal, alloc_highmem;
 /*
  * Memory bitmap used for marking saveable pages (during hibernation) or
  * hibernation image pages (during restore)
  */
 static struct memory_bitmap orig_bm;
 /*
  * Memory bitmap used during hibernation for marking allocated page frames that
  * will contain copies of saveable pages.  During restore it is initially used
  * for marking hibernation image pages, but then the set bits from it are
  * duplicated in @orig_bm and it is released.  On highmem systems it is next
  * used for marking "safe" highmem pages, but it has to be reinitialized for
  * this purpose.
  */
 static struct memory_bitmap copy_bm;
 
 /**
  * swsusp_free - Free pages allocated for hibernation image.
  *
  * Image pages are allocated before snapshot creation, so they need to be
  * released after resume.
  */
 void swsusp_free(void)
 {
     unsigned long fb_pfn, fr_pfn;
 
     if (!forbidden_pages_map || !free_pages_map)
         goto out;
 
     memory_bm_position_reset(forbidden_pages_map);
     memory_bm_position_reset(free_pages_map);
 
 loop:
     fr_pfn = memory_bm_next_pfn(free_pages_map);
     fb_pfn = memory_bm_next_pfn(forbidden_pages_map);
 
     /*
      * Find the next bit set in both bitmaps. This is guaranteed to
      * terminate when fb_pfn == fr_pfn == BM_END_OF_MAP.
      */
     do {
         if (fb_pfn < fr_pfn)
             fb_pfn = memory_bm_next_pfn(forbidden_pages_map);
         if (fr_pfn < fb_pfn)
             fr_pfn = memory_bm_next_pfn(free_pages_map);
     } while (fb_pfn != fr_pfn);
 
     if (fr_pfn != BM_END_OF_MAP && pfn_valid(fr_pfn)) {
         struct page *page = pfn_to_page(fr_pfn);
 
         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;
     }
 
 out:
     nr_copy_pages = 0;
     nr_meta_pages = 0;
     restore_pblist = NULL;
     buffer = NULL;
     alloc_normal = 0;
     alloc_highmem = 0;
     hibernate_restore_protection_end();
 }
 
 /* Helper functions used for the shrinking of memory. */
 
 #define GFP_IMAGE   (GFP_KERNEL | __GFP_NOWARN)
 
 /**
  * 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.
  *
  * Return value: Number of page frames actually allocated
  */
 static unsigned long preallocate_image_pages(unsigned long nr_pages, gfp_t mask)
 {
     unsigned long nr_alloc = 0;
 
     while (nr_pages > 0) {
         struct page *page;
 
         page = alloc_image_page(mask);
         if (!page)
             break;
         memory_bm_set_bit(&copy_bm, page_to_pfn(page));
         if (PageHighMem(page))
             alloc_highmem++;
         else
             alloc_normal++;
         nr_pages--;
         nr_alloc++;
     }
 
     return nr_alloc;
 }
 
 static unsigned long preallocate_image_memory(unsigned long nr_pages,
                           unsigned long avail_normal)
 {
     unsigned long alloc;
 
     if (avail_normal <= alloc_normal)
         return 0;
 
     alloc = avail_normal - alloc_normal;
     if (nr_pages < alloc)
         alloc = nr_pages;
 
     return preallocate_image_pages(alloc, GFP_IMAGE);
 }
 
 #ifdef CONFIG_HIGHMEM
 static unsigned long preallocate_image_highmem(unsigned long nr_pages)
 {
     return preallocate_image_pages(nr_pages, GFP_IMAGE | __GFP_HIGHMEM);
 }
 
 /**
  *  __fraction - Compute (an approximation of) x * (multiplier / base).
  */
 static unsigned long __fraction(u64 x, u64 multiplier, u64 base)
 {
     return div64_u64(x * multiplier, base);
 }
 
 static unsigned long preallocate_highmem_fraction(unsigned long nr_pages,
                           unsigned long highmem,
                           unsigned long total)
 {
     unsigned long alloc = __fraction(nr_pages, highmem, total);
 
     return preallocate_image_pages(alloc, GFP_IMAGE | __GFP_HIGHMEM);
 }
 #else /* CONFIG_HIGHMEM */
 static inline unsigned long preallocate_image_highmem(unsigned long nr_pages)
 {
     return 0;
 }
 
 static inline unsigned long preallocate_highmem_fraction(unsigned long nr_pages,
                              unsigned long highmem,
                              unsigned long total)
 {
     return 0;
 }
 #endif /* CONFIG_HIGHMEM */
 
 /**
  * free_unnecessary_pages - Release preallocated pages not needed for the image.
  */
 static unsigned long free_unnecessary_pages(void)
 {
     unsigned long save, to_free_normal, to_free_highmem, free;
 
     save = count_data_pages();
     if (alloc_normal >= save) {
         to_free_normal = alloc_normal - save;
         save = 0;
     } else {
         to_free_normal = 0;
         save -= alloc_normal;
     }
     save += count_highmem_pages();
     if (alloc_highmem >= save) {
         to_free_highmem = alloc_highmem - save;
     } else {
         to_free_highmem = 0;
         save -= alloc_highmem;
         if (to_free_normal > save)
             to_free_normal -= save;
         else
             to_free_normal = 0;
     }
     free = to_free_normal + to_free_highmem;
 
     memory_bm_position_reset(&copy_bm);
 
     while (to_free_normal > 0 || to_free_highmem > 0) {
         unsigned long pfn = memory_bm_next_pfn(&copy_bm);
         struct page *page = pfn_to_page(pfn);
 
         if (PageHighMem(page)) {
             if (!to_free_highmem)
                 continue;
             to_free_highmem--;
             alloc_highmem--;
         } else {
             if (!to_free_normal)
                 continue;
             to_free_normal--;
             alloc_normal--;
         }
         memory_bm_clear_bit(&copy_bm, pfn);
         swsusp_unset_page_forbidden(page);
         swsusp_unset_page_free(page);
         __free_page(page);
     }
 
     return free;
 }
 
 /**
  * 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
  * minimum acceptable size of a hibernation image to use as the lower limit for
  * preallocating memory.
  *
  * We assume that the minimum image size should be proportional to
  *
  * [number of saveable pages] - [number of pages that can be freed in theory]
  *
  * where the second term is the sum of (1) reclaimable slab pages, (2) active
  * and (3) inactive anonymous pages, (4) active and (5) inactive file pages.
  */
 static unsigned long minimum_image_size(unsigned long saveable)
 {
     unsigned long size;
 
     size = global_node_page_state_pages(NR_SLAB_RECLAIMABLE_B)
         + global_node_page_state(NR_ACTIVE_ANON)
         + global_node_page_state(NR_INACTIVE_ANON)
         + global_node_page_state(NR_ACTIVE_FILE)
         + global_node_page_state(NR_INACTIVE_FILE);
 
     return saveable <= size ? 0 : saveable - size;
 }
 
 /**
  * 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
  * hibernation for allocations made while saving the image and for device
  * drivers, in case they need to allocate memory from their hibernation
  * callbacks (these two numbers are given by PAGES_FOR_IO (which is a rough
  * estimate) and reserved_size divided by PAGE_SIZE (which is tunable through
  * /sys/power/reserved_size, respectively).  To make this happen, we compute the
  * total number of available page frames and allocate at least
  *
  * ([page frames total] + PAGES_FOR_IO + [metadata pages]) / 2
  *  + 2 * DIV_ROUND_UP(reserved_size, PAGE_SIZE)
  *
  * of them, which corresponds to the maximum size of a hibernation image.
  *
  * If image_size is set below the number following from the above formula,
  * the preallocation of memory is continued until the total number of saveable
  * pages in the system is below the requested image size or the minimum
  * acceptable image size returned by minimum_image_size(), whichever is greater.
  */
 int hibernate_preallocate_memory(void)
 {
     struct zone *zone;
     unsigned long saveable, size, max_size, count, highmem, pages = 0;
     unsigned long alloc, save_highmem, pages_highmem, avail_normal;
     ktime_t start, stop;
     int error;
 
     pr_info("Preallocating image memory\n");
     start = ktime_get();
 
     error = memory_bm_create(&orig_bm, GFP_IMAGE, PG_ANY);
     if (error) {
         pr_err("Cannot allocate original bitmap\n");
         goto err_out;
     }
 
     error = memory_bm_create(&copy_bm, GFP_IMAGE, PG_ANY);
     if (error) {
         pr_err("Cannot allocate copy bitmap\n");
         goto err_out;
     }
 
     alloc_normal = 0;
     alloc_highmem = 0;
 
     /* Count the number of saveable data pages. */
     save_highmem = count_highmem_pages();
     saveable = count_data_pages();
 
     /*
      * Compute the total number of page frames we can use (count) and the
      * number of pages needed for image metadata (size).
      */
     count = saveable;
     saveable += save_highmem;
     highmem = save_highmem;
     size = 0;
     for_each_populated_zone(zone) {
         size += snapshot_additional_pages(zone);
         if (is_highmem(zone))
             highmem += zone_page_state(zone, NR_FREE_PAGES);
         else
             count += zone_page_state(zone, NR_FREE_PAGES);
     }
     avail_normal = count;
     count += highmem;
     count -= totalreserve_pages;
 
     /* Compute the maximum number of saveable pages to leave in memory. */
     max_size = (count - (size + PAGES_FOR_IO)) / 2
             - 2 * DIV_ROUND_UP(reserved_size, PAGE_SIZE);
     /* Compute the desired number of image pages specified by image_size. */
     size = DIV_ROUND_UP(image_size, PAGE_SIZE);
     if (size > max_size)
         size = max_size;
     /*
      * If the desired number of image pages is at least as large as the
      * current number of saveable pages in memory, allocate page frames for
      * the image and we're done.
      */
     if (size >= saveable) {
         pages = preallocate_image_highmem(save_highmem);
         pages += preallocate_image_memory(saveable - pages, avail_normal);
         goto out;
     }
 
     /* Estimate the minimum size of the image. */
     pages = minimum_image_size(saveable);
     /*
      * To avoid excessive pressure on the normal zone, leave room in it to
      * accommodate an image of the minimum size (unless it's already too
      * small, in which case don't preallocate pages from it at all).
      */
     if (avail_normal > pages)
         avail_normal -= pages;
     else
         avail_normal = 0;
     if (size < pages)
         size = min_t(unsigned long, pages, max_size);
 
     /*
      * Let the memory management subsystem know that we're going to need a
      * large number of page frames to allocate and make it free some memory.
      * NOTE: If this is not done, performance will be hurt badly in some
      * test cases.
      */
     shrink_all_memory(saveable - size);
 
     /*
      * The number of saveable pages in memory was too high, so apply some
      * pressure to decrease it.  First, make room for the largest possible
      * image and fail if that doesn't work.  Next, try to decrease the size
      * of the image as much as indicated by 'size' using allocations from
      * highmem and non-highmem zones separately.
      */
     pages_highmem = preallocate_image_highmem(highmem / 2);
     alloc = count - max_size;
     if (alloc > pages_highmem)
         alloc -= pages_highmem;
     else
         alloc = 0;
     pages = preallocate_image_memory(alloc, avail_normal);
     if (pages < alloc) {
         /* We have exhausted non-highmem pages, try highmem. */
         alloc -= pages;
         pages += pages_highmem;
         pages_highmem = preallocate_image_highmem(alloc);
         if (pages_highmem < alloc) {
             pr_err("Image allocation is %lu pages short\n",
                 alloc - pages_highmem);
             goto err_out;
         }
         pages += pages_highmem;
         /*
          * size is the desired number of saveable pages to leave in
          * memory, so try to preallocate (all memory - size) pages.
          */
         alloc = (count - pages) - size;
         pages += preallocate_image_highmem(alloc);
     } else {
         /*
          * There are approximately max_size saveable pages at this point
          * and we want to reduce this number down to size.
          */
         alloc = max_size - size;
         size = preallocate_highmem_fraction(alloc, highmem, count);
         pages_highmem += size;
         alloc -= size;
         size = preallocate_image_memory(alloc, avail_normal);
         pages_highmem += preallocate_image_highmem(alloc - size);
         pages += pages_highmem + size;
     }
 
     /*
      * We only need as many page frames for the image as there are saveable
      * pages in memory, but we have allocated more.  Release the excessive
      * ones now.
      */
     pages -= free_unnecessary_pages();
 
  out:
     stop = ktime_get();
     pr_info("Allocated %lu pages for snapshot\n", pages);
     swsusp_show_speed(start, stop, pages, "Allocated");
 
     return 0;
 
  err_out:
     swsusp_free();
     return -ENOMEM;
 }
 
 #ifdef CONFIG_HIGHMEM
 /**
  * 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;
 
     if (free_highmem >= nr_highmem)
         nr_highmem = 0;
     else
         nr_highmem -= free_highmem;
 
     return nr_highmem;
 }
 #else
 static unsigned int count_pages_for_highmem(unsigned int nr_highmem) { return 0; }
 #endif /* CONFIG_HIGHMEM */
 
 /**
  * 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;
     unsigned int free = alloc_normal;
 
     for_each_populated_zone(zone)
         if (!is_highmem(zone))
             free += zone_page_state(zone, NR_FREE_PAGES);
 
     nr_pages += count_pages_for_highmem(nr_highmem);
     pr_debug("Normal pages needed: %u + %u, available pages: %u\n",
          nr_pages, PAGES_FOR_IO, free);
 
     return free > nr_pages + PAGES_FOR_IO;
 }
 
 #ifdef CONFIG_HIGHMEM
 /**
  * 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, safe_needed);
     return buffer ? 0 : -ENOMEM;
 }
 
 /**
  * alloc_highmem_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)
 {
     unsigned int to_alloc = count_free_highmem_pages();
 
     if (to_alloc > nr_highmem)
         to_alloc = nr_highmem;
 
     nr_highmem -= to_alloc;
     while (to_alloc-- > 0) {
         struct page *page;
 
         page = alloc_image_page(__GFP_HIGHMEM|__GFP_KSWAPD_RECLAIM);
         memory_bm_set_bit(bm, page_to_pfn(page));
     }
     return 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; }
 #endif /* CONFIG_HIGHMEM */
 
 /**
  * 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.
  *
  * 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 *copy_bm,
             unsigned int nr_pages, unsigned int nr_highmem)
 {
     if (nr_highmem > 0) {
         if (get_highmem_buffer(PG_ANY))
             goto err_out;
         if (nr_highmem > alloc_highmem) {
             nr_highmem -= alloc_highmem;
             nr_pages += alloc_highmem_pages(copy_bm, nr_highmem);
         }
     }
     if (nr_pages > alloc_normal) {
         nr_pages -= alloc_normal;
         while (nr_pages-- > 0) {
             struct page *page;
 
             page = alloc_image_page(GFP_ATOMIC);
             if (!page)
                 goto err_out;
             memory_bm_set_bit(copy_bm, page_to_pfn(page));
         }
     }
 
     return 0;
 
  err_out:
     swsusp_free();
     return -ENOMEM;
 }
 
 asmlinkage __visible int swsusp_save(void)
 {
     unsigned int nr_pages, nr_highmem;
 
     pr_info("Creating image:\n");
 
     drain_local_pages(NULL);
     nr_pages = count_data_pages();
     nr_highmem = count_highmem_pages();
     pr_info("Need to copy %u pages\n", nr_pages + nr_highmem);
 
     if (!enough_free_mem(nr_pages, nr_highmem)) {
         pr_err("Not enough free memory\n");
         return -ENOMEM;
     }
 
     if (swsusp_alloc(&copy_bm, nr_pages, nr_highmem)) {
         pr_err("Memory allocation failed\n");
         return -ENOMEM;
     }
 
     /*
      * During allocating of suspend pagedir, new cold pages may appear.
      * Kill them.
      */
     drain_local_pages(NULL);
     copy_data_pages(&copy_bm, &orig_bm);
 
     /*
      * End of critical section. From now on, we can write to memory,
      * but we should not touch disk. This specially means we must _not_
      * touch swap space! Except we must write out our image of course.
      */
 
     nr_pages += nr_highmem;
     nr_copy_pages = nr_pages;
     nr_meta_pages = DIV_ROUND_UP(nr_pages * sizeof(long), PAGE_SIZE);
 
     pr_info("Image created (%d pages copied)\n", nr_pages);
 
     return 0;
 }
 
 #ifndef CONFIG_ARCH_HIBERNATION_HEADER
 static int init_header_complete(struct swsusp_info *info)
 {
     memcpy(&info->uts, init_utsname(), sizeof(struct new_utsname));
     info->version_code = LINUX_VERSION_CODE;
     return 0;
 }
 
 static const char *check_image_kernel(struct swsusp_info *info)
 {
     if (info->version_code != LINUX_VERSION_CODE)
         return "kernel version";
     if (strcmp(info->uts.sysname,init_utsname()->sysname))
         return "system type";
     if (strcmp(info->uts.release,init_utsname()->release))
         return "kernel release";
     if (strcmp(info->uts.version,init_utsname()->version))
         return "version";
     if (strcmp(info->uts.machine,init_utsname()->machine))
         return "machine";
     return NULL;
 }
 #endif /* CONFIG_ARCH_HIBERNATION_HEADER */
 
 unsigned long snapshot_get_image_size(void)
 {
     return nr_copy_pages + nr_meta_pages + 1;
 }
 
 static int init_header(struct swsusp_info *info)
 {
     memset(info, 0, sizeof(struct swsusp_info));
     info->num_physpages = get_num_physpages();
     info->image_pages = nr_copy_pages;
     info->pages = snapshot_get_image_size();
     info->size = info->pages;
     info->size <<= PAGE_SHIFT;
     return init_header_complete(info);
 }
 
 /**
  * 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)
 {
     int j;
 
     for (j = 0; j < PAGE_SIZE / sizeof(long); j++) {
         buf[j] = memory_bm_next_pfn(bm);
         if (unlikely(buf[j] == BM_END_OF_MAP))
             break;
     }
 }
 
 /**
  * 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, @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.
  *
  * 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)
         return 0;
 
     if (!buffer) {
         /* This makes the buffer be freed by swsusp_free() */
         buffer = get_image_page(GFP_ATOMIC, PG_ANY);
         if (!buffer)
             return -ENOMEM;
     }
     if (!handle->cur) {
         int error;
 
         error = init_header((struct swsusp_info *)buffer);
         if (error)
             return error;
         handle->buffer = buffer;
         memory_bm_position_reset(&orig_bm);
         memory_bm_position_reset(&copy_bm);
     } else if (handle->cur <= nr_meta_pages) {
         clear_page(buffer);
         pack_pfns(buffer, &orig_bm);
     } else {
         struct page *page;
 
         page = pfn_to_page(memory_bm_next_pfn(&copy_bm));
         if (PageHighMem(page)) {
             /*
              * Highmem pages are copied to the buffer,
              * because we can't return with a kmapped
              * highmem page (we may not be called again).
              */
             void *kaddr;
 
             kaddr = kmap_atomic(page);
             copy_page(buffer, kaddr);
             kunmap_atomic(kaddr);
             handle->buffer = buffer;
         } else {
             handle->buffer = page_address(page);
         }
     }
     handle->cur++;
     return PAGE_SIZE;
 }
 
 static void duplicate_memory_bitmap(struct memory_bitmap *dst,
                     struct memory_bitmap *src)
 {
     unsigned long 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_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;
 
     /* 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_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)
 {
     const char *reason;
 
     reason = check_image_kernel(info);
     if (!reason && info->num_physpages != get_num_physpages())
         reason = "memory size";
     if (reason) {
         pr_err("Image mismatch: %s\n", reason);
         return -EPERM;
     }
     return 0;
 }
 
 /**
  * load_header - Check the image header and copy the data from it.
  */
 static int load_header(struct swsusp_info *info)
 {
     int error;
 
     restore_pblist = NULL;
     error = check_header(info);
     if (!error) {
         nr_copy_pages = info->image_pages;
         nr_meta_pages = info->pages - info->image_pages - 1;
     }
     return error;
 }
 
 /**
  * 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)
 {
     int j;
 
     for (j = 0; j < PAGE_SIZE / sizeof(long); j++) {
         if (unlikely(buf[j] == BM_END_OF_MAP))
             break;
 
         if (pfn_valid(buf[j]) && memory_bm_pfn_present(bm, buf[j]))
             memory_bm_set_bit(bm, buf[j]);
         else
             return -EFAULT;
     }
 
     return 0;
 }
 
 #ifdef CONFIG_HIGHMEM
 /*
  * 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.
  */
 struct highmem_pbe {
     struct page *copy_page; /* data is here now */
     struct page *orig_page; /* data was here before the suspend */
     struct highmem_pbe *next;
 };
 
 /*
  * 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.
  */
 static struct highmem_pbe *highmem_pblist;
 
 /**
  * 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;
     unsigned int cnt = 0;
 
     memory_bm_position_reset(bm);
     pfn = memory_bm_next_pfn(bm);
     while (pfn != BM_END_OF_MAP) {
         if (PageHighMem(pfn_to_page(pfn)))
             cnt++;
 
         pfn = memory_bm_next_pfn(bm);
     }
     return cnt;
 }
 
 static unsigned int safe_highmem_pages;
 
 static struct memory_bitmap *safe_highmem_bm;
 
 /**
  * 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 uninitialized).
  *
  * 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;
 
     if (memory_bm_create(bm, GFP_ATOMIC, PG_SAFE))
         return -ENOMEM;
 
     if (get_highmem_buffer(PG_SAFE))
         return -ENOMEM;
 
     to_alloc = count_free_highmem_pages();
     if (to_alloc > *nr_highmem_p)
         to_alloc = *nr_highmem_p;
     else
         *nr_highmem_p = to_alloc;
 
     safe_highmem_pages = 0;
     while (to_alloc-- > 0) {
         struct page *page;
 
         page = alloc_page(__GFP_HIGHMEM);
         if (!swsusp_page_is_free(page)) {
             /* The page is "safe", set its bit the bitmap */
             memory_bm_set_bit(bm, page_to_pfn(page));
             safe_highmem_pages++;
         }
         /* Mark the page as allocated */
         swsusp_set_page_forbidden(page);
         swsusp_set_page_free(page);
     }
     memory_bm_position_reset(bm);
     safe_highmem_bm = bm;
     return 0;
 }
 
 static struct page *last_highmem_page;
 
 /**
  * get_highmem_page_buffer - Prepare a buffer to store a highmem image page.
  *
  * For a given highmem image page get a buffer that suspend_write_next() should
  * return to its caller to write to.
  *
  * 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 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
          * 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
      * use a "safe" page frame to store the loaded page.
      */
     pbe = chain_alloc(ca, sizeof(struct highmem_pbe));
     if (!pbe) {
         swsusp_free();
         return ERR_PTR(-ENOMEM);
     }
     pbe->orig_page = page;
     if (safe_highmem_pages > 0) {
         struct page *tmp;
 
         /* Copy of the page will be stored in high memory */
         kaddr = buffer;
         tmp = pfn_to_page(memory_bm_next_pfn(safe_highmem_bm));
         safe_highmem_pages--;
         last_highmem_page = tmp;
         pbe->copy_page = tmp;
     } else {
         /* Copy of the page will be stored in normal memory */
         kaddr = safe_pages_list;
         safe_pages_list = safe_pages_list->next;
         pbe->copy_page = virt_to_page(kaddr);
     }
     pbe->next = highmem_pblist;
     highmem_pblist = pbe;
     return kaddr;
 }
 
 /**
  * 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) {
         void *dst;
 
         dst = kmap_atomic(last_highmem_page);
         copy_page(dst, buffer);
         kunmap_atomic(dst);
         last_highmem_page = NULL;
     }
 }
 
 static inline int last_highmem_page_copied(void)
 {
     return !last_highmem_page;
 }
 
 static inline void free_highmem_data(void)
 {
     if (safe_highmem_bm)
         memory_bm_free(safe_highmem_bm, PG_UNSAFE_CLEAR);
 
     if (buffer)
         free_image_page(buffer, PG_UNSAFE_CLEAR);
 }
 #else
 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 void *get_highmem_page_buffer(struct page *page,
                         struct chain_allocator *ca)
 {
     return ERR_PTR(-EINVAL);
 }
 
 static inline void copy_last_highmem_page(void) {}
 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 - Make room for loading hibernation image.
  * @new_bm: Uninitialized 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 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.
  */
 static int prepare_image(struct memory_bitmap *new_bm, struct memory_bitmap *bm)
 {
     unsigned int nr_pages, nr_highmem;
     struct linked_page *lp;
     int error;
 
     /* If there is no highmem, the buffer will not be necessary */
     free_image_page(buffer, PG_UNSAFE_CLEAR);
     buffer = NULL;
 
     nr_highmem = count_highmem_image_pages(bm);
     mark_unsafe_pages(bm);
 
     error = memory_bm_create(new_bm, GFP_ATOMIC, PG_SAFE);
     if (error)
         goto Free;
 
     duplicate_memory_bitmap(new_bm, bm);
     memory_bm_free(bm, PG_UNSAFE_KEEP);
     if (nr_highmem > 0) {
         error = prepare_highmem_image(bm, &nr_highmem);
         if (error)
             goto Free;
     }
     /*
      * 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.
      */
     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) {
         lp = get_image_page(GFP_ATOMIC, PG_SAFE);
         if (!lp) {
             error = -ENOMEM;
             goto Free;
         }
         lp->next = safe_pages_list;
         safe_pages_list = lp;
         nr_pages--;
     }
     /* Preallocate memory for the image */
     nr_pages = nr_copy_pages - nr_highmem - allocated_unsafe_pages;
     while (nr_pages > 0) {
         lp = (struct linked_page *)get_zeroed_page(GFP_ATOMIC);
         if (!lp) {
             error = -ENOMEM;
             goto Free;
         }
         if (!swsusp_page_is_free(virt_to_page(lp))) {
             /* The page is "safe", add it to the list */
             lp->next = safe_pages_list;
             safe_pages_list = lp;
         }
         /* Mark the page as allocated */
         swsusp_set_page_forbidden(virt_to_page(lp));
         swsusp_set_page_free(virt_to_page(lp));
         nr_pages--;
     }
     return 0;
 
  Free:
     swsusp_free();
     return error;
 }
 
 /**
  * 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;
     struct page *page;
     unsigned long pfn = memory_bm_next_pfn(bm);
 
     if (pfn == BM_END_OF_MAP)
         return ERR_PTR(-EFAULT);
 
     page = pfn_to_page(pfn);
     if (PageHighMem(page))
         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
          * use it directly to store the loaded page.
          */
         return page_address(page);
 
     /*
      * 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));
     if (!pbe) {
         swsusp_free();
         return ERR_PTR(-ENOMEM);
     }
     pbe->orig_address = page_address(page);
     pbe->address = safe_pages_list;
     safe_pages_list = safe_pages_list->next;
     pbe->next = restore_pblist;
     restore_pblist = pbe;
     return pbe->address;
 }
 
 /**
  * snapshot_write_next - Get the address to store the next image page.
  * @handle: Snapshot handle structure to guide the writing.
  *
  * 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.
  *
  * 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;
     int error = 0;
 
     /* Check if we have already loaded the entire image */
     if (handle->cur > 1 && handle->cur > nr_meta_pages + nr_copy_pages)
         return 0;
 
     handle->sync_read = 1;
 
     if (!handle->cur) {
         if (!buffer)
             /* This makes the buffer be freed by swsusp_free() */
             buffer = get_image_page(GFP_ATOMIC, PG_ANY);
 
         if (!buffer)
             return -ENOMEM;
 
         handle->buffer = buffer;
     } else if (handle->cur == 1) {
         error = load_header(buffer);
         if (error)
             return error;
 
         safe_pages_list = NULL;
 
         error = memory_bm_create(&copy_bm, GFP_ATOMIC, PG_ANY);
         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)
             return error;
 
         if (handle->cur == nr_meta_pages + 1) {
             error = prepare_image(&orig_bm, &copy_bm);
             if (error)
                 return error;
 
             chain_init(&ca, GFP_ATOMIC, PG_SAFE);
             memory_bm_position_reset(&orig_bm);
             restore_pblist = NULL;
             handle->buffer = get_buffer(&orig_bm, &ca);
             handle->sync_read = 0;
             if (IS_ERR(handle->buffer))
                 return PTR_ERR(handle->buffer);
         }
     } else {
         copy_last_highmem_page();
         hibernate_restore_protect_page(handle->buffer);
         handle->buffer = get_buffer(&orig_bm, &ca);
         if (IS_ERR(handle->buffer))
             return PTR_ERR(handle->buffer);
         if (handle->buffer != buffer)
             handle->sync_read = 0;
     }
     handle->cur++;
     return PAGE_SIZE;
 }
 
 /**
  * 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();
     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_recycle(&orig_bm);
         free_highmem_data();
     }
 }
 
 int snapshot_image_loaded(struct snapshot_handle *handle)
 {
     return !(!nr_copy_pages || !last_highmem_page_copied() ||
             handle->cur <= nr_meta_pages + nr_copy_pages);
 }
 
 #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)
 {
     void *kaddr1, *kaddr2;
 
     kaddr1 = kmap_atomic(p1);
     kaddr2 = kmap_atomic(p2);
     copy_page(buf, kaddr1);
     copy_page(kaddr1, kaddr2);
     copy_page(kaddr2, buf);
     kunmap_atomic(kaddr2);
     kunmap_atomic(kaddr1);
 }
 
 /**
  * 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 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;
     void *buf;
 
     if (!pbe)
         return 0;
 
     buf = get_image_page(GFP_ATOMIC, PG_SAFE);
     if (!buf)
         return -ENOMEM;
 
     while (pbe) {
         swap_two_pages_data(pbe->copy_page, pbe->orig_page, buf);
         pbe = pbe->next;
     }
     free_image_page(buf, PG_UNSAFE_CLEAR);
     return 0;
 }
 #endif /* CONFIG_HIGHMEM */

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