PM / hibernate: Simplify mark_unsafe_pages()

Rework mark_unsafe_pages() to use a simpler method of clearing
all bits in free_pages_map and to set the bits for the "unsafe"
pages (ie. pages that were used by the image kernel before
hibernation) with the help of duplicate_memory_bitmap().

For this purpose, move the pfn_valid() check from mark_unsafe_pages()
to unpack_orig_pfns() where the "unsafe" pages are discovered.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 25 insertions, 39 deletions

diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index d9476ff877b8..39bbad5fac5a 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -2019,53 +2019,41 @@ int snapshot_read_next(struct snapshot_handle *handle)
         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 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 mark_unsafe_pages(struct memory_bitmap *bm)
 {
-        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));
+        /* 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" */
-        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);
+        /* Mark pages that correspond to the "original" PFNs as "unsafe" */
+        duplicate_memory_bitmap(free_pages_map, bm);
 
         allocated_unsafe_pages = 0;
-
-        return 0;
-}
-
-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);
-        }
 }
 
 static int check_header(struct swsusp_info *info)
@@ -2115,7 +2103,7 @@ 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;
@@ -2357,9 +2345,7 @@ 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)