Hibernation: Handle DEBUG_PAGEALLOC on x86

Make hibernation work with CONFIG_DEBUG_PAGEALLOC set on x86, by
checking if the pages to be copied are marked as present in the
kernel mapping and temporarily marking them as present if that's not
the case.  No functional modifications are introduced if
CONFIG_DEBUG_PAGEALLOC is unset.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 29 insertions, 13 deletions

diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 95250d7c8d91..72a020cabb4c 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -875,8 +875,8 @@ static inline void *saveable_highmem_page(unsigned long pfn) { return NULL; }
 #endif /* CONFIG_HIGHMEM */
 
 /**
- *      saveable - Determine whether a non-highmem page should be included in
- *      the suspend image.
+ *      saveable_page - Determine whether a non-highmem page should be included
+ *      in the suspend 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 a part of
@@ -897,7 +897,8 @@ static struct page *saveable_page(unsigned long pfn)
         if (swsusp_page_is_forbidden(page) || swsusp_page_is_free(page))
                 return NULL;
 
-        if (PageReserved(page) && pfn_is_nosave(pfn))
+        if (PageReserved(page)
+            && (!kernel_page_present(page) || pfn_is_nosave(pfn)))
                 return NULL;
 
         return page;
@@ -938,6 +939,25 @@ 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').
+ */
+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 {
+                kernel_map_pages(s_page, 1, 1);
+                do_copy_page(dst, page_address(s_page));
+                kernel_map_pages(s_page, 1, 0);
+        }
+}
+
+
 #ifdef CONFIG_HIGHMEM
 static inline struct page *
 page_is_saveable(struct zone *zone, unsigned long pfn)
@@ -946,8 +966,7 @@ page_is_saveable(struct zone *zone, unsigned long pfn)
                         saveable_highmem_page(pfn) : saveable_page(pfn);
 }
 
-static inline void
-copy_data_page(unsigned long dst_pfn, unsigned long src_pfn)
+static void copy_data_page(unsigned long dst_pfn, unsigned long src_pfn)
 {
         struct page *s_page, *d_page;
         void *src, *dst;
@@ -961,29 +980,26 @@ copy_data_page(unsigned long dst_pfn, unsigned long src_pfn)
                 kunmap_atomic(src, KM_USER0);
                 kunmap_atomic(dst, KM_USER1);
         } else {
-                src = page_address(s_page);
                 if (PageHighMem(d_page)) {
                         /* Page pointed to by src may contain some kernel
                          * data modified by kmap_atomic()
                          */
-                        do_copy_page(buffer, src);
+                        safe_copy_page(buffer, s_page);
                         dst = kmap_atomic(pfn_to_page(dst_pfn), KM_USER0);
                         memcpy(dst, buffer, PAGE_SIZE);
                         kunmap_atomic(dst, KM_USER0);
                 } else {
-                        dst = page_address(d_page);
-                        do_copy_page(dst, src);
+                        safe_copy_page(page_address(d_page), s_page);
                 }
         }
 }
 #else
 #define page_is_saveable(zone, pfn)     saveable_page(pfn)
 
-static inline void
-copy_data_page(unsigned long dst_pfn, unsigned long src_pfn)
+static inline void copy_data_page(unsigned long dst_pfn, unsigned long src_pfn)
 {
-        do_copy_page(page_address(pfn_to_page(dst_pfn)),
-                        page_address(pfn_to_page(src_pfn)));
+        safe_copy_page(page_address(pfn_to_page(dst_pfn)),
+                                pfn_to_page(src_pfn));
 }
 #endif /* CONFIG_HIGHMEM */