1 files changed, 158 insertions, 47 deletions

diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 523a451b45d3..a3a175fa0a46 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -1066,69 +1066,180 @@ void swsusp_free(void)
         buffer = NULL;
 }
 
+/* Helper functions used for the shrinking of memory. */
+
+#define GFP_IMAGE       (GFP_KERNEL | __GFP_NOWARN)
+
 /**
- *      swsusp_shrink_memory -  Try to free as much memory as needed
- *
- *      ... but do not OOM-kill anyone
+ * 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.
  *
- *      Notice: all userland should be stopped before it is called, or
- *      livelock is possible.
+ * 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) {
+                if (!alloc_image_page(mask))
+                        break;
+                nr_pages--;
+                nr_alloc++;
+        }
 
-#define SHRINK_BITE     10000
-static inline unsigned long __shrink_memory(long tmp)
+        return nr_alloc;
+}
+
+static unsigned long preallocate_image_memory(unsigned long nr_pages)
+{
+        return preallocate_image_pages(nr_pages, GFP_IMAGE);
+}
+
+#ifdef CONFIG_HIGHMEM
+static unsigned long preallocate_image_highmem(unsigned long nr_pages)
 {
-        if (tmp > SHRINK_BITE)
-                tmp = SHRINK_BITE;
-        return shrink_all_memory(tmp);
+        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)
+{
+        x *= multiplier;
+        do_div(x, base);
+        return (unsigned long)x;
+}
+
+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 */
+
+/**
+ * swsusp_shrink_memory -  Make the kernel release as much memory as needed
+ *
+ * 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 and SPARE_PAGES,
+ * respectively, both of which are rough estimates).  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 * SPARE_PAGES
+ *
+ * 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 it is impossible to
+ * allocate more memory, whichever happens first.
+ */
 int swsusp_shrink_memory(void)
 {
-        long tmp;
         struct zone *zone;
-        unsigned long pages = 0;
-        unsigned int i = 0;
-        char *p = "-\\|/";
+        unsigned long saveable, size, max_size, count, highmem, pages = 0;
+        unsigned long alloc, pages_highmem;
         struct timeval start, stop;
+        int error = 0;
 
-        printk(KERN_INFO "PM: Shrinking memory...  ");
+        printk(KERN_INFO "PM: Shrinking memory... ");
         do_gettimeofday(&start);
-        do {
-                long size, highmem_size;
-
-                highmem_size = count_highmem_pages();
-                size = count_data_pages() + PAGES_FOR_IO + SPARE_PAGES;
-                tmp = size;
-                size += highmem_size;
-                for_each_populated_zone(zone) {
-                        tmp += snapshot_additional_pages(zone);
-                        if (is_highmem(zone)) {
-                                highmem_size -=
-                                        zone_page_state(zone, NR_FREE_PAGES);
-                        } else {
-                                tmp -= zone_page_state(zone, NR_FREE_PAGES);
-                                tmp += zone->lowmem_reserve[ZONE_NORMAL];
-                        }
-                }
 
-                if (highmem_size < 0)
-                        highmem_size = 0;
+        /* Count the number of saveable data pages. */
+        highmem = count_highmem_pages();
+        saveable = count_data_pages();
 
-                tmp += highmem_size;
-                if (tmp > 0) {
-                        tmp = __shrink_memory(tmp);
-                        if (!tmp)
-                                return -ENOMEM;
-                        pages += tmp;
-                } else if (size > image_size / PAGE_SIZE) {
-                        tmp = __shrink_memory(size - (image_size / PAGE_SIZE));
-                        pages += tmp;
-                }
-                printk("\b%c", p[i++%4]);
-        } while (tmp > 0);
+        /*
+         * Compute the total number of page frames we can use (count) and the
+         * number of pages needed for image metadata (size).
+         */
+        count = saveable;
+        saveable += 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);
+        }
+        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 * SPARE_PAGES;
+        size = DIV_ROUND_UP(image_size, PAGE_SIZE);
+        if (size > max_size)
+                size = max_size;
+        /*
+         * If the maximum is not less than the current number of saveable pages
+         * in memory, we don't need to do anything more.
+         */
+        if (size >= saveable)
+                goto out;
+
+        /*
+         * 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 image_size using allocations
+         * from highmem and non-highmem zones separately.
+         */
+        pages_highmem = preallocate_image_highmem(highmem / 2);
+        alloc = (count - max_size) - pages_highmem;
+        pages = preallocate_image_memory(alloc);
+        if (pages < alloc) {
+                error = -ENOMEM;
+                goto free_out;
+        }
+        size = max_size - size;
+        alloc = size;
+        size = preallocate_highmem_fraction(size, highmem, count);
+        pages_highmem += size;
+        alloc -= size;
+        pages += preallocate_image_memory(alloc);
+        pages += pages_highmem;
+
+ free_out:
+        /* Release all of the preallocated page frames. */
+        swsusp_free();
+
+        if (error) {
+                printk(KERN_CONT "\n");
+                return error;
+        }
+
+ out:
         do_gettimeofday(&stop);
-        printk("\bdone (%lu pages freed)\n", pages);
+        printk(KERN_CONT "done (preallocated %lu free pages)\n", pages);
         swsusp_show_speed(&start, &stop, pages, "Freed");
 
         return 0;