PM/Hibernate: Move memory shrinking to snapshot.c (rev. 2)

A future patch is going to modify the memory shrinking code so that
it will make memory allocations to free memory instead of using an
artificial memory shrinking mechanism for that.  For this purpose it
is convenient to move swsusp_shrink_memory() from
kernel/power/swsusp.c to kernel/power/snapshot.c, because the new
memory-shrinking code is going to use things that are local to
kernel/power/snapshot.c .

[rev. 2: Make some functions static and remove their headers from
 kernel/power/power.h]

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Wu Fengguang <fengguang.wu@intel.com>

1 files changed, 78 insertions, 2 deletions

diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 33e2e4a819f9..523a451b45d3 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -39,6 +39,14 @@ static int swsusp_page_is_free(struct page *);
 static void swsusp_set_page_forbidden(struct page *);
 static void swsusp_unset_page_forbidden(struct page *);
 
+/*
+ * 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 = 500 * 1024 * 1024;
+
 /* 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
@@ -840,7 +848,7 @@ static struct page *saveable_highmem_page(struct zone *zone, unsigned long pfn)
  *      pages.
  */
 
-unsigned int count_highmem_pages(void)
+static unsigned int count_highmem_pages(void)
 {
         struct zone *zone;
         unsigned int n = 0;
@@ -902,7 +910,7 @@ static struct page *saveable_page(struct zone *zone, unsigned long pfn)
  *      pages.
  */
 
-unsigned int count_data_pages(void)
+static unsigned int count_data_pages(void)
 {
         struct zone *zone;
         unsigned long pfn, max_zone_pfn;
@@ -1058,6 +1066,74 @@ void swsusp_free(void)
         buffer = NULL;
 }
 
+/**
+ *      swsusp_shrink_memory -  Try to free as much memory as needed
+ *
+ *      ... but do not OOM-kill anyone
+ *
+ *      Notice: all userland should be stopped before it is called, or
+ *      livelock is possible.
+ */
+
+#define SHRINK_BITE     10000
+static inline unsigned long __shrink_memory(long tmp)
+{
+        if (tmp > SHRINK_BITE)
+                tmp = SHRINK_BITE;
+        return shrink_all_memory(tmp);
+}
+
+int swsusp_shrink_memory(void)
+{
+        long tmp;
+        struct zone *zone;
+        unsigned long pages = 0;
+        unsigned int i = 0;
+        char *p = "-\\|/";
+        struct timeval start, stop;
+
+        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;
+
+                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);
+        do_gettimeofday(&stop);
+        printk("\bdone (%lu pages freed)\n", pages);
+        swsusp_show_speed(&start, &stop, pages, "Freed");
+
+        return 0;
+}
+
 #ifdef CONFIG_HIGHMEM
 /**
   *     count_pages_for_highmem - compute the number of non-highmem pages