PM / Hibernate: fix the number of pages used for hibernate/thaw buffering

Hibernation regression fix, since 3.2.

Calculate the number of required free pages based on non-high memory
pages only, because that is where the buffers will come from.

Commit 081a9d043c983f161b78fdc4671324d1342b86bc introduced a new buffer
page allocation logic during hibernation, in order to improve the
performance. The amount of pages allocated was calculated based on total
amount of pages available, although only non-high memory pages are
usable for this purpose. This caused hibernation code to attempt to over
allocate pages on platforms that have high memory, which led to hangs.

Signed-off-by: Bojan Smojver <bojan@rexursive.com>
Signed-off-by: Rafael J. Wysocki <rjw@suse.de>

1 files changed, 22 insertions, 6 deletions

diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index 8742fd013a9..eef311a58a6 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -51,6 +51,23 @@
 
 #define MAP_PAGE_ENTRIES        (PAGE_SIZE / sizeof(sector_t) - 1)
 
+/*
+ * Number of free pages that are not high.
+ */
+static inline unsigned long low_free_pages(void)
+{
+        return nr_free_pages() - nr_free_highpages();
+}
+
+/*
+ * Number of pages required to be kept free while writing the image. Always
+ * half of all available low pages before the writing starts.
+ */
+static inline unsigned long reqd_free_pages(void)
+{
+        return low_free_pages() / 2;
+}
+
 struct swap_map_page {
         sector_t entries[MAP_PAGE_ENTRIES];
         sector_t next_swap;
@@ -72,7 +89,7 @@ struct swap_map_handle {
         sector_t cur_swap;
         sector_t first_sector;
         unsigned int k;
-        unsigned long nr_free_pages, written;
+        unsigned long reqd_free_pages;
         u32 crc32;
 };
 
@@ -316,8 +333,7 @@ static int get_swap_writer(struct swap_map_handle *handle)
                 goto err_rel;
         }
         handle->k = 0;
-        handle->nr_free_pages = nr_free_pages() >> 1;
-        handle->written = 0;
+        handle->reqd_free_pages = reqd_free_pages();
         handle->first_sector = handle->cur_swap;
         return 0;
 err_rel:
@@ -352,11 +368,11 @@ static int swap_write_page(struct swap_map_handle *handle, void *buf,
                 handle->cur_swap = offset;
                 handle->k = 0;
         }
-        if (bio_chain && ++handle->written > handle->nr_free_pages) {
+        if (bio_chain && low_free_pages() <= handle->reqd_free_pages) {
                 error = hib_wait_on_bio_chain(bio_chain);
                 if (error)
                         goto out;
-                handle->written = 0;
+                handle->reqd_free_pages = reqd_free_pages();
         }
  out:
         return error;
@@ -618,7 +634,7 @@ static int save_image_lzo(struct swap_map_handle *handle,
          * Adjust number of free pages after all allocations have been done.
          * We don't want to run out of pages when writing.
          */
-        handle->nr_free_pages = nr_free_pages() >> 1;
+        handle->reqd_free_pages = reqd_free_pages();
 
         /*
          * Start the CRC32 thread.