[68/80] PM / Hibernate: Avoid hitting OOM during preallocation of memory

Greg KH
2010-09-24T16:31:45Z

From: Rafael J. Wysocki <rjw@sisk.pl>

commit 6715045ddc7472a22be5e49d4047d2d89b391f45 upstream.

There is a problem in hibernate_preallocate_memory() that it calls
preallocate_image_memory() with an argument that may be greater than
the total number of available non-highmem memory pages. If that's
the case, the OOM condition is guaranteed to trigger, which in turn
can cause significant slowdown to occur during hibernation.

To avoid that, make preallocate_image_memory() adjust its argument
before calling preallocate_image_pages(), so that the total number of
saveable non-highem pages left is not less than the minimum size of
a hibernation image. Change hibernate_preallocate_memory() to try to
allocate from highmem if the number of pages allocated by
preallocate_image_memory() is too low.

Modify free_unnecessary_pages() to take all possible memory
allocation patterns into account.

Reported-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Tested-by: M. Vefa Bicakci <bicave@superonline.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
kernel/power/snapshot.c | 85 ++++++++++++++++++++++++++++++++++++------------
1 file changed, 65 insertions(+), 20 deletions(-)

--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -1121,9 +1121,19 @@ static unsigned long preallocate_image_p
return nr_alloc;
}

-static unsigned long preallocate_image_memory(unsigned long nr_pages)
+static unsigned long preallocate_image_memory(unsigned long nr_pages,
+ unsigned long avail_normal)
{
- return preallocate_image_pages(nr_pages, GFP_IMAGE);
+ unsigned long alloc;
+
+ if (avail_normal <= alloc_normal)
+ return 0;
+
+ alloc = avail_normal - alloc_normal;
+ if (nr_pages < alloc)
+ alloc = nr_pages;
+
+ return preallocate_image_pages(alloc, GFP_IMAGE);
}

#ifdef CONFIG_HIGHMEM
@@ -1169,15 +1179,22 @@ static inline unsigned long preallocate_
*/
static void free_unnecessary_pages(void)
{
- unsigned long save_highmem, to_free_normal, to_free_highmem;
+ unsigned long save, to_free_normal, to_free_highmem;

- to_free_normal = alloc_normal - count_data_pages();
- save_highmem = count_highmem_pages();
- if (alloc_highmem > save_highmem) {
- to_free_highmem = alloc_highmem - save_highmem;
+ save = count_data_pages();
+ if (alloc_normal >= save) {
+ to_free_normal = alloc_normal - save;
+ save = 0;
+ } else {
+ to_free_normal = 0;
+ save -= alloc_normal;
+ }
+ save += count_highmem_pages();
+ if (alloc_highmem >= save) {
+ to_free_highmem = alloc_highmem - save;
} else {
to_free_highmem = 0;
- to_free_normal -= save_highmem - alloc_highmem;
+ to_free_normal -= save - alloc_highmem;
}

memory_bm_position_reset(&copy_bm);
@@ -1258,7 +1275,7 @@ int hibernate_preallocate_memory(void)
{
struct zone *zone;
unsigned long saveable, size, max_size, count, highmem, pages = 0;
- unsigned long alloc, save_highmem, pages_highmem;
+ unsigned long alloc, save_highmem, pages_highmem, avail_normal;
struct timeval start, stop;
int error;

@@ -1295,6 +1312,7 @@ int hibernate_preallocate_memory(void)
else
count += zone_page_state(zone, NR_FREE_PAGES);
}
+ avail_normal = count;
count += highmem;
count -= totalreserve_pages;

@@ -1309,12 +1327,21 @@ int hibernate_preallocate_memory(void)
*/
if (size >= saveable) {
pages = preallocate_image_highmem(save_highmem);
- pages += preallocate_image_memory(saveable - pages);
+ pages += preallocate_image_memory(saveable - pages, avail_normal);
goto out;
}

/* Estimate the minimum size of the image. */
pages = minimum_image_size(saveable);
+ /*
+ * To avoid excessive pressure on the normal zone, leave room in it to
+ * accommodate an image of the minimum size (unless it's already too
+ * small, in which case don't preallocate pages from it at all).
+ */
+ if (avail_normal > pages)
+ avail_normal -= pages;
+ else
+ avail_normal = 0;
if (size < pages)
size = min_t(unsigned long, pages, max_size);

@@ -1335,16 +1362,34 @@ int hibernate_preallocate_memory(void)
*/
pages_highmem = preallocate_image_highmem(highmem / 2);
alloc = (count - max_size) - pages_highmem;
- pages = preallocate_image_memory(alloc);
- if (pages < alloc)
- goto err_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;
+ pages = preallocate_image_memory(alloc, avail_normal);
+ if (pages < alloc) {
+ /* We have exhausted non-highmem pages, try highmem. */
+ alloc -= pages;
+ pages += pages_highmem;
+ pages_highmem = preallocate_image_highmem(alloc);
+ if (pages_highmem < alloc)
+ goto err_out;
+ pages += pages_highmem;
+ /*
+ * size is the desired number of saveable pages to leave in
+ * memory, so try to preallocate (all memory - size) pages.
+ */
+ alloc = (count - pages) - size;
+ pages += preallocate_image_highmem(alloc);
+ } else {
+ /*
+ * There are approximately max_size saveable pages at this point
+ * and we want to reduce this number down to size.
+ */
+ alloc = max_size - size;
+ size = preallocate_highmem_fraction(alloc, highmem, count);
+ pages_highmem += size;
+ alloc -= size;
+ size = preallocate_image_memory(alloc, avail_normal);
+ pages_highmem += preallocate_image_highmem(alloc - size);
+ pages += pages_highmem + size;
+ }

/*
* We only need as many page frames for the image as there are saveable