On Monday 20 July 2009, Gerald Schaefer wrote:
> From: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx>
>
> Use for_each_populated_zone() instead of for_each_zone() in hibernation
> code. This fixes a bug on s390, where we allow both config options
> HIBERNATION and MEMORY_HOTPLUG, so that we also have a ZONE_MOVABLE
> here. We only allow hibernation if no memory hotplug operation was
> performed, so in fact both features can only be used exclusively, but
> this way we don't need 2 differently configured (distribution) kernels.
>
> If we have an unpopulated ZONE_MOVABLE, we allow hibernation but run
> into a BUG_ON() in memory_bm_test/set/clear_bit() because hibernation
> code iterates through all zones, not only the populated zones, in
> several places. For example, swsusp_free() does for_each_zone() and
> then checks for pfn_valid(), which is true even if the zone is not
> populated, resulting in a BUG_ON() later because the pfn cannot be
> found in the memory bitmap.
>
> Replacing all occurences of for_each_zone() in hibernation code with
> for_each_populated_zone() would fix this issue.
Thanks for the patch, I'm going to add it to my 2.6.32 queue.
Best,
Rafael
> Signed-off-by: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx>
> ---
> kernel/power/snapshot.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> Index: linux-2.6-work/kernel/power/snapshot.c
> ===================================================================
> --- linux-2.6-work.orig/kernel/power/snapshot.c
> +++ linux-2.6-work/kernel/power/snapshot.c
> @@ -853,7 +853,7 @@ static unsigned int count_highmem_pages(
> struct zone *zone;
> unsigned int n = 0;
>
> - for_each_zone(zone) {
> + for_each_populated_zone(zone) {
> unsigned long pfn, max_zone_pfn;
>
> if (!is_highmem(zone))
> @@ -916,7 +916,7 @@ static unsigned int count_data_pages(voi
> unsigned long pfn, max_zone_pfn;
> unsigned int n = 0;
>
> - for_each_zone(zone) {
> + for_each_populated_zone(zone) {
> if (is_highmem(zone))
> continue;
>
> @@ -1010,7 +1010,7 @@ copy_data_pages(struct memory_bitmap *co
> struct zone *zone;
> unsigned long pfn;
>
> - for_each_zone(zone) {
> + for_each_populated_zone(zone) {
> unsigned long max_zone_pfn;
>
> mark_free_pages(zone);
> @@ -1046,7 +1046,7 @@ void swsusp_free(void)
> struct zone *zone;
> unsigned long pfn, max_zone_pfn;
>
> - for_each_zone(zone) {
> + for_each_populated_zone(zone) {
> max_zone_pfn = zone->zone_start_pfn + zone->spanned_pages;
> for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
> if (pfn_valid(pfn)) {
> @@ -1166,7 +1166,7 @@ static int enough_free_mem(unsigned int
> struct zone *zone;
> unsigned int free = 0, meta = 0;
>
> - for_each_zone(zone) {
> + for_each_populated_zone(zone) {
> meta += snapshot_additional_pages(zone);
> if (!is_highmem(zone))
> free += zone_page_state(zone, NR_FREE_PAGES);
> @@ -1474,7 +1474,7 @@ static int mark_unsafe_pages(struct memo
> unsigned long pfn, max_zone_pfn;
>
> /* Clear page flags */
> - for_each_zone(zone) {
> + for_each_populated_zone(zone) {
> max_zone_pfn = zone->zone_start_pfn + zone->spanned_pages;
> for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
> if (pfn_valid(pfn))
>
>
>
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