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revert "mm: fix-up zone present pages"

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Revert commit 7f1290f2f2 ("mm: fix-up zone present pages")

That patch tried to fix a issue when calculating zone->present_pages,
but it caused a regression on 32bit systems with HIGHMEM.  With that
change, reset_zone_present_pages() resets all zone->present_pages to
zero, and fixup_zone_present_pages() is called to recalculate
zone->present_pages when the boot allocator frees core memory pages into
buddy allocator.  Because highmem pages are not freed by bootmem
allocator, all highmem zones' present_pages becomes zero.

Various options for improving the situation are being discussed but for
now, let's return to the 3.6 code.

Cc: Jianguo Wu <wujianguo@huawei.com>
Cc: Jiang Liu <jiang.liu@huawei.com>
Cc: Petr Tesarik <ptesarik@suse.cz>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David Rientjes <rientjes@google.com>
Tested-by: Chris Clayton <chris2553@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrew Morton
2012-11-16 14:15:06 -08:00
committed by Linus Torvalds
parent 0f3c42f522
commit 5576646f3c
6 changed files with 1 additions and 58 deletions
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34
mm/page_alloc.c
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@@ -6098,37 +6098,3 @@ void dump_page(struct page *page)
dump_page_flags(page->flags);
mem_cgroup_print_bad_page(page);
}
/* reset zone->present_pages */
void reset_zone_present_pages(void)
{
struct zone *z;
int i, nid;
for_each_node_state(nid, N_HIGH_MEMORY) {
for (i = 0; i < MAX_NR_ZONES; i++) {
z = NODE_DATA(nid)->node_zones + i;
z->present_pages = 0;
}
}
}
/* calculate zone's present pages in buddy system */
void fixup_zone_present_pages(int nid, unsigned long start_pfn,
unsigned long end_pfn)
{
struct zone *z;
unsigned long zone_start_pfn, zone_end_pfn;
int i;
for (i = 0; i < MAX_NR_ZONES; i++) {
z = NODE_DATA(nid)->node_zones + i;
zone_start_pfn = z->zone_start_pfn;
zone_end_pfn = zone_start_pfn + z->spanned_pages;
/* if the two regions intersect */
if (!(zone_start_pfn >= end_pfn || zone_end_pfn <= start_pfn))
z->present_pages += min(end_pfn, zone_end_pfn) -
max(start_pfn, zone_start_pfn);
}
}