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From: Arve Hjønnevåg on 5 Apr 2010 23:20
This fixes a problem where the first pageblock got marked MIGRATE_RESERVE even
though it only had a few free pages. This in turn caused no contiguous memory
to be reserved and frequent kswapd wakeups that emptied the caches to get more
contiguous memory.

Signed-off-by: Arve Hjønnevåg <arve(a)android.com>
---
mm/page_alloc.c | 16 +++++++++++++++-
1 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index fb7df1d..46ade16 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2860,6 +2860,20 @@ static inline unsigned long wait_table_bits(unsigned long size)
#define LONG_ALIGN(x) (((x)+(sizeof(long))-1)&~((sizeof(long))-1))

/*
+ * Check if a pageblock contains reserved pages
+ */
+static int pageblock_is_reserved(unsigned long start_pfn)
+{
+ unsigned long end_pfn = start_pfn + pageblock_nr_pages;
+ unsigned long pfn;
+
+ for (pfn = start_pfn; pfn < end_pfn; pfn++)
+ if (!pfn_valid_within(pfn) || PageReserved(pfn_to_page(pfn)))
+ return 1;
+ return 0;
+}
+
+/*
* Mark a number of pageblocks as MIGRATE_RESERVE. The number
* of blocks reserved is based on min_wmark_pages(zone). The memory within
* the reserve will tend to store contiguous free pages. Setting min_free_kbytes
@@ -2898,7 +2912,7 @@ static void setup_zone_migrate_reserve(struct zone *zone)
continue;

/* Blocks with reserved pages will never free, skip them. */
- if (PageReserved(page))
+ if (pageblock_is_reserved(pfn))
continue;

block_migratetype = get_pageblock_migratetype(page);
--
1.6.5.1

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Prev: [PATCH 2/4]-V3 Make room for other tps6507x drivers to have board specific initialization data.
Next: IIO: struct iio_dev_attr should be defined as static.