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From a4eb204a8029320c2dd748daf4f51fd48d337c3d Mon Sep 17 00:00:00 2001
From: =?utf-8?q?Arve=20Hj=C3=B8nnev=C3=A5g?= <arve@android.com>
Date: Wed, 18 Mar 2009 17:27:31 -0700
Subject: [PATCH 056/134] mm: Check if any page in a pageblock is reserved before marking it MIGRATE_RESERVE
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.
---
mm/page_alloc.c | 16 +++++++++++++++-
1 files changed, 15 insertions(+), 1 deletions(-)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2570,6 +2570,20 @@ static inline unsigned long wait_table_b
#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 (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 zone->pages_min. The memory within the
* reserve will tend to store contiguous free pages. Setting min_free_kbytes
@@ -2598,7 +2612,7 @@ static void setup_zone_migrate_reserve(s
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);
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