The patch titled
mm: check if any page in a pageblock is reserved before marking it MIGRATE_RESERVE
has been added to the -mm tree. Its filename is
mm-check-if-any-page-in-a-pageblock-is-reserved-before-marking-it-migrate_reserve.patch
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------------------------------------------------------
Subject: mm: check if any page in a pageblock is reserved before marking it MIGRATE_RESERVE
From: Arve Hjønnevåg <arve@xxxxxxxxxxx>
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: John Stultz <john.stultz@xxxxxxxxxx>
Cc: Dave Hansen <dave@xxxxxxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Arve Hjønnevåg <arve@xxxxxxxxxxx>
Acked-by: Mel Gorman <mel@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff -puN mm/page_alloc.c~mm-check-if-any-page-in-a-pageblock-is-reserved-before-marking-it-migrate_reserve mm/page_alloc.c
--- a/mm/page_alloc.c~mm-check-if-any-page-in-a-pageblock-is-reserved-before-marking-it-migrate_reserve
+++ a/mm/page_alloc.c
@@ -3287,6 +3287,20 @@ 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 min_wmark_pages(zone). The memory within
* the reserve will tend to store contiguous free pages. Setting min_free_kbytes
@@ -3325,7 +3339,7 @@ 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);
_
Patches currently in -mm which might be from arve@xxxxxxxxxxx are
mm-check-if-any-page-in-a-pageblock-is-reserved-before-marking-it-migrate_reserve.patch
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