The patch titled
add pfn_valid_within helper for sub-MAX_ORDER hole detection
has been added to the -mm tree. Its filename is
add-pfn_valid_within-helper-for-sub-max_order-hole-detection.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: add pfn_valid_within helper for sub-MAX_ORDER hole detection
From: Andy Whitcroft <apw@xxxxxxxxxxxx>
Generally we work under the assumption that memory the mem_map array is
contigious and valid out to MAX_ORDER_NR_PAGES block of pages, ie. that if we
have validated any page within this MAX_ORDER_NR_PAGES block we need not check
any other. This is not true when CONFIG_HOLES_IN_ZONE is set and we must
check each and every reference we make from a pfn.
Add a pfn_valid_within() helper which should be used when scanning pages
within a MAX_ORDER_NR_PAGES block when we have already checked the validility
of the block normally with pfn_valid(). This can then be optimised away when
we do not have holes within a MAX_ORDER_NR_PAGES block of pages.
Signed-off-by: Andy Whitcroft <apw@xxxxxxxxxxxx>
Acked-by: Mel Gorman <mel@xxxxxxxxx>
Acked-by: Bob Picco <bob.picco@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mmzone.h | 12 ++++++++++++
mm/page_alloc.c | 8 ++------
2 files changed, 14 insertions(+), 6 deletions(-)
diff -puN include/linux/mmzone.h~add-pfn_valid_within-helper-for-sub-max_order-hole-detection include/linux/mmzone.h
--- a/include/linux/mmzone.h~add-pfn_valid_within-helper-for-sub-max_order-hole-detection
+++ a/include/linux/mmzone.h
@@ -832,6 +832,18 @@ void sparse_init(void);
void memory_present(int nid, unsigned long start, unsigned long end);
unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long);
+/*
+ * If it is possible to have holes within a MAX_ORDER_NR_PAGES, then we
+ * need to check pfn validility within that MAX_ORDER_NR_PAGES block.
+ * pfn_valid_within() should be used in this case; we optimise this away
+ * when we have no holes within a MAX_ORDER_NR_PAGES block.
+ */
+#ifdef CONFIG_HOLES_IN_ZONE
+#define pfn_valid_within(pfn) pfn_valid(pfn)
+#else
+#define pfn_valid_within(pfn) (1)
+#endif
+
#endif /* !__ASSEMBLY__ */
#endif /* __KERNEL__ */
#endif /* _LINUX_MMZONE_H */
diff -puN mm/page_alloc.c~add-pfn_valid_within-helper-for-sub-max_order-hole-detection mm/page_alloc.c
--- a/mm/page_alloc.c~add-pfn_valid_within-helper-for-sub-max_order-hole-detection
+++ a/mm/page_alloc.c
@@ -206,10 +206,8 @@ static int page_outside_zone_boundaries(
static int page_is_consistent(struct zone *zone, struct page *page)
{
-#ifdef CONFIG_HOLES_IN_ZONE
- if (!pfn_valid(page_to_pfn(page)))
+ if (!pfn_valid_within(page_to_pfn(page)))
return 0;
-#endif
if (zone != page_zone(page))
return 0;
@@ -396,10 +394,8 @@ __find_combined_index(unsigned long page
static inline int page_is_buddy(struct page *page, struct page *buddy,
int order)
{
-#ifdef CONFIG_HOLES_IN_ZONE
- if (!pfn_valid(page_to_pfn(buddy)))
+ if (!pfn_valid_within(page_to_pfn(buddy)))
return 0;
-#endif
if (page_zone_id(page) != page_zone_id(buddy))
return 0;
_
Patches currently in -mm which might be from apw@xxxxxxxxxxxx are
pci-device-ensure-sysdata-initialised-v2.patch
move-free-pages-between-lists-on-steal-fix.patch
fix-corruption-of-memmap-on-ia64-sparsemem-when-mem_section-is-not-a-power-of-2.patch
lumpy-reclaim-v4.patch
lumpy-back-out-removal-of-active-check-in-isolate_lru_pages.patch
lumpy-only-count-taken-pages-as-scanned.patch
add-pfn_valid_within-helper-for-sub-max_order-hole-detection.patch
anti-fragmentation-switch-over-to-pfn_valid_within.patch
lumpy-move-to-using-pfn_valid_within.patch
bias-the-location-of-pages-freed-for-min_free_kbytes-in-the-same-max_order_nr_pages-blocks.patch
bias-the-location-of-pages-freed-for-min_free_kbytes-in-the-same-max_order_nr_pages-blocks-tidy.patch
-
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