mm, page_alloc: avoid unnecessary zone lookups during pageblock operations

Pageblocks have an associated bitmap to store migrate types and whether
the pageblock should be skipped during compaction.  The bitmap may be
associated with a memory section or a zone but the zone is looked up
unconditionally.  The compiler should optimise this away automatically
so this is a cosmetic patch only in many cases.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8f6b6eab074fa729c18d4c96806e0398f9e696a4..7f328cfb137d8bd0f1e886020bd26008bf7a5f7d 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6767,23 +6767,23 @@ void *__init alloc_large_system_hash(const char *tablename,
 }
 
 /* Return a pointer to the bitmap storing bits affecting a block of pages */
-static inline unsigned long *get_pageblock_bitmap(struct zone *zone,
+static inline unsigned long *get_pageblock_bitmap(struct page *page,
                                                        unsigned long pfn)
 {
 #ifdef CONFIG_SPARSEMEM
        return __pfn_to_section(pfn)->pageblock_flags;
 #else
-       return zone->pageblock_flags;
+       return page_zone(page)->pageblock_flags;
 #endif /* CONFIG_SPARSEMEM */
 }
 
-static inline int pfn_to_bitidx(struct zone *zone, unsigned long pfn)
+static inline int pfn_to_bitidx(struct page *page, unsigned long pfn)
 {
 #ifdef CONFIG_SPARSEMEM
        pfn &= (PAGES_PER_SECTION-1);
        return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
 #else
-       pfn = pfn - round_down(zone->zone_start_pfn, pageblock_nr_pages);
+       pfn = pfn - round_down(page_zone(page)->zone_start_pfn, pageblock_nr_pages);
        return (pfn >> pageblock_order) * NR_PAGEBLOCK_BITS;
 #endif /* CONFIG_SPARSEMEM */
 }
@@ -6801,14 +6801,12 @@ unsigned long get_pfnblock_flags_mask(struct page *page, unsigned long pfn,
                                        unsigned long end_bitidx,
                                        unsigned long mask)
 {
-       struct zone *zone;
        unsigned long *bitmap;
        unsigned long bitidx, word_bitidx;
        unsigned long word;
 
-       zone = page_zone(page);
-       bitmap = get_pageblock_bitmap(zone, pfn);
-       bitidx = pfn_to_bitidx(zone, pfn);
+       bitmap = get_pageblock_bitmap(page, pfn);
+       bitidx = pfn_to_bitidx(page, pfn);
        word_bitidx = bitidx / BITS_PER_LONG;
        bitidx &= (BITS_PER_LONG-1);
 
@@ -6830,20 +6828,18 @@ void set_pfnblock_flags_mask(struct page *page, unsigned long flags,
                                        unsigned long end_bitidx,
                                        unsigned long mask)
 {
-       struct zone *zone;
        unsigned long *bitmap;
        unsigned long bitidx, word_bitidx;
        unsigned long old_word, word;
 
        BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4);
 
-       zone = page_zone(page);
-       bitmap = get_pageblock_bitmap(zone, pfn);
-       bitidx = pfn_to_bitidx(zone, pfn);
+       bitmap = get_pageblock_bitmap(page, pfn);
+       bitidx = pfn_to_bitidx(page, pfn);
        word_bitidx = bitidx / BITS_PER_LONG;
        bitidx &= (BITS_PER_LONG-1);
 
-       VM_BUG_ON_PAGE(!zone_spans_pfn(zone, pfn), page);
+       VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page);
 
        bitidx += end_bitidx;
        mask <<= (BITS_PER_LONG - bitidx - 1);