mm: fix free_all_bootmem_core alignment check

The check for node_boot_start is bogus because we start freeing at the
corresponding pfn.  So check if the pfn is properly aligned instead in a more
readable way and adjust the documentation.

Also remove an unneeded accounting variable.

Signed-off-by: Johannes Weiner <hannes@saeurebad.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 11 deletions

diff --git a/mm/bootmem.c b/mm/bootmem.c
index 35b3cb667036..319a79bce7cd 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -377,7 +377,7 @@ static unsigned long __init free_all_bootmem_core(pg_data_t *pgdat)
         struct page *page;
         unsigned long pfn;
         bootmem_data_t *bdata = pgdat->bdata;
-        unsigned long i, count, total = 0;
+        unsigned long i, count;
         unsigned long idx;
         unsigned long *map; 
         int gofast = 0;
@@ -389,10 +389,13 @@ static unsigned long __init free_all_bootmem_core(pg_data_t *pgdat)
         pfn = PFN_DOWN(bdata->node_boot_start);
         idx = bdata->node_low_pfn - pfn;
         map = bdata->node_bootmem_map;
-        /* Check physaddr is O(LOG2(BITS_PER_LONG)) page aligned */
-        if (bdata->node_boot_start == 0 ||
-            ffs(bdata->node_boot_start) - PAGE_SHIFT > ffs(BITS_PER_LONG))
+        /*
+         * Check if we are aligned to BITS_PER_LONG pages.  If so, we might
+         * be able to free page orders of that size at once.
+         */
+        if (!(pfn & (BITS_PER_LONG-1)))
                 gofast = 1;
+
         for (i = 0; i < idx; ) {
                 unsigned long v = ~map[i / BITS_PER_LONG];
 
@@ -420,23 +423,19 @@ static unsigned long __init free_all_bootmem_core(pg_data_t *pgdat)
                 }
                 pfn += BITS_PER_LONG;
         }
-        total += count;
 
         /*
          * Now free the allocator bitmap itself, it's not
          * needed anymore:
          */
         page = virt_to_page(bdata->node_bootmem_map);
-        count = 0;
         idx = (get_mapsize(bdata) + PAGE_SIZE-1) >> PAGE_SHIFT;
-        for (i = 0; i < idx; i++, page++) {
+        for (i = 0; i < idx; i++, page++)
                 __free_pages_bootmem(page, 0);
-                count++;
-        }
-        total += count;
+        count += i;
         bdata->node_bootmem_map = NULL;
 
-        return total;
+        return count;
 }
 
 unsigned long __init init_bootmem_node(pg_data_t *pgdat, unsigned long freepfn,