mm/compaction: correct the comments of compact_defer_shift

There is no compact_defer_limit. It should be compact_defer_shift in
use. and add compact_order_failed explanation.

Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Link: http://lkml.kernel.org/r/3bd60e1b-a74e-050d-ade4-6e8f54e00b92@linux.alibaba.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index efbd95dd3bbffa3f15a69a4aa24446ccabbe9c46..8379432f4f2ff119d5b3535be2545d34ed89ce34 100644 (file)
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -536,6 +536,7 @@ struct zone {
         * On compaction failure, 1<<compact_defer_shift compactions
         * are skipped before trying again. The number attempted since
         * last failure is tracked with compact_considered.
+        * compact_order_failed is the minimum compaction failed order.
         */
        unsigned int            compact_considered;
        unsigned int            compact_defer_shift;

diff --git a/mm/compaction.c b/mm/compaction.c
index b7d433f1706a72568e62875879872b8464da8460..5e8f2e22b73ed7b5a17c53f3339f83097dffddfd 100644 (file)
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -154,7 +154,7 @@ EXPORT_SYMBOL(__ClearPageMovable);
 
 /*
  * Compaction is deferred when compaction fails to result in a page
- * allocation success. 1 << compact_defer_limit compactions are skipped up
+ * allocation success. 1 << compact_defer_shift, compactions are skipped up
  * to a limit of 1 << COMPACT_MAX_DEFER_SHIFT
  */
 void defer_compaction(struct zone *zone, int order)