[PATCH v4 RESEND 1/3] mm/sparse: optimize sparse_index_alloc

[Gavin Shan <shangw@linux.vnet.ibm.com>]

With CONFIG_SPARSEMEM_EXTREME, the two level of memory section
descriptors are allocated from slab or bootmem. When allocating
from slab, let slab/bootmem allocator to clear the memory chunk.
We needn't clear that explicitly.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
---
 mm/sparse.c |   10 ++++------
 1 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/mm/sparse.c b/mm/sparse.c
index c7bb952..d882e88 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -65,14 +65,12 @@ static struct mem_section noinline __init_refok *sparse_index_alloc(int nid)
 
 	if (slab_is_available()) {
 		if (node_state(nid, N_HIGH_MEMORY))
-			section = kmalloc_node(array_size, GFP_KERNEL, nid);
+			section = kzalloc_node(array_size, GFP_KERNEL, nid);
 		else
-			section = kmalloc(array_size, GFP_KERNEL);
-	} else
+			section = kzalloc(array_size, GFP_KERNEL);
+	} else {
 		section = alloc_bootmem_node(NODE_DATA(nid), array_size);
-
-	if (section)
-		memset(section, 0, array_size);
+	}
 
 	return section;
 }
-- 
1.7.5.4

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