[PATCH] mm/sparse: Optimize sparse_add_one_section()

[Baoquan He]

Reorder the allocation of usemap and memmap since usemap allocation
is much smaller and simpler. Otherwise hard work is done to make
memmap ready, then have to rollback just because of usemap allocation
failure.

Meanwhile update the error handler to cover usemap allocation failure
too.

Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>
---
 mm/sparse.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/mm/sparse.c b/mm/sparse.c
index a99e0b253927..0e842b924be6 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -699,20 +699,21 @@ int __meminit sparse_add_one_section(int nid, unsigned long start_pfn,
 	ret = sparse_index_init(section_nr, nid);
 	if (ret < 0 && ret != -EEXIST)
 		return ret;
-	ret = 0;
-	memmap = kmalloc_section_memmap(section_nr, nid, altmap);
-	if (!memmap)
-		return -ENOMEM;
+
 	usemap = __kmalloc_section_usemap();
-	if (!usemap) {
-		__kfree_section_memmap(memmap, altmap);
+	if (!usemap)
 		return -ENOMEM;
+	memmap = kmalloc_section_memmap(section_nr, nid, altmap);
+	if (!memmap) {
+		ret = -ENOMEM;
+		goto out2;
 	}
 
+	ret = 0;
 	ms = __pfn_to_section(start_pfn);
 	if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
 		ret = -EEXIST;
-		goto out;
+		goto out2;
 	}
 
 	/*
@@ -724,11 +725,11 @@ int __meminit sparse_add_one_section(int nid, unsigned long start_pfn,
 	section_mark_present(ms);
 	sparse_init_one_section(ms, section_nr, memmap, usemap);
 
+	return ret;
 out:
-	if (ret < 0) {
-		kfree(usemap);
-		__kfree_section_memmap(memmap, altmap);
-	}
+	__kfree_section_memmap(memmap, altmap);
+out2:
+	kfree(usemap);
 	return ret;
 }
 
-- 
2.17.2