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From:   Dong Aisheng <aisheng.dong@nxp.com>
To:     linux-mm@kvack.org
Cc:     linux-kernel@vger.kernel.org, dongas86@gmail.com,
        Dong Aisheng <aisheng.dong@nxp.com>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH 3/5] mm/sparse: move mem_sections allocation out of memory_present()
Date:   Mon, 17 May 2021 19:20:42 +0800
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The only path to call memory_present() is from memblocks_present().
The struct mem_section **mem_section only needs to be initialized once,
so no need put the initialization/allocation code in memory_present()
which will be called multiple times for each section.

After moving, the 'unlikely' condition statement becomes to be
meaningless as it's only initialized one time, so dropped as well.

Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
---
 mm/sparse.c | 23 ++++++++++-------------
 1 file changed, 10 insertions(+), 13 deletions(-)

diff --git a/mm/sparse.c b/mm/sparse.c
index 98bfacc763da..df4418c12f04 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -254,19 +254,6 @@ static void __init memory_present(int nid, unsigned long start, unsigned long en
 {
 	unsigned long pfn;
 
-#ifdef CONFIG_SPARSEMEM_EXTREME
-	if (unlikely(!mem_section)) {
-		unsigned long size, align;
-
-		size = sizeof(struct mem_section *) * NR_SECTION_ROOTS;
-		align = 1 << (INTERNODE_CACHE_SHIFT);
-		mem_section = memblock_alloc(size, align);
-		if (!mem_section)
-			panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
-			      __func__, size, align);
-	}
-#endif
-
 	start &= PAGE_SECTION_MASK;
 	mminit_validate_memmodel_limits(&start, &end);
 	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
@@ -292,9 +279,19 @@ static void __init memory_present(int nid, unsigned long start, unsigned long en
  */
 static void __init memblocks_present(void)
 {
+	unsigned long __maybe_unused size, align;
 	unsigned long start, end;
 	int i, nid;
 
+#ifdef CONFIG_SPARSEMEM_EXTREME
+	size = sizeof(struct mem_section *) * NR_SECTION_ROOTS;
+	align = 1 << (INTERNODE_CACHE_SHIFT);
+	mem_section = memblock_alloc(size, align);
+	if (!mem_section)
+		panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
+		      __func__, size, align);
+#endif
+
 	for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, &nid)
 		memory_present(nid, start, end);
 }
-- 
2.25.1