linux-kernel - [PATCH 9/9] mm, sparse, page_ext: drop ugly N_HIGH

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Date:   Fri, 21 Jul 2017 16:39:15 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Mel Gorman <mgorman@...e.de>, Johannes Weiner <hannes@...xchg.org>,
        Vlastimil Babka <vbabka@...e.cz>, <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Michal Hocko <mhocko@...e.com>, Joonsoo Kim <js1304@...il.com>,
        Shaohua Li <shaohua.li@...el.com>
Subject: [PATCH 9/9] mm, sparse, page_ext: drop ugly N_HIGH_MEMORY branches for allocations

From: Michal Hocko <mhocko@...e.com>

f52407ce2dea ("memory hotplug: alloc page from other node in memory
online") has introduced N_HIGH_MEMORY checks to only use NUMA aware
allocations when there is some memory present because the respective
node might not have any memory yet at the time and so it could fail
or even OOM. Things have changed since then though. Zonelists are
now always initialized before we do any allocations even for hotplug
(see 959ecc48fc75 ("mm/memory_hotplug.c: fix building of node hotplug
zonelist")). Therefore these checks are not really needed. In fact
caller of the allocator should never care about whether the node is
populated because that might change at any time.

Cc: Shaohua Li <shaohua.li@...el.com>
Cc: Joonsoo Kim <js1304@...il.com>
Acked-by: Vlastimil Babka <vbabka@...e.cz>
Signed-off-by: Michal Hocko <mhocko@...e.com>
---
 mm/page_ext.c       |  5 +----
 mm/sparse-vmemmap.c | 11 +++--------
 mm/sparse.c         | 10 +++-------
 3 files changed, 7 insertions(+), 19 deletions(-)

diff --git a/mm/page_ext.c b/mm/page_ext.c
index 88ccc044b09a..714ce79256c5 100644
--- a/mm/page_ext.c
+++ b/mm/page_ext.c
@@ -222,10 +222,7 @@ static void *__meminit alloc_page_ext(size_t size, int nid)
 		return addr;
 	}
 
-	if (node_state(nid, N_HIGH_MEMORY))
-		addr = vzalloc_node(size, nid);
-	else
-		addr = vzalloc(size);
+	addr = vzalloc_node(size, nid);
 
 	return addr;
 }
diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index c50b1a14d55e..d1a39b8051e0 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -54,14 +54,9 @@ void * __meminit vmemmap_alloc_block(unsigned long size, int node)
 	if (slab_is_available()) {
 		struct page *page;
 
-		if (node_state(node, N_HIGH_MEMORY))
-			page = alloc_pages_node(
-				node, GFP_KERNEL | __GFP_ZERO | __GFP_RETRY_MAYFAIL,
-				get_order(size));
-		else
-			page = alloc_pages(
-				GFP_KERNEL | __GFP_ZERO | __GFP_RETRY_MAYFAIL,
-				get_order(size));
+		page = alloc_pages_node(node,
+			GFP_KERNEL | __GFP_ZERO | __GFP_RETRY_MAYFAIL,
+			get_order(size));
 		if (page)
 			return page_address(page);
 		return NULL;
diff --git a/mm/sparse.c b/mm/sparse.c
index 7b4be3fd5cac..a9783acf2bb9 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -65,14 +65,10 @@ static noinline struct mem_section __ref *sparse_index_alloc(int nid)
 	unsigned long array_size = SECTIONS_PER_ROOT *
 				   sizeof(struct mem_section);
 
-	if (slab_is_available()) {
-		if (node_state(nid, N_HIGH_MEMORY))
-			section = kzalloc_node(array_size, GFP_KERNEL, nid);
-		else
-			section = kzalloc(array_size, GFP_KERNEL);
-	} else {
+	if (slab_is_available())
+		section = kzalloc_node(array_size, GFP_KERNEL, nid);
+	else
 		section = memblock_virt_alloc_node(array_size, nid);
-	}
 
 	return section;
 }
-- 
2.11.0