[PATCH V2] x86,NUMA:improve the execution efficiency of numa_meminfo_cover_memory()

[Liam Ni <zhiguangni01@gmail.com>]

The number of pages in memblock that doesn't have the node
assigned,which also means that these pages are not in numa_info.
So these pages can represent the number of lose pages.

Signed-off-by: Liam Ni <zhiguangni01@gmail.com>
---
 arch/x86/mm/numa.c | 25 ++++++-------------------
 include/linux/mm.h |  2 ++
 mm/mm_init.c       | 26 ++++++++++++++++++++++++++
 3 files changed, 34 insertions(+), 19 deletions(-)

diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
index 2aadb2019b4f..ffe3b771eac7 100644
--- a/arch/x86/mm/numa.c
+++ b/arch/x86/mm/numa.c
@@ -451,28 +451,15 @@ EXPORT_SYMBOL(__node_distance);
  * Sanity check to catch more bad NUMA configurations (they are amazingly
  * common).  Make sure the nodes cover all memory.
  */
-static bool __init numa_meminfo_cover_memory(const struct numa_meminfo *mi)
+static bool __init numa_meminfo_cover_memory(void)
 {
-	u64 numaram, e820ram;
-	int i;
-
-	numaram = 0;
-	for (i = 0; i < mi->nr_blks; i++) {
-		u64 s = mi->blk[i].start >> PAGE_SHIFT;
-		u64 e = mi->blk[i].end >> PAGE_SHIFT;
-		numaram += e - s;
-		numaram -= __absent_pages_in_range(mi->blk[i].nid, s, e);
-		if ((s64)numaram < 0)
-			numaram = 0;
-	}
+	u64 lo_pages;
 
-	e820ram = max_pfn - absent_pages_in_range(0, max_pfn);
+	lo_pages = without_node_pages_in_range(0, max_pfn);
 
 	/* We seem to lose 3 pages somewhere. Allow 1M of slack. */
-	if ((s64)(e820ram - numaram) >= (1 << (20 - PAGE_SHIFT))) {
-		printk(KERN_ERR "NUMA: nodes only cover %LuMB of your %LuMB e820 RAM. Not used.\n",
-		       (numaram << PAGE_SHIFT) >> 20,
-		       (e820ram << PAGE_SHIFT) >> 20);
+	if (lo_pages >= (1 << (20 - PAGE_SHIFT))) {
+		printk(KERN_ERR "NUMA: we lose more than 1M pages\n");
 		return false;
 	}
 	return true;
@@ -583,7 +570,7 @@ static int __init numa_register_memblks(struct numa_meminfo *mi)
 			return -EINVAL;
 		}
 	}
-	if (!numa_meminfo_cover_memory(mi))
+	if (!numa_meminfo_cover_memory())
 		return -EINVAL;
 
 	/* Finally register nodes. */
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0daef3f2f029..99b7b49f1378 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3043,6 +3043,8 @@ unsigned long __absent_pages_in_range(int nid, unsigned long start_pfn,
 						unsigned long end_pfn);
 extern unsigned long absent_pages_in_range(unsigned long start_pfn,
 						unsigned long end_pfn);
+extern unsigned long without_node_pages_in_range(unsigned long start_pfn,
+						unsigned long end_pfn);
 extern void get_pfn_range_for_nid(unsigned int nid,
 			unsigned long *start_pfn, unsigned long *end_pfn);
 
diff --git a/mm/mm_init.c b/mm/mm_init.c
index 3ddd18a89b66..1d5085a8f93b 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -1132,6 +1132,32 @@ static void __init adjust_zone_range_for_zone_movable(int nid,
 	}
 }
 
+/**
+ * @start_pfn: The start PFN to start searching for holes
+ * @end_pfn: The end PFN to stop searching for holes
+ *
+ * Return: Return the number of page frames without node assigned within a range.
+ */
+unsigned long __init without_node_pages_in_range(unsigned long start_pfn,
+						unsigned long end_pfn)
+{
+	struct memblock_type *type = &memblock.memory;
+	struct memblock_region *r;
+	unsigned long num_pages;
+	int i, nid;
+
+	for (i = 0; i < type->cnt; i++) {
+		r = &type->regions[i];
+		nid = memblock_get_region_node(r);
+
+		if (PFN_UP(r->base) >= PFN_DOWN(r->base + r->size))
+			continue;
+		if (nid == NUMA_NO_NODE)
+			num_pages += PFN_DOWN(r->base + r->size) - PFN_UP(r->base);
+	}
+	return num_pages;
+}
+
 /*
  * Return the number of holes in a range on a node. If nid is MAX_NUMNODES,
  * then all holes in the requested range will be accounted for.
-- 
2.25.1