[PATCH V3] [PATCH V3] NUMA:Improve the efficiency of calculating pages loss

[Liam Ni]

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.

V2:https://lore.kernel.org/all/20230619075315.49114-1-zhiguangni01@xxxxxxxxx/
V1:https://lore.kernel.org/all/20230615142016.419570-1-zhiguangni01@xxxxxxxxx/

Signed-off-by: Liam Ni <zhiguangni01@xxxxxxxxx>
---
 arch/loongarch/kernel/numa.c | 23 ++++++++---------------
 arch/x86/mm/numa.c           | 26 +++++++-------------------
 include/linux/mm.h           |  1 +
 mm/mm_init.c                 | 20 ++++++++++++++++++++
 4 files changed, 36 insertions(+), 34 deletions(-)

diff --git a/arch/loongarch/kernel/numa.c b/arch/loongarch/kernel/numa.c
index 708665895b47..0239891e4d19 100644
--- a/arch/loongarch/kernel/numa.c
+++ b/arch/loongarch/kernel/numa.c
@@ -262,25 +262,18 @@ static void __init node_mem_init(unsigned int node)
  * 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 memblock_validate_numa_coverage(const u64 limit)
 {
-	int i;
-	u64 numaram, biosram;
+	u64 lo_pg;
 
-	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;
+	lo_pg = max_pfn - calculate_without_node_pages_in_range();
 
-		numaram += e - s;
-		numaram -= __absent_pages_in_range(mi->blk[i].nid, s, e);
-		if ((s64)numaram < 0)
-			numaram = 0;
+	/* We seem to lose 3 pages somewhere. Allow 1M of slack. */
+	if (lo_pg >= limit) {
+		pr_err("NUMA: We lost 1m size page.\n");
+		return false;
 	}
-	max_pfn = max_low_pfn;
-	biosram = max_pfn - absent_pages_in_range(0, max_pfn);
 
-	BUG_ON((s64)(biosram - numaram) >= (1 << (20 - PAGE_SHIFT)));
 	return true;
 }
 
@@ -428,7 +421,7 @@ int __init init_numa_memory(void)
 		return -EINVAL;
 
 	init_node_memblock();
-	if (numa_meminfo_cover_memory(&numa_meminfo) == false)
+	if (memblock_validate_numa_coverage(SZ_1M) == false)
 		return -EINVAL;
 
 	for_each_node_mask(node, node_possible_map) {
diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
index 2aadb2019b4f..14feec144675 100644
--- a/arch/x86/mm/numa.c
+++ b/arch/x86/mm/numa.c
@@ -451,30 +451,18 @@ 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 memblock_validate_numa_coverage(const u64 limit)
 {
-	u64 numaram, e820ram;
-	int i;
+	u64 lo_pg;
 
-	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;
-	}
-
-	e820ram = max_pfn - absent_pages_in_range(0, max_pfn);
+	lo_pg = max_pfn - calculate_without_node_pages_in_range();
 
 	/* 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_pg >= limit) {
+		pr_err("NUMA: We lost 1m size page.\n");
 		return false;
 	}
+
 	return true;
 }
 
@@ -583,7 +571,7 @@ static int __init numa_register_memblks(struct numa_meminfo *mi)
 			return -EINVAL;
 		}
 	}
-	if (!numa_meminfo_cover_memory(mi))
+	if (!memblock_validate_numa_coverage(SZ_1M))
 		return -EINVAL;
 
 	/* Finally register nodes. */
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0daef3f2f029..b32457ad1ae3 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3043,6 +3043,7 @@ 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 calculate_without_node_pages_in_range(void);
 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..13a4883787e3 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -1132,6 +1132,26 @@ 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 calculate_without_node_pages_in_range(void)
+{
+	unsigned long num_pages;
+	unsigned long start_pfn, end_pfn;
+	int nid, i;
+
+	for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) {
+		if (nid == NUMA_NO_NODE)
+			num_pages += end_pfn - start_pfn;
+	}
+
+	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