Re: [PATCH v2 2/3] mm: don't rely on system state to detect hot-plug operations

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Le 14/09/2020 à 19:15, David Hildenbrand a écrit :
  arch/ia64/mm/init.c  |  4 +--
  drivers/base/node.c  | 86 ++++++++++++++++++++++++++++----------------
  include/linux/node.h | 11 +++---
  mm/memory_hotplug.c  |  5 +--
  4 files changed, 68 insertions(+), 38 deletions(-)

diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c
index b5054b5e77c8..8e7b8c6c576e 100644
--- a/arch/ia64/mm/init.c
+++ b/arch/ia64/mm/init.c
@@ -538,7 +538,7 @@ virtual_memmap_init(u64 start, u64 end, void *arg)
  	if (map_start < map_end)
  		memmap_init_zone((unsigned long)(map_end - map_start),
  				 args->nid, args->zone, page_to_pfn(map_start),
-				 MEMPLUG_EARLY, NULL);
+				 MEMINIT_EARLY, NULL);

Patch #1.

Sure, this explains why I was able to build on ia64 but that's not the right place.

  	return 0;
  }
@@ -548,7 +548,7 @@ memmap_init (unsigned long size, int nid, unsigned long zone,
  {
  	if (!vmem_map) {
  		memmap_init_zone(size, nid, zone, start_pfn,
-				 MEMPLUG_EARLY, NULL);
+				 MEMINIT_EARLY, NULL);

I'll fix that too.

  	} else {
  		struct page *start;
  		struct memmap_init_callback_data args;
diff --git a/drivers/base/node.c b/drivers/base/node.c
index 508b80f6329b..01ee73c9d675 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -761,14 +761,36 @@ static int __ref get_nid_for_pfn(unsigned long pfn)
  	return pfn_to_nid(pfn);
  }
+static int do_register_memory_block_under_node(int nid,
+					       struct memory_block *mem_blk)
+{
+	int ret;
+
+	/*
+	 * If this memory block spans multiple nodes, we only indicate
+	 * the last processed node.
+	 */
+	mem_blk->nid = nid;
+
+	ret = sysfs_create_link_nowarn(&node_devices[nid]->dev.kobj,
+				       &mem_blk->dev.kobj,
+				       kobject_name(&mem_blk->dev.kobj));
+	if (ret)
+		return ret;
+
+	return sysfs_create_link_nowarn(&mem_blk->dev.kobj,
+				&node_devices[nid]->dev.kobj,
+				kobject_name(&node_devices[nid]->dev.kobj));
+}
+
  /* register memory section under specified node if it spans that node */
-static int register_mem_sect_under_node(struct memory_block *mem_blk,
-					 void *arg)
+static int register_mem_block_under_node_early(struct memory_block *mem_blk,
+					       void *arg)
  {
  	unsigned long memory_block_pfns = memory_block_size_bytes() / PAGE_SIZE;
  	unsigned long start_pfn = section_nr_to_pfn(mem_blk->start_section_nr);
  	unsigned long end_pfn = start_pfn + memory_block_pfns - 1;
-	int ret, nid = *(int *)arg;
+	int nid = *(int *)arg;
  	unsigned long pfn;
for (pfn = start_pfn; pfn <= end_pfn; pfn++) {
@@ -785,38 +807,34 @@ static int register_mem_sect_under_node(struct memory_block *mem_blk,
  		}
/*
-		 * We need to check if page belongs to nid only for the boot
-		 * case, during hotplug we know that all pages in the memory
-		 * block belong to the same node.
-		 */
-		if (system_state == SYSTEM_BOOTING) {
-			page_nid = get_nid_for_pfn(pfn);
-			if (page_nid < 0)
-				continue;
-			if (page_nid != nid)
-				continue;
-		}
-
-		/*
-		 * If this memory block spans multiple nodes, we only indicate
-		 * the last processed node.
+		 * We need to check if page belongs to nid only at the boot
+		 * case because node's ranges can be interleaved.
  		 */
-		mem_blk->nid = nid;
-
-		ret = sysfs_create_link_nowarn(&node_devices[nid]->dev.kobj,
-					&mem_blk->dev.kobj,
-					kobject_name(&mem_blk->dev.kobj));
-		if (ret)
-			return ret;
+		page_nid = get_nid_for_pfn(pfn);
+		if (page_nid < 0)
+			continue;
+		if (page_nid != nid)
+			continue;
- return sysfs_create_link_nowarn(&mem_blk->dev.kobj,
-				&node_devices[nid]->dev.kobj,
-				kobject_name(&node_devices[nid]->dev.kobj));
+		/* The memory block is registered to the first matching node */

That comment is misleading in that context.

A memory block is registered if there is at least a page that belongs to
the nid. It's perfectly fine to have a single memory block belong to
multiple NUMA nodes (when the split is within a memory block). I'd just
drop it.

I agree the comment is not accurate, I'll drop it.




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