On 04/09/20 at 07:27pm, Mike Rapoport wrote:

On Tue, Mar 31, 2020 at 04:21:38PM +0200, Michal Hocko wrote:

quoted

On Tue 31-03-20 22:03:32, Baoquan He wrote:

quoted

Hi Michal,

On 03/31/20 at 10:55am, Michal Hocko wrote:

quoted

On Tue 31-03-20 11:14:23, Mike Rapoport wrote:

quoted

Maybe I mis-read the code, but I don't see how this could happen. In the
HAVE_MEMBLOCK_NODE_MAP=y case, free_area_init_node() calls
calculate_node_totalpages() that ensures that node->node_zones are entirely
within the node because this is checked in zone_spanned_pages_in_node().

zone_spanned_pages_in_node does chech the zone boundaries are within the
node boundaries. But that doesn't really tell anything about other
potential zones interleaving with the physical memory range.
zone->spanned_pages simply gives the physical range for the zone
including holes. Interleaving nodes are essentially a hole
(__absent_pages_in_range is going to skip those).

That means that when free_area_init_core simply goes over the whole
physical zone range including holes and that is why we need to check
both for physical and logical holes (aka other nodes).

The life would be so much easier if the whole thing would simply iterate
over memblocks...

The memblock iterating sounds a great idea. I tried with putting the
memblock iterating in the upper layer, memmap_init(), which is used for
boot mem only anyway. Do you think it's doable and OK? It yes, I can
work out a formal patch to make this simpler as you said. The draft code
is as below. Like this it uses the existing code and involves little change.

Doing this would be a step in the right direction! I haven't checked the
code very closely though. The below sounds way too simple to be truth I
am afraid. First for_each_mem_pfn_range is available only for
CONFIG_HAVE_MEMBLOCK_NODE_MAP (which is one of the reasons why I keep
saying that I really hate that being conditional). Also I haven't really
checked the deferred initialization path - I have a very vague
recollection that it has been converted to the memblock api but I have
happilly dropped all that memory.

The Baoquan's patch almost did it, at least for simple case of qemu with 2
nodes. It's only missing the adjustment to the size passed to
memmap_init_zone() as it may change because of clamping.

Right, the size need be adjusted after start and end clamping.

I've drafted something that removes HAVE_MEMBLOCK_NODE_MAP and added this
patch there [1]. For several memory configurations I could emulate with
qemu it worked.
I'm going to wait a bit to see of kbuild is happy and then I'll send the
patches.

Baoquan, I took liberty to add your SoB, hope you don't mind.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/rppt/linux.git/log/?h=memblock/all-have-node-map 

Of course not. Thanks for doing this, and look forward to seeing your
formal patchset posting when it's ready.

quoted

quoted

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 138a56c0f48f..558d421f294b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c

@@ -6007,14 +6007,6 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
 		 * function.  They do not exist on hotplugged memory.
 		 */
 		if (context == MEMMAP_EARLY) {
-			if (!early_pfn_valid(pfn)) {
-				pfn = next_pfn(pfn);
-				continue;
-			}
-			if (!early_pfn_in_nid(pfn, nid)) {
-				pfn++;
-				continue;
-			}
 			if (overlap_memmap_init(zone, &pfn))
 				continue;
 			if (defer_init(nid, pfn, end_pfn))

@@ -6130,9 +6122,17 @@ static void __meminit zone_init_free_lists(struct zone *zone)
 }
 
 void __meminit __weak memmap_init(unsigned long size, int nid,
-				  unsigned long zone, unsigned long start_pfn)
+				  unsigned long zone, unsigned long range_start_pfn)
 {
-	memmap_init_zone(size, nid, zone, start_pfn, MEMMAP_EARLY, NULL);
+	unsigned long start_pfn, end_pfn;
+	unsigned long range_end_pfn = range_start_pfn + size;
+	int i;
+	for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) {
+		start_pfn = clamp(start_pfn, range_start_pfn, range_end_pfn);
+		end_pfn = clamp(end_pfn, range_start_pfn, range_end_pfn);
+		if (end_pfn > start_pfn)
+			memmap_init_zone(size, nid, zone, start_pfn, MEMMAP_EARLY, NULL);
+	}
 }
 
 static int zone_batchsize(struct zone *zone)

-- 
Michal Hocko
SUSE Labs

-- 
Sincerely yours,
Mike.