+ mm-mm_initc-introduce-reset_memoryless_node_totalpages.patch added to mm-unstable branch

+ mm-mm_initc-introduce-reset_memoryless_node_totalpages.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/mm_init.c: introduce reset_memoryless_node_totalpages()
has been added to the -mm mm-unstable branch.  Its filename is
     mm-mm_initc-introduce-reset_memoryless_node_totalpages.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mm_initc-introduce-reset_memoryless_node_totalpages.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Haifeng Xu <haifeng.xu@shopee.com>
Subject: mm/mm_init.c: introduce reset_memoryless_node_totalpages()
Date: Fri, 26 May 2023 08:52:50 +0000

Currently, no matter whether a node actually has memory or not,
calculate_node_totalpages() is used to account number of pages in
zone/node.  However, for node without memory, these unnecessary
calculations can be skipped.  All the zone/node page counts can be set to
0 directly.  So introduce reset_memoryless_node_totalpages() to perform
this action.

Furthermore, calculate_node_totalpages() only gets called for the node
with memory.

Link: https://lkml.kernel.org/r/20230526085251.1977-1-haifeng.xu@shopee.com
Signed-off-by: Haifeng Xu <haifeng.xu@shopee.com>
Suggested-by: Mike Rapoport <rppt@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/mm_init.c |   31 ++++++++++++++++++++++---------
 1 file changed, 22 insertions(+), 9 deletions(-)

--- a/mm/mm_init.c~mm-mm_initc-introduce-reset_memoryless_node_totalpages
+++ a/mm/mm_init.c
@@ -1176,10 +1176,6 @@ static unsigned long __init zone_absent_
 	unsigned long zone_start_pfn, zone_end_pfn;
 	unsigned long nr_absent;
 
-	/* When hotadd a new node from cpu_up(), the node should be empty */
-	if (!node_start_pfn && !node_end_pfn)
-		return 0;
-
 	zone_start_pfn = clamp(node_start_pfn, zone_low, zone_high);
 	zone_end_pfn = clamp(node_end_pfn, zone_low, zone_high);
 
@@ -1229,9 +1225,6 @@ static unsigned long __init zone_spanned
 {
 	unsigned long zone_low = arch_zone_lowest_possible_pfn[zone_type];
 	unsigned long zone_high = arch_zone_highest_possible_pfn[zone_type];
-	/* When hotadd a new node from cpu_up(), the node should be empty */
-	if (!node_start_pfn && !node_end_pfn)
-		return 0;
 
 	/* Get the start and end of the zone */
 	*zone_start_pfn = clamp(node_start_pfn, zone_low, zone_high);
@@ -1252,6 +1245,24 @@ static unsigned long __init zone_spanned
 	return *zone_end_pfn - *zone_start_pfn;
 }
 
+static void __init reset_memoryless_node_totalpages(struct pglist_data *pgdat)
+{
+	struct zone *z;
+
+	for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++) {
+		z->zone_start_pfn = 0;
+		z->spanned_pages = 0;
+		z->present_pages = 0;
+#if defined(CONFIG_MEMORY_HOTPLUG)
+		z->present_early_pages = 0;
+#endif
+	}
+
+	pgdat->node_spanned_pages = 0;
+	pgdat->node_present_pages = 0;
+	pr_debug("On node %d totalpages: 0\n", pgdat->node_id);
+}
+
 static void __init calculate_node_totalpages(struct pglist_data *pgdat,
 						unsigned long node_start_pfn,
 						unsigned long node_end_pfn)
@@ -1704,11 +1715,13 @@ static void __init free_area_init_node(i
 		pr_info("Initmem setup node %d [mem %#018Lx-%#018Lx]\n", nid,
 			(u64)start_pfn << PAGE_SHIFT,
 			end_pfn ? ((u64)end_pfn << PAGE_SHIFT) - 1 : 0);
+
+		calculate_node_totalpages(pgdat, start_pfn, end_pfn);
 	} else {
 		pr_info("Initmem setup node %d as memoryless\n", nid);
-	}
 
-	calculate_node_totalpages(pgdat, start_pfn, end_pfn);
+		reset_memoryless_node_totalpages(pgdat);
+	}
 
 	alloc_node_mem_map(pgdat);
 	pgdat_set_deferred_range(pgdat);
_

Patches currently in -mm which might be from haifeng.xu@shopee.com are

memcg-oom-remove-unnecessary-check-in-mem_cgroup_oom_synchronize.patch
memcg-oom-remove-explicit-wakeup-in-mem_cgroup_oom_synchronize.patch
mm-oom-do-not-check-0-mask-in-out_of_memory.patch
mm-memcontrol-fix-typo-in-comment.patch
selftests-cgroup-fix-unexpected-failure-on-test_memcg_low.patch
mm-mm_initc-introduce-reset_memoryless_node_totalpages.patch
mm-mm_initc-do-not-calculate-zone_start_pfn-zone_end_pfn-in-zone_absent_pages_in_node.patch
fork-optimize-memcg_charge_kernel_stack-a-bit.patch