diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 51692054937823..2acdd046df2d5d 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -265,21 +265,6 @@ void __next_mem_pfn_range(int *idx, int nid, unsigned long *out_start_pfn,
 	for_each_mem_range_rev(i, &memblock.memory, &memblock.reserved,	\
 			       nid, flags, p_start, p_end, p_nid)
 
-/**
- * for_each_resv_unavail_range - iterate through reserved and unavailable memory
- * @i: u64 used as loop variable
- * @p_start: ptr to phys_addr_t for start address of the range, can be %NULL
- * @p_end: ptr to phys_addr_t for end address of the range, can be %NULL
- *
- * Walks over unavailable but reserved (reserved && !memory) areas of memblock.
- * Available as soon as memblock is initialized.
- * Note: because this memory does not belong to any physical node, flags and
- * nid arguments do not make sense and thus not exported as arguments.
- */
-#define for_each_resv_unavail_range(i, p_start, p_end)			\
-	for_each_mem_range(i, &memblock.reserved, &memblock.memory,	\
-			   NUMA_NO_NODE, MEMBLOCK_NONE, p_start, p_end, NULL)
-
 static inline void memblock_set_region_flags(struct memblock_region *r,
 					     enum memblock_flags flags)
 {
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c26d3152f9ba96..6d863c5afa086b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6515,29 +6515,42 @@ void __init free_area_init_node(int nid, unsigned long *zones_size,
  * struct pages which are reserved in memblock allocator and their fields
  * may be accessed (for example page_to_pfn() on some configuration accesses
  * flags). We must explicitly zero those struct pages.
+ *
+ * This function also addresses a similar issue where struct pages are left
+ * uninitialized because the physical address range is not covered by
+ * memblock.memory or memblock.reserved. That could happen when memblock
+ * layout is manually configured via memmap=.
  */
 void __init zero_resv_unavail(void)
 {
 	phys_addr_t start, end;
 	unsigned long pfn;
 	u64 i, pgcnt;
+	phys_addr_t next = 0;
 
 	/*
-	 * Loop through ranges that are reserved, but do not have reported
-	 * physical memory backing.
+	 * Loop through unavailable ranges not covered by memblock.memory.
 	 */
 	pgcnt = 0;
-	for_each_resv_unavail_range(i, &start, &end) {
-		for (pfn = PFN_DOWN(start); pfn < PFN_UP(end); pfn++) {
-			if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages))) {
-				pfn = ALIGN_DOWN(pfn, pageblock_nr_pages)
-					+ pageblock_nr_pages - 1;
-				continue;
+	for_each_mem_range(i, &memblock.memory, NULL,
+			NUMA_NO_NODE, MEMBLOCK_NONE, &start, &end, NULL) {
+		if (next < start) {
+			for (pfn = PFN_DOWN(next); pfn < PFN_UP(start); pfn++) {
+				if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages)))
+					continue;
+				mm_zero_struct_page(pfn_to_page(pfn));
+				pgcnt++;
 			}
-			mm_zero_struct_page(pfn_to_page(pfn));
-			pgcnt++;
 		}
+		next = end;
 	}
+	for (pfn = PFN_DOWN(next); pfn < max_pfn; pfn++) {
+		if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages)))
+			continue;
+		mm_zero_struct_page(pfn_to_page(pfn));
+		pgcnt++;
+	}
+
 
 	/*
 	 * Struct pages that do not have backing memory. This could be because
@@ -6547,7 +6560,8 @@ void __init zero_resv_unavail(void)
 	 * this code can be removed.
 	 */
 	if (pgcnt)
-		pr_info("Reserved but unavailable: %lld pages", pgcnt);
+		pr_info("Zeroed struct page in unavailable ranges: %lld pages", pgcnt);
+
 }
 #endif /* CONFIG_HAVE_MEMBLOCK && !CONFIG_FLAT_NODE_MEM_MAP */