Subject: [PATCH v2 6/9] memblock: extract page freeing from free_reserved_area() into a helper

From: Mike Rapoport <[email-masked]>
Date: Mon, 23 Mar 2026 09:48:33 +0200

From: "Mike Rapoport (Microsoft)" <[email-masked]>

There are two functions that release pages to the buddy allocator late in
the boot: free_reserved_area() and memblock_free_late().

Currently they are using different underlying functionality,
free_reserved_area() runs each page being freed via free_reserved_page()
and memblock_free_late() uses memblock_free_pages() -> __free_pages_core(),
but in the end they both boil down to a loop that frees a range page by
page.

Extract the loop frees pages from free_reserved_area() into a helper and
use that helper in memblock_free_late().

Signed-off-by: Mike Rapoport (Microsoft) <[email-masked]>
---
 mm/memblock.c | 55 +++++++++++++++++++++++++++------------------------
 1 file changed, 29 insertions(+), 26 deletions(-)

diff --git a/mm/memblock.c b/mm/memblock.c
index eb086724802a..ccdf3d225626 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -893,26 +893,12 @@ int __init_memblock memblock_remove(phys_addr_t base, phys_addr_t size)
 	return memblock_remove_range(&memblock.memory, base, size);
 }
 
-unsigned long free_reserved_area(void *start, void *end, int poison, const char *s)
+static unsigned long __free_reserved_area(phys_addr_t start, phys_addr_t end,
+					  int poison)
 {
-	phys_addr_t start_pa, end_pa;
 	unsigned long pages = 0, pfn;
 
-	/*
-	 * end is the first address past the region and it may be beyond what
-	 * __pa() or __pa_symbol() can handle.
-	 * Use the address included in the range for the conversion and add
-	 * back 1 afterwards.
-	 */
-	if (__is_kernel((unsigned long)start)) {
-		start_pa = __pa_symbol(start);
-		end_pa = __pa_symbol(end - 1) + 1;
-	} else {
-		start_pa = __pa(start);
-		end_pa = __pa(end - 1) + 1;
-	}
-
-	for_each_valid_pfn(pfn, PFN_UP(start_pa), PFN_DOWN(end_pa)) {
+	for_each_valid_pfn(pfn, PFN_UP(start), PFN_DOWN(end)) {
 		struct page *page = pfn_to_page(pfn);
 		void *direct_map_addr;
 
@@ -934,7 +920,29 @@ unsigned long free_reserved_area(void *start, void *end, int poison, const char
 		free_reserved_page(page);
 		pages++;
 	}
+	return pages;
+}
+
+unsigned long free_reserved_area(void *start, void *end, int poison, const char *s)
+{
+	phys_addr_t start_pa, end_pa;
+	unsigned long pages;
+
+	/*
+	 * end is the first address past the region and it may be beyond what
+	 * __pa() or __pa_symbol() can handle.
+	 * Use the address included in the range for the conversion and add back
+	 * 1 afterwards.
+	 */
+	if (__is_kernel((unsigned long)start)) {
+		start_pa = __pa_symbol(start);
+		end_pa = __pa_symbol(end - 1) + 1;
+	} else {
+		start_pa = __pa(start);
+		end_pa = __pa(end - 1) + 1;
+	}
 
+	pages = __free_reserved_area(start_pa, end_pa, poison);
 	if (pages && s)
 		pr_info("Freeing %s memory: %ldK\n", s, K(pages));
 
@@ -1810,20 +1818,15 @@ void *__init __memblock_alloc_or_panic(phys_addr_t size, phys_addr_t align,
  */
 void __init memblock_free_late(phys_addr_t base, phys_addr_t size)
 {
-	phys_addr_t cursor, end;
+	phys_addr_t end = base + size - 1;
 
-	end = base + size - 1;
 	memblock_dbg("%s: [%pa-%pa] %pS\n",
 		     __func__, &base, &end, (void *)_RET_IP_);
-	kmemleak_free_part_phys(base, size);
-	cursor = PFN_UP(base);
-	end = PFN_DOWN(base + size);
 
-	for (; cursor < end; cursor++) {
-		memblock_free_pages(cursor, 0);
-		totalram_pages_inc();
-	}
+	kmemleak_free_part_phys(base, size);
+	__free_reserved_area(base, base + size, -1);
 }
+
 /*
  * Remaining API functions
  */
-- 
2.53.0