[PATCH 6/8] memblock: make free_reserved_area() update memblock if ARCH_KEEP_MEMBLOCK=y

Mike Rapoport
2026-03-18T10:59:52Z

On architectures that keep memblock after boot, freeing of reserved memory
with free_reserved_area() is paired with an update of memblock arrays,
usually by a call to memblock_free().

Make free_reserved_area() directly update memblock.reserved when
ARCH_KEEP_MEMBLOCK is enabled.

Remove the now-redundant explicit memblock_free() call from
arm64::free_initmem() and the #ifdef CONFIG_ARCH_KEEP_MEMBLOCK block
from the generic free_initrd_mem().

Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
arch/arm64/mm/init.c | 3 ---
init/initramfs.c | 7 -------
mm/memblock.c | 6 ++++++
3 files changed, 6 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 96711b8578fd..07b17c708702 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -385,9 +385,6 @@ void free_initmem(void)
WARN_ON(!IS_ALIGNED((unsigned long)lm_init_begin, PAGE_SIZE));
WARN_ON(!IS_ALIGNED((unsigned long)lm_init_end, PAGE_SIZE));

- /* Delete __init region from memblock.reserved. */
- memblock_free(lm_init_begin, lm_init_end - lm_init_begin);
-
free_reserved_area(lm_init_begin, lm_init_end,
POISON_FREE_INITMEM, "unused kernel");
/*
diff --git a/init/initramfs.c b/init/initramfs.c
index 139baed06589..bca0922b2850 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -652,13 +652,6 @@ void __init reserve_initrd_mem(void)

void __weak __init free_initrd_mem(unsigned long start, unsigned long end)
{
-#ifdef CONFIG_ARCH_KEEP_MEMBLOCK
- unsigned long aligned_start = ALIGN_DOWN(start, PAGE_SIZE);
- unsigned long aligned_end = ALIGN(end, PAGE_SIZE);
-
- memblock_free((void *)aligned_start, aligned_end - aligned_start);
-#endif
-
free_reserved_area((void *)start, (void *)end, POISON_FREE_INITMEM,
"initrd");
}
diff --git a/mm/memblock.c b/mm/memblock.c
index 87bd200a8cc9..9f372a8e82f7 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -942,6 +942,12 @@ unsigned long free_reserved_area(void *start, void *end, int poison, const char
end_pa = __pa(end - 1) + 1;
}

+ if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) {
+ if (start_pa < end_pa)
+ memblock_remove_range(&memblock.reserved,
+ start_pa, end_pa - start_pa);
+ }
+
pages = __free_reserved_area(start_pa, end_pa, poison);
if (pages && s)
pr_info("Freeing %s memory: %ldK\n", s, K(pages));
--
2.51.0