If CONFIG_ARCH_KEEP_MEMBLOCK is enabled, the memory information in
memblock will be retained. We release the __init memory here, and
we should also delete the corresponding region in memblock.reserved.

Signed-off-by: Rong Qianfeng <rongqianfeng@vivo.com>
---
 arch/arm64/mm/init.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index bfb10969cbf0..99cfa217e905 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -402,6 +402,13 @@ void __init mem_init(void)
 
 void free_initmem(void)
 {
+	if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) {
+		unsigned long aligned_begin = ALIGN_DOWN((u64)__init_begin, PAGE_SIZE);
+		unsigned long aligned_end = ALIGN((u64)__init_end, PAGE_SIZE);
+
+		memblock_free((void *)aligned_begin, aligned_end - aligned_begin);
+	}
+
 	free_reserved_area(lm_alias(__init_begin),
 			   lm_alias(__init_end),
 			   POISON_FREE_INITMEM, "unused kernel");
-- 
2.39.0

Hi Rong,

On Fri, 30 Aug 2024 at 10:00, Rong Qianfeng <rongqianfeng@vivo.com> wrote:
>
> If CONFIG_ARCH_KEEP_MEMBLOCK is enabled, the memory information in
> memblock will be retained. We release the __init memory here, and
> we should also delete the corresponding region in memblock.reserved.
>
> Signed-off-by: Rong Qianfeng <rongqianfeng@vivo.com>
> ---
>  arch/arm64/mm/init.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index bfb10969cbf0..99cfa217e905 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -402,6 +402,13 @@ void __init mem_init(void)
>
>  void free_initmem(void)
>  {
> +       if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) {

This is always true on arm64

> +               unsigned long aligned_begin = ALIGN_DOWN((u64)__init_begin, PAGE_SIZE);
> +               unsigned long aligned_end = ALIGN((u64)__init_end, PAGE_SIZE);
> +
> +               memblock_free((void *)aligned_begin, aligned_end - aligned_begin);
> +       }
> +

What does this achieve? The memory is already being reused by the page
allocator (due to free_reserved_area()), and the memblock allocator is
no longer usable at this point anyway.

>         free_reserved_area(lm_alias(__init_begin),
>                            lm_alias(__init_end),
>                            POISON_FREE_INITMEM, "unused kernel");

在 2024/8/30 16:14, Ard Biesheuvel 写道:
> Hi Rong,
>
> On Fri, 30 Aug 2024 at 10:00, Rong Qianfeng <rongqianfeng@vivo.com> wrote:
>> If CONFIG_ARCH_KEEP_MEMBLOCK is enabled, the memory information in
>> memblock will be retained. We release the __init memory here, and
>> we should also delete the corresponding region in memblock.reserved.
>>
>> Signed-off-by: Rong Qianfeng <rongqianfeng@vivo.com>
>> ---
>>   arch/arm64/mm/init.c | 7 +++++++
>>   1 file changed, 7 insertions(+)
>>
>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
>> index bfb10969cbf0..99cfa217e905 100644
>> --- a/arch/arm64/mm/init.c
>> +++ b/arch/arm64/mm/init.c
>> @@ -402,6 +402,13 @@ void __init mem_init(void)
>>
>>   void free_initmem(void)
>>   {
>> +       if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) {
> This is always true on arm64
>
>> +               unsigned long aligned_begin = ALIGN_DOWN((u64)__init_begin, PAGE_SIZE);
>> +               unsigned long aligned_end = ALIGN((u64)__init_end, PAGE_SIZE);
>> +
>> +               memblock_free((void *)aligned_begin, aligned_end - aligned_begin);
>> +       }
>> +
> What does this achieve? The memory is already being reused by the page
> allocator (due to free_reserved_area()), and the memblock allocator is
> no longer usable at this point anyway.
If not,  incorrect information will be visible in
/sys/kernel/debug/memblock/reserved.

Best Regards,
Qianfeng
>
>>          free_reserved_area(lm_alias(__init_begin),
>>                             lm_alias(__init_end),
>>                             POISON_FREE_INITMEM, "unused kernel");