On 07.06.22 11:38, Wupeng Ma wrote:
> From: Ma Wupeng <mawupeng1@xxxxxxxxxx>
>
> Initrd memory will be removed and then added in arm64_memblock_init() and this
> will cause it to lose all of its memblock flags. The lost of MEMBLOCK_MIRROR
> flag will lead to error log printed by find_zone_movable_pfns_for_nodes if
> the lower 4G range has some non-mirrored memory.
>
> In order to solve this problem, the lost MEMBLOCK_MIRROR flag will be
> reinstalled if the origin memblock has this flag.
>
> Signed-off-by: Ma Wupeng <mawupeng1@xxxxxxxxxx>
> ---
> arch/arm64/mm/init.c | 9 +++++++++
> include/linux/memblock.h | 1 +
> mm/memblock.c | 20 ++++++++++++++++++++
> 3 files changed, 30 insertions(+)
>
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 339ee84e5a61..11641f924d08 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -350,9 +350,18 @@ void __init arm64_memblock_init(void)
> "initrd not fully accessible via the linear mapping -- please check your bootloader ...\n")) {
> phys_initrd_size = 0;
> } else {
> + int flags, ret;
> +
> + ret = memblock_get_flags(base, &flags);
> + if (ret)
> + flags = 0;
> +
> memblock_remove(base, size); /* clear MEMBLOCK_ flags */
> memblock_add(base, size);
> memblock_reserve(base, size);
Can you explain why we're removing+re-adding here exactly? Is it just to
clear flags as the comment indicates?
If it's really just about clearing flags, I wonder if we rather want to
have an interface that does exactly that, and hides the way this is
actually implemented (obtain flags, remove, re-add ...), internally.
But most probably there is more magic in the code and clearing flags
isn't all it ends up doing.
--
Thanks,
David / dhildenb
