On 3/15/23 12:31, Kirill A. Shutemov wrote:
> MAX_ORDER is not inclusive: the maximum allocation order buddy allocator
> can deliver is MAX_ORDER-1.
>
> Fix MAX_ORDER usage in linux_main().
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
> Cc: Richard Weinberger <richard@xxxxxx>
> Cc: Anton Ivanov <anton.ivanov@xxxxxxxxxxxxxxxxxx>
> Cc: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
> ---
> arch/um/kernel/um_arch.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
> index 8dcda617b8bf..5e5a9c8e0e5d 100644
> --- a/arch/um/kernel/um_arch.c
> +++ b/arch/um/kernel/um_arch.c
> @@ -368,10 +368,10 @@ int __init linux_main(int argc, char **argv)
> max_physmem = TASK_SIZE - uml_physmem - iomem_size - MIN_VMALLOC;
>
> /*
> - * Zones have to begin on a 1 << MAX_ORDER page boundary,
> + * Zones have to begin on a 1 << MAX_ORDER-1 page boundary,
> * so this makes sure that's true for highmem
> */
> - max_physmem &= ~((1 << (PAGE_SHIFT + MAX_ORDER)) - 1);
> + max_physmem &= ~((1 << (PAGE_SHIFT + MAX_ORDER - 1)) - 1);
> if (physmem_size + iomem_size > max_physmem) {
> highmem = physmem_size + iomem_size - max_physmem;
> physmem_size -= highmem;
