Re: [PATCH 5/5] arch: simplify several early memory allocations

[Christophe LEROY]

Le 25/11/2018 Ã 22:44, Mike Rapoport a ÃcritÂ:
> There are several early memory allocations in arch/ code that use
> memblock_phys_alloc() to allocate memory, convert the returned physical
> address to the virtual address and then set the allocated memory to zero.
>
> Exactly the same behaviour can be achieved simply by calling
> memblock_alloc(): it allocates the memory in the same way as
> memblock_phys_alloc(), then it performs the phys_to_virt() conversion and
> clears the allocated memory.
>
> Replace the longer sequence with a simpler call to memblock_alloc().
>
> Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
> ---
>   arch/arm/mm/mmu.c                     |  4 +---
>   arch/c6x/mm/dma-coherent.c            |  9 ++-------
>   arch/nds32/mm/init.c                  | 12 ++++--------
>   arch/powerpc/kernel/setup-common.c    |  4 ++--
>   arch/powerpc/mm/pgtable_32.c          |  4 +---
>   arch/powerpc/mm/ppc_mmu_32.c          |  3 +--
>   arch/powerpc/platforms/powernv/opal.c |  3 +--
>   arch/sparc/kernel/prom_64.c           |  7 ++-----
>   arch/sparc/mm/init_64.c               |  9 +++------
>   arch/unicore32/mm/mmu.c               |  4 +---
>   10 files changed, 18 insertions(+), 41 deletions(-)
[...]

> diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
> index bda3c6f..9931e68 100644
> --- a/arch/powerpc/mm/pgtable_32.c
> +++ b/arch/powerpc/mm/pgtable_32.c
> @@ -50,9 +50,7 @@ __ref pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
>   	if (slab_is_available()) {
>   		pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
>   	} else {
> -		pte = __va(memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE));
> -		if (pte)
> -			clear_page(pte);
> +		pte = memblock_alloc(PAGE_SIZE, PAGE_SIZE);

memblock_alloc() uses memset to zeroize the block.

clear_page() is more performant than memset().


Christophe

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