linux-kernel - Re: [PATCH v2] parisc: use memblock_alloc() instead of custom get

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Date:   Thu, 21 Feb 2019 11:07:53 +0200
From:   Mike Rapoport <rppt@...ux.ibm.com>
To:     "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
        Helge Deller <deller@....de>
Cc:     Matthew Wilcox <willy@...radead.org>, linux-parisc@...r.kernel.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] parisc: use memblock_alloc() instead of custom
 get_memblock()

Any comments on this?

On Tue, Feb 12, 2019 at 05:16:12PM +0200, Mike Rapoport wrote:
> The get_memblock() function implements custom bottom-up memblock allocator.
> Setting 'memblock_bottom_up = true' before any memblock allocation is done
> allows replacing get_memblock() calls with memblock_alloc().
> 
> Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>
> ---
> v2: fix allocation alignment
> 
>  arch/parisc/mm/init.c | 52 +++++++++++++++++++--------------------------------
>  1 file changed, 19 insertions(+), 33 deletions(-)
> 
> diff --git a/arch/parisc/mm/init.c b/arch/parisc/mm/init.c
> index 059187a..d0b1662 100644
> --- a/arch/parisc/mm/init.c
> +++ b/arch/parisc/mm/init.c
> @@ -79,36 +79,6 @@ static struct resource sysram_resources[MAX_PHYSMEM_RANGES] __read_mostly;
>  physmem_range_t pmem_ranges[MAX_PHYSMEM_RANGES] __read_mostly;
>  int npmem_ranges __read_mostly;
>  
> -/*
> - * get_memblock() allocates pages via memblock.
> - * We can't use memblock_find_in_range(0, KERNEL_INITIAL_SIZE) here since it
> - * doesn't allocate from bottom to top which is needed because we only created
> - * the initial mapping up to KERNEL_INITIAL_SIZE in the assembly bootup code.
> - */
> -static void * __init get_memblock(unsigned long size)
> -{
> -	static phys_addr_t search_addr __initdata;
> -	phys_addr_t phys;
> -
> -	if (!search_addr)
> -		search_addr = PAGE_ALIGN(__pa((unsigned long) &_end));
> -	search_addr = ALIGN(search_addr, size);
> -	while (!memblock_is_region_memory(search_addr, size) ||
> -		memblock_is_region_reserved(search_addr, size)) {
> -		search_addr += size;
> -	}
> -	phys = search_addr;
> -
> -	if (phys)
> -		memblock_reserve(phys, size);
> -	else
> -		panic("get_memblock() failed.\n");
> -
> -	memset(__va(phys), 0, size);
> -
> -	return __va(phys);
> -}
> -
>  #ifdef CONFIG_64BIT
>  #define MAX_MEM         (~0UL)
>  #else /* !CONFIG_64BIT */
> @@ -321,6 +291,13 @@ static void __init setup_bootmem(void)
>  			max_pfn = start_pfn + npages;
>  	}
>  
> +	/*
> +	 * We can't use memblock top-down allocations because we only
> +	 * created the initial mapping up to KERNEL_INITIAL_SIZE in
> +	 * the assembly bootup code.
> +	 */
> +	memblock_set_bottom_up(true);
> +
>  	/* IOMMU is always used to access "high mem" on those boxes
>  	 * that can support enough mem that a PCI device couldn't
>  	 * directly DMA to any physical addresses.
> @@ -442,7 +419,10 @@ static void __init map_pages(unsigned long start_vaddr,
>  		 */
>  
>  		if (!pmd) {
> -			pmd = (pmd_t *) get_memblock(PAGE_SIZE << PMD_ORDER);
> +			pmd = memblock_alloc(PAGE_SIZE << PMD_ORDER,
> +					     PAGE_SIZE << PMD_ORDER);
> +			if (!pmd)
> +				panic("pmd allocation failed.\n");
>  			pmd = (pmd_t *) __pa(pmd);
>  		}
>  
> @@ -461,7 +441,10 @@ static void __init map_pages(unsigned long start_vaddr,
>  
>  			pg_table = (pte_t *)pmd_address(*pmd);
>  			if (!pg_table) {
> -				pg_table = (pte_t *) get_memblock(PAGE_SIZE);
> +				pg_table = memblock_alloc(PAGE_SIZE,
> +							  PAGE_SIZE);
> +				if (!pg_table)
> +					panic("page table allocation failed\n");
>  				pg_table = (pte_t *) __pa(pg_table);
>  			}
>  
> @@ -700,7 +683,10 @@ static void __init pagetable_init(void)
>  	}
>  #endif
>  
> -	empty_zero_page = get_memblock(PAGE_SIZE);
> +	empty_zero_page = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
> +	if (!empty_zero_page)
> +		panic("zero page allocation failed.\n");
> +
>  }
>  
>  static void __init gateway_init(void)
> -- 
> 2.7.4
> 

-- 
Sincerely yours,
Mike.