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Date:   Thu, 2 Apr 2020 15:07:13 -0700
From:   Matthew Wilcox <willy@infradead.org>
To:     Aslan Bakirov <aslan@fb.com>
Cc:     akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, kernel-team@fb.com, riel@surriel.com,
        guro@fb.com, mhocko@kernel.org, hannes@cmpxchg.org
Subject: Re: [PATCH v2] mm: cma: NUMA node interface
Message-ID: <20200402220713.GO21484@bombadil.infradead.org>
References: <20200402215810.1898270-1-aslan@fb.com>
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On Thu, Apr 02, 2020 at 02:58:10PM -0700, Aslan Bakirov wrote:
> I've noticed that there is no interfaces exposed by CMA which would let me
> to declare contigous memory on particular NUMA node.

Do you have a user for this functionality?

> +++ b/include/linux/cma.h
> @@ -24,10 +24,20 @@ extern phys_addr_t cma_get_base(const struct cma *cma);
>  extern unsigned long cma_get_size(const struct cma *cma);
>  extern const char *cma_get_name(const struct cma *cma);
>  
> -extern int __init cma_declare_contiguous(phys_addr_t base,
> +extern int __init cma_declare_contiguous_nid(phys_addr_t base,
>  			phys_addr_t size, phys_addr_t limit,
>  			phys_addr_t alignment, unsigned int order_per_bit,
> -			bool fixed, const char *name, struct cma **res_cma);
> +			bool fixed, const char *name, struct cma **res_cma,
> +			int nid);
> +static inline int __init cma_declare_contiguous(phys_addr_t base,
> +			phys_addr_t size, phys_addr_t limit,
> +			phys_addr_t alignment, unsigned int order_per_bit,
> +			bool fixed, const char *name, struct cma **res_cma)
> +			{
> +				return cma_declare_contiguous_nid(base, size,
> +						limit, alignment, order_per_bit,
> +						fixed, name, res_cma, NUMA_NO_NODE);
> +			}

... what even is this indentation?

> +phys_addr_t memblock_alloc_range_nid(phys_addr_t size,
> +					  phys_addr_t align, phys_addr_t start,
> +					  phys_addr_t end, int nid, bool exact_nid);

>80 columns.  checkpatch should warn you of nits like this.

>  		if (base < highmem_start && limit > highmem_start) {
> -			addr = memblock_phys_alloc_range(size, alignment,
> -							 highmem_start, limit);
> +			addr = memblock_alloc_range_nid(size, alignment,
> +							 highmem_start, limit, nid, false);

The deep indentation makes it hard to add new parameters.  I'd do it as:
			addr = memblock_alloc_range_nid(size, alignment,
					highmem_start, limit, nid, false);