linux-kernel - Re: [PATCH v3 06/12] mm: track active portions of a section at boot

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Date:   Fri, 20 Jan 2017 09:56:10 -0800
From:   Dan Williams <dan.j.williams@...el.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Michal Hocko <mhocko@...e.com>,
        linux-nvdimm <linux-nvdimm@...1.01.org>,
        Logan Gunthorpe <logang@...tatee.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Stephen Bates <stephen.bates@...rosemi.com>,
        Linux MM <linux-mm@...ck.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Vlastimil Babka <vbabka@...e.cz>
Subject: Re: [PATCH v3 06/12] mm: track active portions of a section at boot

On Thu, Jan 19, 2017 at 4:05 PM, Andrew Morton
<akpm@...ux-foundation.org> wrote:
> On Thu, 19 Jan 2017 14:07:13 -0800 Dan Williams <dan.j.williams@...el.com> wrote:
>
>> Prepare for hot{plug,remove} of sub-ranges of a section by tracking a
>> section active bitmask, each bit representing 2MB (SECTION_SIZE (128M) /
>> map_active bitmask length (64)).
>>
>> --- a/include/linux/mmzone.h
>> +++ b/include/linux/mmzone.h
>> @@ -1083,6 +1083,8 @@ struct mem_section_usage {
>>       unsigned long pageblock_flags[0];
>>  };
>>
>> +void section_active_init(unsigned long pfn, unsigned long nr_pages);
>> +
>>  struct page;
>>  struct page_ext;
>>  struct mem_section {
>> @@ -1224,6 +1226,7 @@ void sparse_init(void);
>>  #else
>>  #define sparse_init()        do {} while (0)
>>  #define sparse_index_init(_sec, _nid)  do {} while (0)
>> +#define section_active_init(_pfn, _nr_pages) do {} while (0)
>
> Using a #define for this is crappy.  A static inline does typechecking
> and can suppress unused-var warnings in callers.
>
>>  #endif /* CONFIG_SPARSEMEM */
>>
>>  /*
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index 68ccf5bcdbb2..9a3ab6c245a8 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -6352,10 +6352,12 @@ void __init free_area_init_nodes(unsigned long *max_zone_pfn)
>>
>>       /* Print out the early node map */
>>       pr_info("Early memory node ranges\n");
>> -     for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid)
>> +     for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) {
>>               pr_info("  node %3d: [mem %#018Lx-%#018Lx]\n", nid,
>>                       (u64)start_pfn << PAGE_SHIFT,
>>                       ((u64)end_pfn << PAGE_SHIFT) - 1);
>> +             section_active_init(start_pfn, end_pfn - start_pfn);
>
> section_active_init() can be __init, methinks.  We don't want to carry
> the extra .text after boot.
>
> --- a/include/linux/mmzone.h~mm-track-active-portions-of-a-section-at-boot-fix
> +++ a/include/linux/mmzone.h
> @@ -1083,7 +1083,7 @@ struct mem_section_usage {
>         unsigned long pageblock_flags[0];
>  };
>
> -void section_active_init(unsigned long pfn, unsigned long nr_pages);
> +void __init section_active_init(unsigned long pfn, unsigned long nr_pages);
>
>  struct page;
>  struct page_ext;
> @@ -1226,6 +1226,10 @@ void sparse_init(void);
>  #else
>  #define sparse_init()  do {} while (0)
>  #define sparse_index_init(_sec, _nid)  do {} while (0)
> +static inline void section_active_init(unsigned long pfn,
> +                                      unsigned long nr_pages)
> +{
> +}
>  #define section_active_init(_pfn, _nr_pages) do {} while (0)
>  #endif /* CONFIG_SPARSEMEM */
>
> --- a/mm/sparse.c~mm-track-active-portions-of-a-section-at-boot-fix
> +++ a/mm/sparse.c
> @@ -168,13 +168,13 @@ void __meminit mminit_validate_memmodel_
>         }
>  }
>
> -static int section_active_index(phys_addr_t phys)
> +static int __init section_active_index(phys_addr_t phys)
>  {
>         return (phys & ~(PA_SECTION_MASK)) / SECTION_ACTIVE_SIZE;
>  }
>
> -static unsigned long section_active_mask(unsigned long pfn,
> -               unsigned long nr_pages)
> +static unsigned long __init section_active_mask(unsigned long pfn,
> +                                               unsigned long nr_pages)
>  {
>         int idx_start, idx_size;
>         phys_addr_t start, size;
> @@ -195,7 +195,7 @@ static unsigned long section_active_mask
>         return ((1UL << idx_size) - 1) << idx_start;
>  }
>
> -void section_active_init(unsigned long pfn, unsigned long nr_pages)
> +void __init section_active_init(unsigned long pfn, unsigned long nr_pages)
>  {
>         int end_sec = pfn_to_section_nr(pfn + nr_pages - 1);
>         int i, start_sec = pfn_to_section_nr(pfn);
> _
>

Yes, looks good to me.