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From: Joao Martins <joao.m.martins@oracle.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Linux MM <linux-mm@kvack.org>,
	Vishal Verma <vishal.l.verma@intel.com>,
	Dave Jiang <dave.jiang@intel.com>,
	Naoya Horiguchi <naoya.horiguchi@nec.com>,
	Matthew Wilcox <willy@infradead.org>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	John Hubbard <jhubbard@nvidia.com>,
	Jane Chu <jane.chu@oracle.com>,
	Muchun Song <songmuchun@bytedance.com>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Linux NVDIMM <nvdimm@lists.linux.dev>,
	Linux Doc Mailing List <linux-doc@vger.kernel.org>
Subject: Re: [PATCH v3 08/14] mm/sparse-vmemmap: populate compound pagemaps
Date: Wed, 28 Jul 2021 19:54:00 +0100	[thread overview]
Message-ID: <d7f1e0b9-bf57-b30e-84d5-cd0e5cdadaaf@oracle.com> (raw)
In-Reply-To: <CAPcyv4jR9atodmLqk4O+RdbM9DJDvoQvAZqH03UAgAKB71Fcdg@mail.gmail.com>



On 7/28/21 7:03 PM, Dan Williams wrote:
> On Wed, Jul 28, 2021 at 8:36 AM Joao Martins <joao.m.martins@oracle.com> wrote:
> [..]
>> +/*
>> + * For compound pages bigger than section size (e.g. x86 1G compound
>> + * pages with 2M subsection size) fill the rest of sections as tail
>> + * pages.
>> + *
>> + * Note that memremap_pages() resets @nr_range value and will increment
>> + * it after each range successful onlining. Thus the value or @nr_range
>> + * at section memmap populate corresponds to the in-progress range
>> + * being onlined here.
>> + */
>> +static bool compound_section_index(unsigned long start_pfn,
> 
> Oh, I was thinking this would return the actual Nth index number for
> the section within the compound page. 
> A bool is ok too, but then the
> function name would be something like:
> 
> reuse_compound_section()
> 
> ...right?
> 
Yes.

> 
> [..]
>> [...] And here's compound_section_tail_huge_page() (for the last patch in the series):
>>
>>
>> @@ -690,6 +727,33 @@ static struct page * __meminit compound_section_tail_page(unsigned
>> long addr)
>>         return pte_page(*ptep);
>>  }
>>
>> +static struct page * __meminit compound_section_tail_huge_page(unsigned long addr,
>> +                               unsigned long offset, struct dev_pagemap *pgmap)
>> +{
>> +       unsigned long geometry_size = pgmap_geometry(pgmap) << PAGE_SHIFT;
>> +       pmd_t *pmdp;
>> +
>> +       addr -= PAGE_SIZE;
>> +
>> +       /*
>> +        * Assuming sections are populated sequentially, the previous section's
>> +        * page data can be reused.
>> +        */
>> +       pmdp = pmd_off_k(addr);
>> +       if (!pmdp)
>> +               return ERR_PTR(-ENOMEM);
>> +
>> +       /*
>> +        * Reuse the tail pages vmemmap pmd page
>> +        * See layout diagram in Documentation/vm/vmemmap_dedup.rst
>> +        */
>> +       if (offset % geometry_size > PFN_PHYS(PAGES_PER_SECTION))
>> +               return pmd_page(*pmdp);
>> +
Maybe I can drop the geometry_size and just do here:

if (PHYS_PFN(offset) % pgmap_geometry(pgmap) > PAGES_PER_SECTION)

and thus drop the geometry_size variable.

>> +       /* No reusable PMD fallback to PTE tail page*/
>> +       return NULL;
>> +}
>> +
>>  static int __meminit vmemmap_populate_compound_pages(unsigned long start_pfn,
>>                                                      unsigned long start,
>>                                                      unsigned long end, int node,
>> @@ -697,14 +761,22 @@ static int __meminit vmemmap_populate_compound_pages(unsigned long
>> start_pfn,
>>  {
>>         unsigned long offset, size, addr;
>>
>> -       if (compound_section_index(start_pfn, pgmap)) {
>> -               struct page *page;
>> +       if (compound_section_index(start_pfn, pgmap, &offset)) {
>> +               struct page *page, *hpage;
>> +
>> +               hpage = compound_section_tail_huge_page(addr, offset);
>> +               if (IS_ERR(hpage))
>> +                       return -ENOMEM;
>> +               else if (hpage)
> 
> No need for "else" after return... other than that these helpers and
> this arrangement looks good to me.
> 
OK.

  reply	other threads:[~2021-07-28 18:54 UTC|newest]

Thread overview: 78+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-14 19:35 [PATCH v3 00/14] mm, sparse-vmemmap: Introduce " Joao Martins
2021-07-14 19:35 ` [PATCH v3 01/14] memory-failure: fetch compound_head after pgmap_pfn_valid() Joao Martins
2021-07-15  0:17   ` Dan Williams
2021-07-15  2:51   ` [External] " Muchun Song
2021-07-15  6:40     ` Christoph Hellwig
2021-07-15  9:19       ` Muchun Song
2021-07-15 13:17     ` Joao Martins
2021-07-14 19:35 ` [PATCH v3 02/14] mm/page_alloc: split prep_compound_page into head and tail subparts Joao Martins
2021-07-15  0:19   ` Dan Williams
2021-07-15  2:53   ` [External] " Muchun Song
2021-07-15 13:17     ` Joao Martins
2021-07-14 19:35 ` [PATCH v3 03/14] mm/page_alloc: refactor memmap_init_zone_device() page init Joao Martins
2021-07-15  0:20   ` Dan Williams
2021-07-14 19:35 ` [PATCH v3 04/14] mm/memremap: add ZONE_DEVICE support for compound pages Joao Martins
2021-07-15  1:08   ` Dan Williams
2021-07-15 12:52     ` Joao Martins
2021-07-15 13:06       ` Joao Martins
2021-07-15 19:48       ` Dan Williams
2021-07-30 16:13         ` Joao Martins
2021-07-22  0:38       ` Jane Chu
2021-07-22 10:56         ` Joao Martins
2021-07-15 12:59     ` Christoph Hellwig
2021-07-15 13:15       ` Joao Martins
2021-07-15  6:48   ` Christoph Hellwig
2021-07-15 13:15     ` Joao Martins
2021-07-14 19:35 ` [PATCH v3 05/14] mm/sparse-vmemmap: add a pgmap argument to section activation Joao Martins
2021-07-28  5:56   ` Dan Williams
2021-07-28  9:43     ` Joao Martins
2021-07-14 19:35 ` [PATCH v3 06/14] mm/sparse-vmemmap: refactor core of vmemmap_populate_basepages() to helper Joao Martins
2021-07-28  6:04   ` Dan Williams
2021-07-28 10:48     ` Joao Martins
2021-07-14 19:35 ` [PATCH v3 07/14] mm/hugetlb_vmemmap: move comment block to Documentation/vm Joao Martins
2021-07-15  2:47   ` [External] " Muchun Song
2021-07-15 13:16     ` Joao Martins
2021-07-28  6:09   ` Dan Williams
2021-07-14 19:35 ` [PATCH v3 08/14] mm/sparse-vmemmap: populate compound pagemaps Joao Martins
2021-07-28  6:55   ` Dan Williams
2021-07-28 15:35     ` Joao Martins
2021-07-28 18:03       ` Dan Williams
2021-07-28 18:54         ` Joao Martins [this message]
2021-07-28 20:04           ` Joao Martins
2021-07-14 19:35 ` [PATCH v3 09/14] mm/page_alloc: reuse tail struct pages for " Joao Martins
2021-07-28  7:28   ` Dan Williams
2021-07-28 15:56     ` Joao Martins
2021-07-28 16:08       ` Dan Williams
2021-07-28 16:12         ` Joao Martins
2021-07-14 19:35 ` [PATCH v3 10/14] device-dax: use ALIGN() for determining pgoff Joao Martins
2021-07-28  7:29   ` Dan Williams
2021-07-28 15:56     ` Joao Martins
2021-07-14 19:35 ` [PATCH v3 11/14] device-dax: ensure dev_dax->pgmap is valid for dynamic devices Joao Martins
2021-07-28  7:30   ` Dan Williams
2021-07-28 15:56     ` Joao Martins
2021-08-06 12:28       ` Joao Martins
2021-07-14 19:35 ` [PATCH v3 12/14] device-dax: compound pagemap support Joao Martins
2021-07-14 23:36   ` Dan Williams
2021-07-15 12:00     ` Joao Martins
2021-07-27 23:51       ` Dan Williams
2021-07-28  9:36         ` Joao Martins
2021-07-28 18:51           ` Dan Williams
2021-07-28 18:59             ` Joao Martins
2021-07-28 19:03               ` Dan Williams
2021-07-14 19:35 ` [PATCH v3 13/14] mm/gup: grab head page refcount once for group of subpages Joao Martins
2021-07-28 19:55   ` Dan Williams
2021-07-28 20:07     ` Joao Martins
2021-07-28 20:23       ` Dan Williams
2021-08-25 19:10         ` Joao Martins
2021-08-25 19:15           ` Matthew Wilcox
2021-08-25 19:26             ` Joao Martins
2021-07-14 19:35 ` [PATCH v3 14/14] mm/sparse-vmemmap: improve memory savings for compound pud geometry Joao Martins
2021-07-28 20:03   ` Dan Williams
2021-07-28 20:08     ` Joao Martins
2021-07-14 21:48 ` [PATCH v3 00/14] mm, sparse-vmemmap: Introduce compound pagemaps Andrew Morton
2021-07-14 23:47   ` Dan Williams
2021-07-22  2:24   ` Matthew Wilcox
2021-07-22 10:53     ` Joao Martins
2021-07-27 23:23       ` Dan Williams
2021-08-02 10:40         ` Joao Martins
2021-08-02 14:06           ` Dan Williams

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