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From: Muchun Song <songmuchun@bytedance.com>
To: Jonathan Corbet <corbet@lwn.net>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com,
	dave.hansen@linux.intel.com, luto@kernel.org,
	Peter Zijlstra <peterz@infradead.org>,
	viro@zeniv.linux.org.uk,
	Andrew Morton <akpm@linux-foundation.org>,
	paulmck@kernel.org, mchehab+huawei@kernel.org,
	pawan.kumar.gupta@linux.intel.com,
	Randy Dunlap <rdunlap@infradead.org>,
	oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de,
	Mina Almasry <almasrymina@google.com>,
	David Rientjes <rientjes@google.com>
Cc: linux-doc@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	Linux Memory Management List <linux-mm@kvack.org>,
	linux-fsdevel@vger.kernel.org
Subject: Re: [RFC PATCH 21/24] mm/hugetlb: Merge pte to huge pmd only for gigantic page
Date: Sun, 20 Sep 2020 17:59:01 +0800	[thread overview]
Message-ID: <CAMZfGtWXr0A3ymf_trBmUggRudbZbhfwNCJWSHZdkK9JeBY1fg@mail.gmail.com> (raw)
In-Reply-To: <20200915125947.26204-22-songmuchun@bytedance.com>

On Tue, Sep 15, 2020 at 9:03 PM Muchun Song <songmuchun@bytedance.com> wrote:
>
> Merge pte to huge pmd if it has ever been split. Now only support
> gigantic page which's vmemmap pages size is an integer multiple of
> PMD_SIZE. This is the simplest case to handle.
>
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> ---
>  include/linux/hugetlb.h |   7 +++
>  mm/hugetlb.c            | 104 +++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 109 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index e3aa192f1c39..c56df0da7ae5 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -611,6 +611,13 @@ static inline bool vmemmap_pmd_huge(pmd_t *pmd)
>  }
>  #endif
>
> +#ifndef vmemmap_pmd_mkhuge
> +static inline pmd_t vmemmap_pmd_mkhuge(struct page *page)
> +{
> +       return pmd_mkhuge(mk_pmd(page, PAGE_KERNEL));
> +}
> +#endif
> +
>  #ifndef VMEMMAP_HPAGE_SHIFT
>  #define VMEMMAP_HPAGE_SHIFT            PMD_SHIFT
>  #endif
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 28c154679838..3ca36e259b4e 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1759,6 +1759,62 @@ static void __remap_huge_page_pte_vmemmap(struct page *reuse, pte_t *ptep,
>         }
>  }
>
> +static void __replace_huge_page_pte_vmemmap(pte_t *ptep, unsigned long start,
> +                                           unsigned int nr, struct page *huge,
> +                                           struct list_head *free_pages)
> +{
> +       unsigned long addr;
> +       unsigned long end = start + (nr  << PAGE_SHIFT);
> +
> +       for (addr = start; addr < end; addr += PAGE_SIZE, ptep++) {
> +               struct page *page;
> +               pte_t old = *ptep;
> +               pte_t entry;
> +
> +               prepare_vmemmap_page(huge);
> +
> +               entry = mk_pte(huge++, PAGE_KERNEL);
> +               VM_WARN_ON(!pte_present(old));
> +               page = pte_page(old);
> +               list_add(&page->lru, free_pages);
> +
> +               set_pte_at(&init_mm, addr, ptep, entry);
> +       }
> +}
> +
> +static void replace_huge_page_pmd_vmemmap(pmd_t *pmd, unsigned long start,
> +                                         struct page *huge,
> +                                         struct list_head *free_pages)
> +{
> +       unsigned long end = start + VMEMMAP_HPAGE_SIZE;
> +
> +       flush_cache_vunmap(start, end);
> +       __replace_huge_page_pte_vmemmap(pte_offset_kernel(pmd, start), start,
> +                                       VMEMMAP_HPAGE_NR, huge, free_pages);
> +       flush_tlb_kernel_range(start, end);
> +}
> +
> +static pte_t *merge_vmemmap_pte(pmd_t *pmdp, unsigned long addr)
> +{
> +       pte_t *pte;
> +       struct page *page;
> +
> +       pte = pte_offset_kernel(pmdp, addr);
> +       page = pte_page(*pte);
> +       set_pmd(pmdp, vmemmap_pmd_mkhuge(page));
> +
> +       return pte;
> +}
> +
> +static void merge_huge_page_pmd_vmemmap(pmd_t *pmd, unsigned long start,
> +                                       struct page *huge,
> +                                       struct list_head *free_pages)
> +{
> +       replace_huge_page_pmd_vmemmap(pmd, start, huge, free_pages);
> +       pte_free_kernel(&init_mm, merge_vmemmap_pte(pmd, start));
> +       flush_tlb_kernel_range(start, start + VMEMMAP_HPAGE_SIZE);
> +}
> +
>  static inline void alloc_vmemmap_pages(struct hstate *h, struct list_head *list)
>  {
>         int i;
> @@ -1772,6 +1828,15 @@ static inline void alloc_vmemmap_pages(struct hstate *h, struct list_head *list)
>         }
>  }
>
> +static inline void dissolve_compound_page(struct page *page, unsigned int order)
> +{
> +       int i;
> +       unsigned int nr_pages = 1 << order;
> +
> +       for (i = 1; i < nr_pages; i++)
> +               set_page_refcounted(page + i);
> +}
> +
>  static void alloc_huge_page_vmemmap(struct hstate *h, struct page *head)
>  {
>         pmd_t *pmd;
> @@ -1791,10 +1856,45 @@ static void alloc_huge_page_vmemmap(struct hstate *h, struct page *head)
>                                     __remap_huge_page_pte_vmemmap);
>         if (!freed_vmemmap_hpage_dec(pmd_page(*pmd)) && pmd_split(pmd)) {
>                 /*
> -                * Todo:
> -                * Merge pte to huge pmd if it has ever been split.
> +                * Merge pte to huge pmd if it has ever been split. Now only
> +                * support gigantic page which's vmemmap pages size is an
> +                * integer multiple of PMD_SIZE. This is the simplest case
> +                * to handle.
>                  */
>                 clear_pmd_split(pmd);
> +
> +               if (IS_ALIGNED(nr_vmemmap(h), VMEMMAP_HPAGE_NR)) {
> +                       unsigned long addr = (unsigned long)head;
> +                       unsigned long end = addr + nr_vmemmap_size(h);
> +
> +                       spin_unlock(ptl);
> +
> +                       for (; addr < end; addr += VMEMMAP_HPAGE_SIZE) {
> +                               void *to;
> +                               struct page *page;
> +
> +                               page = alloc_pages(GFP_VMEMMAP_PAGE & ~__GFP_NOFAIL,
> +                                                  VMEMMAP_HPAGE_ORDER);
> +                               if (!page)
> +                                       goto out;

Here forget to call dissolve_compound_page().

+                               dissolve_compound_page(page,
+                                                      VMEMMAP_HPAGE_ORDER);

> +
> +                               to = page_to_virt(page);
> +                               memcpy(to, (void *)addr, VMEMMAP_HPAGE_SIZE);
> +
> +                               /*
> +                                * Make sure that any data that writes to the
> +                                * @to is made visible to the physical page.
> +                                */
> +                               flush_kernel_vmap_range(to, VMEMMAP_HPAGE_SIZE);
> +
> +                               merge_huge_page_pmd_vmemmap(pmd++, addr, page,
> +                                                           &remap_pages);
> +                       }
> +
> +out:
> +                       free_vmemmap_page_list(&remap_pages);
> +                       return;
> +               }
>         }
>         spin_unlock(ptl);
>  }
> --
> 2.20.1
>


-- 
Yours,
Muchun

  reply	other threads:[~2020-09-20  9:59 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-15 12:59 [RFC PATCH 00/24] mm/hugetlb: Free some vmemmap pages of hugetlb page Muchun Song
2020-09-15 12:59 ` [RFC PATCH 01/24] mm/memory_hotplug: Move bootmem info registration API to bootmem_info.c Muchun Song
2020-09-29 22:46   ` Mike Kravetz
2020-09-15 12:59 ` [RFC PATCH 02/24] mm/memory_hotplug: Move {get,put}_page_bootmem() " Muchun Song
2020-09-29 23:30   ` Mike Kravetz
2020-09-15 12:59 ` [RFC PATCH 03/24] mm/hugetlb: Introduce a new config HUGETLB_PAGE_FREE_VMEMMAP Muchun Song
2020-09-16  2:13   ` Randy Dunlap
2020-09-29 23:41   ` Mike Kravetz
2020-09-30  2:56     ` [External] " Muchun Song
2020-09-15 12:59 ` [RFC PATCH 04/24] mm/hugetlb: Register bootmem info when CONFIG_HUGETLB_PAGE_FREE_VMEMMAP Muchun Song
2020-09-15 12:59 ` [RFC PATCH 05/24] mm/hugetlb: Introduce nr_free_vmemmap_pages in the struct hstate Muchun Song
2020-09-30 22:41   ` Mike Kravetz
2020-10-01  2:57     ` [External] " Muchun Song
2020-09-15 12:59 ` [RFC PATCH 06/24] mm/hugetlb: Introduce pgtable allocation/freeing helpers Muchun Song
2020-09-15 12:59 ` [RFC PATCH 07/24] mm/hugetlb: Add freeing unused vmemmap pages support for x86 Muchun Song
2020-09-15 12:59 ` [RFC PATCH 08/24] mm/bootmem_info: Introduce {free,prepare}_vmemmap_page() Muchun Song
2020-09-15 12:59 ` [RFC PATCH 09/24] x86/mm: Introduce VMEMMAP_SIZE/VMEMMAP_END macro Muchun Song
2020-09-15 12:59 ` [RFC PATCH 10/24] mm/hugetlb: Free the vmemmap pages associated with each hugetlb page Muchun Song
2020-09-15 12:59 ` [RFC PATCH 11/24] mm/hugetlb: Add vmemmap_pmd_huge macro for x86 Muchun Song
2020-09-15 12:59 ` [RFC PATCH 12/24] mm/hugetlb: Defer freeing of hugetlb pages Muchun Song
2020-09-15 12:59 ` [RFC PATCH 13/24] mm/hugetlb: Allocate the vmemmap pages associated with each hugetlb page Muchun Song
2020-09-15 12:59 ` [RFC PATCH 14/24] mm/hugetlb: Introduce remap_huge_page_pmd_vmemmap helper Muchun Song
2020-09-15 12:59 ` [RFC PATCH 15/24] mm/hugetlb: Use PG_slab to indicate split pmd Muchun Song
2020-09-15 12:59 ` [RFC PATCH 16/24] mm/hugetlb: Support freeing vmemmap pages of gigantic page Muchun Song
2020-09-15 12:59 ` [RFC PATCH 17/24] mm/hugetlb: Add a BUILD_BUG_ON to check if struct page size is a power of two Muchun Song
2020-09-15 12:59 ` [RFC PATCH 18/24] mm/hugetlb: Clear PageHWPoison on the non-error memory page Muchun Song
2020-09-15 12:59 ` [RFC PATCH 19/24] mm/hugetlb: Flush work when dissolving hugetlb page Muchun Song
2020-09-15 12:59 ` [RFC PATCH 20/24] mm/hugetlb: Add a kernel parameter hugetlb_free_vmemmap Muchun Song
2020-09-16  2:10   ` Randy Dunlap
2020-09-16  2:50     ` [External] " Muchun Song
2020-09-15 12:59 ` [RFC PATCH 21/24] mm/hugetlb: Merge pte to huge pmd only for gigantic page Muchun Song
2020-09-20  9:59   ` Muchun Song [this message]
2020-09-15 12:59 ` [RFC PATCH 22/24] mm/hugetlb: Implement vmemmap_pmd_mkhuge macro Muchun Song
2020-09-15 12:59 ` [RFC PATCH 23/24] mm/hugetlb: Gather discrete indexes of tail page Muchun Song
2020-09-15 12:59 ` [RFC PATCH 24/24] mm/hugetlb: Add BUILD_BUG_ON to catch invalid usage of tail struct page Muchun Song
2020-09-15 14:32 ` [RFC PATCH 00/24] mm/hugetlb: Free some vmemmap pages of hugetlb page Matthew Wilcox
2020-09-15 14:53   ` Dave Hansen
2020-09-15 15:28   ` [External] " Muchun Song
2020-09-15 15:42     ` Matthew Wilcox
2020-09-15 17:32       ` Muchun Song
2020-09-15 17:39         ` Matthew Wilcox
2020-09-15 18:03           ` Muchun Song
2020-09-15 18:15             ` Matthew Wilcox
2020-09-16  2:45               ` Muchun Song
2020-09-29 21:58 ` Mike Kravetz
2020-09-30  3:13   ` Matthew Wilcox
2020-10-07 21:12   ` Mike Kravetz
2020-10-09  4:13     ` [External] " Muchun Song

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