linux-kernel - Re: [External] [PATCH v2 5/5] hugetlb: convert PageHugeFreed to HPageFreed flag

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Date:   Wed, 20 Jan 2021 18:44:41 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     Mike Kravetz <mike.kravetz@...cle.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        Michal Hocko <mhocko@...nel.org>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        David Hildenbrand <david@...hat.com>,
        Oscar Salvador <osalvador@...e.de>,
        Matthew Wilcox <willy@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [External] [PATCH v2 5/5] hugetlb: convert PageHugeFreed to
 HPageFreed flag

On Wed, Jan 20, 2021 at 9:31 AM Mike Kravetz <mike.kravetz@...cle.com> wrote:
>
> Use new hugetlb specific HPageFreed flag to replace the
> PageHugeFreed interfaces.
>
> Signed-off-by: Mike Kravetz <mike.kravetz@...cle.com>

Reviewed-by: Muchun Song <songmuchun@...edance.com>

> ---
>  include/linux/hugetlb.h |  3 +++
>  mm/hugetlb.c            | 23 ++++-------------------
>  2 files changed, 7 insertions(+), 19 deletions(-)
>
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index ec329b9cc0fc..8fd0970cefdb 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -487,11 +487,13 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
>   *     allocator.  Typically used for migration target pages when no pages
>   *     are available in the pool.  The hugetlb free page path will
>   *     immediately free pages with this flag set to the buddy allocator.
> + * HPG_freed - Set when page is on the free lists.
>   */
>  enum hugetlb_page_flags {
>         HPG_restore_reserve = 0,
>         HPG_migratable,
>         HPG_temporary,
> +       HPG_freed,
>         __NR_HPAGEFLAGS,
>  };
>
> @@ -540,6 +542,7 @@ static inline void ClearHPage##uname(struct page *page)             \
>  HPAGEFLAG(RestoreReserve, restore_reserve)
>  HPAGEFLAG(Migratable, migratable)
>  HPAGEFLAG(Temporary, temporary)
> +HPAGEFLAG(Freed, freed)
>
>  #ifdef CONFIG_HUGETLB_PAGE
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 0d2bfc2b6adc..d5a78aedbfda 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -79,21 +79,6 @@ DEFINE_SPINLOCK(hugetlb_lock);
>  static int num_fault_mutexes;
>  struct mutex *hugetlb_fault_mutex_table ____cacheline_aligned_in_smp;
>
> -static inline bool PageHugeFreed(struct page *head)
> -{
> -       return page_private(head + 4) == -1UL;
> -}
> -
> -static inline void SetPageHugeFreed(struct page *head)
> -{
> -       set_page_private(head + 4, -1UL);
> -}
> -
> -static inline void ClearPageHugeFreed(struct page *head)
> -{
> -       set_page_private(head + 4, 0);
> -}
> -
>  /* Forward declaration */
>  static int hugetlb_acct_memory(struct hstate *h, long delta);
>
> @@ -1043,7 +1028,7 @@ static void enqueue_huge_page(struct hstate *h, struct page *page)
>         list_move(&page->lru, &h->hugepage_freelists[nid]);
>         h->free_huge_pages++;
>         h->free_huge_pages_node[nid]++;
> -       SetPageHugeFreed(page);
> +       SetHPageFreed(page);
>  }
>
>  static struct page *dequeue_huge_page_node_exact(struct hstate *h, int nid)
> @@ -1060,7 +1045,7 @@ static struct page *dequeue_huge_page_node_exact(struct hstate *h, int nid)
>
>                 list_move(&page->lru, &h->hugepage_activelist);
>                 set_page_refcounted(page);
> -               ClearPageHugeFreed(page);
> +               ClearHPageFreed(page);
>                 h->free_huge_pages--;
>                 h->free_huge_pages_node[nid]--;
>                 return page;
> @@ -1474,7 +1459,7 @@ static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
>         spin_lock(&hugetlb_lock);
>         h->nr_huge_pages++;
>         h->nr_huge_pages_node[nid]++;
> -       ClearPageHugeFreed(page);
> +       ClearHPageFreed(page);
>         spin_unlock(&hugetlb_lock);
>  }
>
> @@ -1747,7 +1732,7 @@ int dissolve_free_huge_page(struct page *page)
>                  * We should make sure that the page is already on the free list
>                  * when it is dissolved.
>                  */
> -               if (unlikely(!PageHugeFreed(head))) {
> +               if (unlikely(!HPageFreed(head))) {
>                         rc = -EAGAIN;
>                         goto out;
>                 }
> --
> 2.29.2
>