linux-kernel - Re: [PATCH v3 07/16] mm/rmap: pass rmap flags to hugepage_add_anon

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Date:   Tue, 12 Apr 2022 10:37:15 +0200
From:   Vlastimil Babka <vbabka@...e.cz>
To:     David Hildenbrand <david@...hat.com>, linux-kernel@...r.kernel.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Hugh Dickins <hughd@...gle.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        David Rientjes <rientjes@...gle.com>,
        Shakeel Butt <shakeelb@...gle.com>,
        John Hubbard <jhubbard@...dia.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Yang Shi <shy828301@...il.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Matthew Wilcox <willy@...radead.org>,
        Jann Horn <jannh@...gle.com>, Michal Hocko <mhocko@...nel.org>,
        Nadav Amit <namit@...are.com>, Rik van Riel <riel@...riel.com>,
        Roman Gushchin <guro@...com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Peter Xu <peterx@...hat.com>,
        Donald Dutile <ddutile@...hat.com>,
        Christoph Hellwig <hch@....de>,
        Oleg Nesterov <oleg@...hat.com>, Jan Kara <jack@...e.cz>,
        Liang Zhang <zhangliang5@...wei.com>,
        Pedro Gomes <pedrodemargomes@...il.com>,
        Oded Gabbay <oded.gabbay@...il.com>, linux-mm@...ck.org
Subject: Re: [PATCH v3 07/16] mm/rmap: pass rmap flags to
 hugepage_add_anon_rmap()

On 3/29/22 18:04, David Hildenbrand wrote:
> Let's prepare for passing RMAP_EXCLUSIVE, similarly as we do for
> page_add_anon_rmap() now. RMAP_COMPOUND is implicit for hugetlb
> pages and ignored.
> 
> Signed-off-by: David Hildenbrand <david@...hat.com>

Acked-by: Vlastimil Babka <vbabka@...e.cz>

> ---
>  include/linux/rmap.h | 2 +-
>  mm/migrate.c         | 3 ++-
>  mm/rmap.c            | 9 ++++++---
>  3 files changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/rmap.h b/include/linux/rmap.h
> index aa734d2e2b01..f47bc937c383 100644
> --- a/include/linux/rmap.h
> +++ b/include/linux/rmap.h
> @@ -191,7 +191,7 @@ void page_add_file_rmap(struct page *, struct vm_area_struct *,
>  void page_remove_rmap(struct page *, struct vm_area_struct *,
>  		bool compound);
>  void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,
> -		unsigned long address);
> +		unsigned long address, rmap_t flags);
>  void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *,
>  		unsigned long address);
>  
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 436f0ec2da03..48db9500d20e 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -232,7 +232,8 @@ static bool remove_migration_pte(struct folio *folio,
>  			pte = pte_mkhuge(pte);
>  			pte = arch_make_huge_pte(pte, shift, vma->vm_flags);
>  			if (folio_test_anon(folio))
> -				hugepage_add_anon_rmap(new, vma, pvmw.address);
> +				hugepage_add_anon_rmap(new, vma, pvmw.address,
> +						       RMAP_NONE);
>  			else
>  				page_dup_file_rmap(new, true);
>  			set_huge_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 71bf881da2a6..b972eb8f351b 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -2347,9 +2347,11 @@ void rmap_walk_locked(struct folio *folio, const struct rmap_walk_control *rwc)
>   * The following two functions are for anonymous (private mapped) hugepages.
>   * Unlike common anonymous pages, anonymous hugepages have no accounting code
>   * and no lru code, because we handle hugepages differently from common pages.
> + *
> + * RMAP_COMPOUND is ignored.
>   */
> -void hugepage_add_anon_rmap(struct page *page,
> -			    struct vm_area_struct *vma, unsigned long address)
> +void hugepage_add_anon_rmap(struct page *page, struct vm_area_struct *vma,
> +			    unsigned long address, rmap_t flags)
>  {
>  	struct anon_vma *anon_vma = vma->anon_vma;
>  	int first;
> @@ -2359,7 +2361,8 @@ void hugepage_add_anon_rmap(struct page *page,
>  	/* address might be in next vma when migration races vma_adjust */
>  	first = atomic_inc_and_test(compound_mapcount_ptr(page));
>  	if (first)
> -		__page_set_anon_rmap(page, vma, address, 0);
> +		__page_set_anon_rmap(page, vma, address,
> +				     !!(flags & RMAP_EXCLUSIVE));
>  }
>  
>  void hugepage_add_new_anon_rmap(struct page *page,