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From: Liam Howlett <liam.howlett@oracle.com>
To: Peter Xu <peterx@redhat.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Hugh Dickins <hughd@google.com>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	Miaohe Lin <linmiaohe@huawei.com>,
	David Hildenbrand <david@redhat.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Yang Shi <shy828301@gmail.com>,
	Alistair Popple <apopple@nvidia.com>,
	Matthew Wilcox <willy@infradead.org>,
	"Kirill A . Shutemov" <kirill@shutemov.name>,
	Jerome Glisse <jglisse@redhat.com>,
	Mike Rapoport <rppt@linux.vnet.ibm.com>
Subject: Re: [PATCH v3 3/5] mm: Drop first_index/last_index in zap_details
Date: Thu, 9 Sep 2021 02:54:37 +0000	[thread overview]
Message-ID: <20210909025417.occtqoo6l7x5tnuy@revolver> (raw)
In-Reply-To: <20210908163622.214951-1-peterx@redhat.com>

* Peter Xu <peterx@redhat.com> [210908 12:36]:
> The first_index/last_index parameters in zap_details are actually only used in
> unmap_mapping_range_tree().  At the meantime, this function is only called by
> unmap_mapping_pages() once.  Instead of passing these two variables through the
> whole stack of page zapping code, remove them from zap_details and let them
> simply be parameters of unmap_mapping_range_tree(), which is inlined.
> 
> Reviewed-by: Alistair Popple <apopple@nvidia.com>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>  include/linux/mm.h |  2 --
>  mm/memory.c        | 29 ++++++++++++++++-------------
>  2 files changed, 16 insertions(+), 15 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 73a52aba448f..d1126f731221 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1722,8 +1722,6 @@ extern void user_shm_unlock(size_t, struct ucounts *);
>   */
>  struct zap_details {
>  	struct address_space *check_mapping;	/* Check page->mapping if set */
> -	pgoff_t	first_index;			/* Lowest page->index to unmap */
> -	pgoff_t last_index;			/* Highest page->index to unmap */
>  	struct page *single_page;		/* Locked page to be unmapped */
>  };
>  
> diff --git a/mm/memory.c b/mm/memory.c
> index 7b095f07c4ef..6bba3b9fef7c 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -3321,20 +3321,20 @@ static void unmap_mapping_range_vma(struct vm_area_struct *vma,
>  }
>  
>  static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
> +					    pgoff_t first_index,
> +					    pgoff_t last_index,
>  					    struct zap_details *details)
>  {
>  	struct vm_area_struct *vma;
>  	pgoff_t vba, vea, zba, zea;
>  
> -	vma_interval_tree_foreach(vma, root,
> -			details->first_index, details->last_index) {
> -
> +	vma_interval_tree_foreach(vma, root, first_index, last_index) {
>  		vba = vma->vm_pgoff;
>  		vea = vba + vma_pages(vma) - 1;
> -		zba = details->first_index;
> +		zba = first_index;
>  		if (zba < vba)
>  			zba = vba;
> -		zea = details->last_index;
> +		zea = last_index;
>  		if (zea > vea)
>  			zea = vea;
>  
> @@ -3360,18 +3360,21 @@ void unmap_mapping_page(struct page *page)
>  {
>  	struct address_space *mapping = page->mapping;
>  	struct zap_details details = { };
> +	pgoff_t	first_index, last_index;
>  
>  	VM_BUG_ON(!PageLocked(page));
>  	VM_BUG_ON(PageTail(page));
>  
> +	first_index = page->index;
> +	last_index = page->index + thp_nr_pages(page) - 1;
> +
>  	details.check_mapping = mapping;
> -	details.first_index = page->index;
> -	details.last_index = page->index + thp_nr_pages(page) - 1;
>  	details.single_page = page;
>  
>  	i_mmap_lock_write(mapping);
>  	if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
> -		unmap_mapping_range_tree(&mapping->i_mmap, &details);
> +		unmap_mapping_range_tree(&mapping->i_mmap, first_index,
> +					 last_index, &details);
>  	i_mmap_unlock_write(mapping);
>  }
>  
> @@ -3390,17 +3393,17 @@ void unmap_mapping_page(struct page *page)
>  void unmap_mapping_pages(struct address_space *mapping, pgoff_t start,
>  		pgoff_t nr, bool even_cows)
>  {
> +	pgoff_t	first_index = start, last_index = start + nr - 1;

Nit: If you respin, can first_index and last_index be two lines please?

>  	struct zap_details details = { };
>  
>  	details.check_mapping = even_cows ? NULL : mapping;
> -	details.first_index = start;
> -	details.last_index = start + nr - 1;
> -	if (details.last_index < details.first_index)
> -		details.last_index = ULONG_MAX;

Nit: Maybe throw a comment about this being overflow check, if you
respin.

> +	if (last_index < first_index)
> +		last_index = ULONG_MAX;
>  
>  	i_mmap_lock_write(mapping);
>  	if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
> -		unmap_mapping_range_tree(&mapping->i_mmap, &details);
> +		unmap_mapping_range_tree(&mapping->i_mmap, first_index,
> +					 last_index, &details);
>  	i_mmap_unlock_write(mapping);
>  }
>  
> -- 
> 2.31.1
> 

Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>

  reply	other threads:[~2021-09-09  2:55 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-08 16:35 [PATCH v3 0/5] mm: A few cleanup patches around zap, shmem and uffd Peter Xu
2021-09-08 16:35 ` [PATCH v3 1/5] mm/shmem: Unconditionally set pte dirty in mfill_atomic_install_pte Peter Xu
2021-09-08 16:36 ` [PATCH v3 2/5] mm: Clear vmf->pte after pte_unmap_same() returns Peter Xu
2021-09-08 16:36 ` [PATCH v3 3/5] mm: Drop first_index/last_index in zap_details Peter Xu
2021-09-09  2:54   ` Liam Howlett [this message]
2021-09-09 18:13     ` Peter Xu
2021-09-08 16:36 ` [PATCH v3 4/5] mm: Add zap_skip_check_mapping() helper Peter Xu
2021-09-09  1:16   ` Alistair Popple
2021-09-08 16:36 ` [PATCH v3 5/5] mm: Add ZAP_FLAG_SKIP_SWAP and zap_flags Peter Xu
2021-09-15  2:25   ` Alistair Popple
2021-09-15  2:52     ` Peter Xu
2021-09-15  3:21       ` Alistair Popple
2021-09-15  4:01         ` Peter Xu
2021-09-14 16:37 ` [PATCH v3 0/5] mm: A few cleanup patches around zap, shmem and uffd Peter Xu

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