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From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Matthew Wilcox <willy@infradead.org>
Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 13/25] fs: Add zero_user_large
Date: Fri, 14 Feb 2020 16:52:48 +0300	[thread overview]
Message-ID: <20200214135248.zqcqx3erb4pnlvmu@box> (raw)
In-Reply-To: <20200212041845.25879-14-willy@infradead.org>

On Tue, Feb 11, 2020 at 08:18:33PM -0800, Matthew Wilcox wrote:
> From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
> 
> We can't kmap() a THP, so add a wrapper around zero_user() for large
> pages.

I would rather address it closer to the root: make zero_user_segments()
handle compound pages.

> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>  include/linux/highmem.h | 22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
> 
> diff --git a/include/linux/highmem.h b/include/linux/highmem.h
> index ea5cdbd8c2c3..4465b8784353 100644
> --- a/include/linux/highmem.h
> +++ b/include/linux/highmem.h
> @@ -245,6 +245,28 @@ static inline void zero_user(struct page *page,
>  	zero_user_segments(page, start, start + size, 0, 0);
>  }
>  
> +static inline void zero_user_large(struct page *page,
> +		unsigned start, unsigned size)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < thp_order(page); i++) {
> +		if (start > PAGE_SIZE) {

Off-by-one? >= ?

> +			start -= PAGE_SIZE;
> +		} else {
> +			unsigned this_size = size;
> +
> +			if (size > (PAGE_SIZE - start))
> +				this_size = PAGE_SIZE - start;
> +			zero_user(page + i, start, this_size);
> +			start = 0;
> +			size -= this_size;
> +			if (!size)
> +				break;
> +		}
> +	}
> +}
> +
>  #ifndef __HAVE_ARCH_COPY_USER_HIGHPAGE
>  
>  static inline void copy_user_highpage(struct page *to, struct page *from,
> -- 
> 2.25.0
> 
> 

-- 
 Kirill A. Shutemov

  reply	other threads:[~2020-02-14 13:52 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-12  4:18 [PATCH v2 00/25] Large pages in the page cache Matthew Wilcox
2020-02-12  4:18 ` [PATCH v2 01/25] mm: Use vm_fault error code directly Matthew Wilcox
2020-02-12  7:34   ` Christoph Hellwig
2020-02-12  4:18 ` [PATCH v2 02/25] mm: Optimise find_subpage for !THP Matthew Wilcox
2020-02-12  7:41   ` Christoph Hellwig
2020-02-12 13:02     ` Matthew Wilcox
2020-02-12 17:52       ` Christoph Hellwig
2020-02-13 13:50       ` Kirill A. Shutemov
2020-02-12  4:18 ` [PATCH v2 03/25] mm: Use VM_BUG_ON_PAGE in clear_page_dirty_for_io Matthew Wilcox
2020-02-12  7:38   ` Christoph Hellwig
2020-02-13 13:50   ` Kirill A. Shutemov
2020-02-12  4:18 ` [PATCH v2 04/25] mm: Unexport find_get_entry Matthew Wilcox
2020-02-12  7:37   ` Christoph Hellwig
2020-02-13 13:51   ` Kirill A. Shutemov
2020-02-12  4:18 ` [PATCH v2 05/25] mm: Fix documentation of FGP flags Matthew Wilcox
2020-02-12  7:42   ` Christoph Hellwig
2020-02-12 19:11     ` Matthew Wilcox
2020-02-13 14:00       ` Kirill A. Shutemov
2020-02-13 13:59   ` Kirill A. Shutemov
2020-02-13 14:34     ` Matthew Wilcox
2020-02-12  4:18 ` [PATCH v2 06/25] mm: Allow hpages to be arbitrary order Matthew Wilcox
2020-02-13 14:11   ` Kirill A. Shutemov
2020-02-13 14:30     ` Matthew Wilcox
2020-02-12  4:18 ` [PATCH v2 07/25] mm: Introduce thp_size Matthew Wilcox
2020-02-13 14:19   ` Kirill A. Shutemov
2020-02-12  4:18 ` [PATCH v2 08/25] mm: Introduce thp_order Matthew Wilcox
2020-02-13 14:20   ` Kirill A. Shutemov
2020-02-12  4:18 ` [PATCH v2 09/25] fs: Add a filesystem flag for large pages Matthew Wilcox
2020-02-12  7:43   ` Christoph Hellwig
2020-02-12 14:59     ` Matthew Wilcox
2020-02-12  4:18 ` [PATCH v2 10/25] fs: Introduce i_blocks_per_page Matthew Wilcox
2020-02-12  7:44   ` Christoph Hellwig
2020-02-12 15:05     ` Matthew Wilcox
2020-02-12 17:54       ` Christoph Hellwig
2020-02-13 15:40   ` Kirill A. Shutemov
2020-02-13 16:07     ` Matthew Wilcox
2020-02-12  4:18 ` [PATCH v2 11/25] fs: Make page_mkwrite_check_truncate thp-aware Matthew Wilcox
2020-02-13 15:44   ` Kirill A. Shutemov
2020-02-13 16:26     ` Matthew Wilcox
2020-02-12  4:18 ` [PATCH v2 12/25] mm: Add file_offset_of_ helpers Matthew Wilcox
2020-02-12  7:46   ` Christoph Hellwig
2020-02-12  4:18 ` [PATCH v2 13/25] fs: Add zero_user_large Matthew Wilcox
2020-02-14 13:52   ` Kirill A. Shutemov [this message]
2020-02-14 16:03     ` Matthew Wilcox
2020-02-18 14:16       ` Kirill A. Shutemov
2020-02-18 16:13         ` Matthew Wilcox
2020-02-18 17:10           ` Kirill A. Shutemov
2020-02-18 18:07             ` Matthew Wilcox
2020-02-21 12:42               ` Kirill A. Shutemov
2020-02-12  4:18 ` [PATCH v2 14/25] iomap: Support arbitrarily many blocks per page Matthew Wilcox
2020-02-12  8:05   ` Christoph Hellwig
2020-02-12  4:18 ` [PATCH v2 15/25] iomap: Support large pages in iomap_adjust_read_range Matthew Wilcox
2020-02-12  8:11   ` Christoph Hellwig
2020-02-12  4:18 ` [PATCH v2 16/25] iomap: Support large pages in read paths Matthew Wilcox
2020-02-12  8:13   ` Christoph Hellwig
2020-02-12 17:45     ` Matthew Wilcox
2020-02-12  4:18 ` [PATCH v2 17/25] iomap: Support large pages in write paths Matthew Wilcox
2020-02-12  8:17   ` Christoph Hellwig
2020-02-12  4:18 ` [PATCH v2 18/25] iomap: Inline data shouldn't see large pages Matthew Wilcox
2020-02-12  8:05   ` Christoph Hellwig
2020-02-12  4:18 ` [PATCH v2 19/25] xfs: Support " Matthew Wilcox
2020-02-12  4:18 ` [PATCH v2 20/25] mm: Make prep_transhuge_page return its argument Matthew Wilcox
2020-02-12  4:18 ` [PATCH v2 21/25] mm: Add __page_cache_alloc_order Matthew Wilcox
2020-02-12  4:18 ` [PATCH v2 22/25] mm: Allow large pages to be added to the page cache Matthew Wilcox
2020-02-12  4:18 ` [PATCH v2 23/25] mm: Allow large pages to be removed from " Matthew Wilcox
2020-02-12  4:18 ` [PATCH v2 24/25] mm: Add large page readahead Matthew Wilcox
2020-02-12  4:18 ` [PATCH v2 25/25] mm: Align THP mappings for non-DAX Matthew Wilcox
2020-02-12  7:50   ` Christoph Hellwig

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