linux-kernel - Re: [PATCH v2 01/12] mm: Make pagecache tagged lookups return only head pages

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20200929091348.GI10896@quack2.suse.cz>
Date:   Tue, 29 Sep 2020 11:13:48 +0200
From:   Jan Kara <jack@...e.cz>
To:     "Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        Hugh Dickins <hughd@...gle.com>,
        William Kucharski <william.kucharski@...cle.com>,
        Johannes Weiner <hannes@...xchg.org>, Jan Kara <jack@...e.cz>,
        Yang Shi <yang.shi@...ux.alibaba.com>,
        Dave Chinner <dchinner@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 01/12] mm: Make pagecache tagged lookups return only
 head pages

On Mon 14-09-20 14:00:31, Matthew Wilcox (Oracle) wrote:
> Pagecache tags are used for dirty page writeback.  Since dirtiness is
> tracked on a per-THP basis, we only want to return the head page rather
> than each subpage of a tagged page.  All the filesystems which use huge
> pages today are in-memory, so there are no tagged huge pages today.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>

Looks good to me. You can add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  mm/filemap.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/mm/filemap.c b/mm/filemap.c
> index f5fda3038782..7d8cf1a25628 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1968,7 +1968,7 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
>  EXPORT_SYMBOL(find_get_pages_contig);
>  
>  /**
> - * find_get_pages_range_tag - find and return pages in given range matching @tag
> + * find_get_pages_range_tag - Find and return head pages matching @tag.
>   * @mapping:	the address_space to search
>   * @index:	the starting page index
>   * @end:	The final page index (inclusive)
> @@ -1976,8 +1976,8 @@ EXPORT_SYMBOL(find_get_pages_contig);
>   * @nr_pages:	the maximum number of pages
>   * @pages:	where the resulting pages are placed
>   *
> - * Like find_get_pages, except we only return pages which are tagged with
> - * @tag.   We update @index to index the next page for the traversal.
> + * Like find_get_pages(), except we only return head pages which are tagged
> + * with @tag.   We update @index to index the next page for the traversal.
>   *
>   * Return: the number of pages which were found.
>   */
> @@ -2011,9 +2011,9 @@ unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
>  		if (unlikely(page != xas_reload(&xas)))
>  			goto put_page;
>  
> -		pages[ret] = find_subpage(page, xas.xa_index);
> +		pages[ret] = page;
>  		if (++ret == nr_pages) {
> -			*index = xas.xa_index + 1;
> +			*index = page->index + thp_nr_pages(page);
>  			goto out;
>  		}
>  		continue;
> -- 
> 2.28.0
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR