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From: David Rientjes <rientjes@google.com>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	David Hildenbrand <david@redhat.com>,
	Michal Hocko <mhocko@kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Mel Gorman <mgorman@suse.de>, Vlastimil Babka <vbabka@suse.cz>,
	Minchan Kim <minchan@kernel.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Hugh Dickins <hughd@google.com>, Rik van Riel <riel@surriel.com>
Subject: Re: [PATCH] mm: Add more comments for MADV_FREE
Date: Tue, 10 Mar 2020 22:08:54 -0700 (PDT)	[thread overview]
Message-ID: <alpine.DEB.2.21.2003102204450.255869@chino.kir.corp.google.com> (raw)
In-Reply-To: <20200311011117.1656744-1-ying.huang@intel.com>

On Wed, 11 Mar 2020, Huang, Ying wrote:

> diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
> index 6f2fef7b0784..01144dd02a5f 100644
> --- a/include/linux/mm_inline.h
> +++ b/include/linux/mm_inline.h
> @@ -9,10 +9,11 @@
>   * page_is_file_cache - should the page be on a file LRU or anon LRU?
>   * @page: the page to test
>   *
> - * Returns 1 if @page is page cache page backed by a regular filesystem,
> - * or 0 if @page is anonymous, tmpfs or otherwise ram or swap backed.
> - * Used by functions that manipulate the LRU lists, to sort a page
> - * onto the right LRU list.
> + * Returns 1 if @page is page cache page backed by a regular filesystem or
> + * anonymous page lazily freed (e.g. via MADV_FREE).  Returns 0 if @page is
> + * normal anonymous page, tmpfs or otherwise ram or swap backed.  Used by
> + * functions that manipulate the LRU lists, to sort a page onto the right LRU
> + * list.

The function name is misleading: anonymous pages that can be lazily freed 
are not file cache.  This returns 1 because of the question it is asking: 
anonymous lazily freeable pages should be on the file lru, not the anon 
lru.  So before adjusting the comment I'd suggest renaming the function to 
something like page_is_file_lru().

The rest looks fine.

  reply	other threads:[~2020-03-11  5:08 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-11  1:11 Huang, Ying
2020-03-11  5:08 ` David Rientjes [this message]
2020-03-11  5:22   ` Huang, Ying
2020-03-11 14:47     ` Johannes Weiner

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