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From: "Huang\, Ying" <ying.huang@intel.com>
To: David Rientjes <rientjes@google.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>,
	Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH] mm: Add more comments for MADV_FREE
Date: Wed, 11 Mar 2020 13:22:54 +0800	[thread overview]
Message-ID: <87imjbv51t.fsf@yhuang-dev.intel.com> (raw)
In-Reply-To: <alpine.DEB.2.21.2003102204450.255869@chino.kir.corp.google.com> (David Rientjes's message of "Tue, 10 Mar 2020 22:08:54 -0700")

David Rientjes <rientjes@google.com> writes:

> 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().

Yes.  I think page_is_file_lru() is a better name too.  And whether
tmpfs pages are file cache pages is confusing too.  But I think we can
do that after this patch if others think this is a good idea too.

Best Regards,
Huang, Ying

  reply	other threads:[~2020-03-11  5:23 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
2020-03-11  5:22   ` Huang, Ying [this message]
2020-03-11 14:47     ` Johannes Weiner

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