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Date: Sun, 9 Feb 2014 12:34:18 -0500
From: Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [patch 02/10] fs: cachefiles: use add_to_page_cache_lru()
Message-ID: <20140209173418.GH4407@cmpxchg.org>
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To: Rafael Aquini <aquini@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, Andi Kleen <andi@firstfloor.org>, Andrea Arcangeli <aarcange@redhat.com>, Bob Liu <bob.liu@oracle.com>, Christoph Hellwig <hch@infradead.org>, Dave Chinner <david@fromorbit.com>, Greg Thelen <gthelen@google.com>, Hugh Dickins <hughd@google.com>, Jan Kara <jack@suse.cz>, KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>, Luigi Semenzato <semenzato@google.com>, Mel Gorman <mgorman@suse.de>, Metin Doslu <metin@citusdata.com>, Michel Lespinasse <walken@google.com>, Minchan Kim <minchan.kim@gmail.com>, Ozgun Erdogan <ozgun@citusdata.com>, Peter Zijlstra <peterz@infradead.org>, Rik van Riel <riel@redhat.com>, Roman Gushchin <klamm@yandex-team.ru>, Ryan Mallon <rmallon@gmail.com>, Tejun Heo <tj@kernel.org>, Vlastimil Babka <vbabka@suse.cz>, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org

On Sat, Feb 08, 2014 at 09:43:35AM -0200, Rafael Aquini wrote:
> On Mon, Feb 03, 2014 at 07:53:34PM -0500, Johannes Weiner wrote:
> > This code used to have its own lru cache pagevec up until a0b8cab3
> > ("mm: remove lru parameter from __pagevec_lru_add and remove parts of
> > pagevec API").  Now it's just add_to_page_cache() followed by
> > lru_cache_add(), might as well use add_to_page_cache_lru() directly.
> >
> 
> Just a heads-up, here: take a look at https://lkml.org/lkml/2014/2/7/587

Ah, yes.  That patch replaced a private pagevec, which consumes the
references you pass in, with add_to_page_cache_lru(), which gets its
own references.

My patch changes

    add_to_page_cache()
    lru_cache_add()

to

    add_to_page_cache_lru()
      add_to_page_cache()
      lru_cache_add()

so the refcounting does not change for the caller.

Thanks for pointing it out, though, it never hurts to double check
stuff like that.

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