Re: [RFC 1/5] drop page reference on remove_from_page_cache

From: KAMEZAWA Hiroyuki
Date: Sun Dec 19 2010 - 20:59:18 EST


On Sat, 18 Dec 2010 02:13:36 +0900
Minchan Kim <minchan.kim@xxxxxxxxx> wrote:

> Now we add page reference on add_to_page_cache but doesn't drop it
> in remove_from_page_cache. Such asymmetric makes confusing about
> page reference so that caller should notice it and comment why they
> release page reference. It's not good API.
>
> Long time ago, Hugh tried it[1] but gave up of reason which
> reiser4's drop_page had to unlock the page between removing it from
> page cache and doing the page_cache_release. But now the situation is
> changed. I think at least things in current mainline doesn't have any
> obstacles. The problem is fs or somethings out of mainline.
> If it has done such thing like reiser4, this patch could be a problem.
>
> Do anyone know the such things? Do we care about things out of mainline?
>
> Note :
> The comment of remove_from_page_cache make by copy & paste & s/swap/page/
> from delete_from_swap_cache.
>
> [1] http://lkml.org/lkml/2004/10/24/140
>
> Cc: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: linux-mm@xxxxxxxxx
> Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx>

I like this.
Reviewd-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>

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