From: Andrew Morton <akpm@linux-foundation.org>
Subject: Re: page eviction from the buddy cache
Date: Wed, 24 Apr 2013 14:41:30 -0700
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Cc: Hugh Dickins <hughd@google.com>,
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To: "Theodore Ts'o" <tytso@mit.edu>
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On Wed, 24 Apr 2013 10:26:50 -0400 "Theodore Ts'o" <tytso@mit.edu> wrote:

> On Tue, Apr 23, 2013 at 03:00:08PM -0700, Andrew Morton wrote:
> > That should fix things for now.  Although it might be better to just do
> > 
> >  	mark_page_accessed(page);	/* to SetPageReferenced */
> >  	lru_add_drain();		/* to SetPageLRU */
> > 
> > Because a) this was too early to decide that the page is
> > super-important and b) the second touch of this page should have a
> > mark_page_accessed() in it already.
> 
> The question is do we really want to put lru_add_drain() into the ext4
> file system code?  That seems to pushing some fairly mm-specific
> knowledge into file system code.  I'll do this if I have to do, but
> wouldn't be better if this was pushed into mark_page_accessed(), or
> some other new API was exported by the mm subsystem?

Sure, that would be daft.  We'd add a new
mark_page_accessed_right_now_dont_use_this() to mm/swap.c