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Date: Mon, 14 May 2007 14:06:19 -0400
From: Theodore Tso <tytso@mit.edu>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Fengguang Wu <fengguang.wu@gmail.com>, linux-kernel@vger.kernel.org,
       linux-mm@kvack.org, Rik van Riel <riel@redhat.com>,
       "linux-ext4@vger.kernel.org" <linux-ext4@vger.kernel.org>
Subject: Re: [PATCH] resolve duplicate flag no for PG_lazyfree
Message-ID: <20070514180618.GB9399@thunk.org>
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On Sun, May 13, 2007 at 10:46:30PM -0700, Andrew Morton wrote:
> otoh, the intersection between pages which are PageBooked() and pages which
> are PageLazyFree() should be zreo, so it'd be good to actually formalise
> this reuse within the ext4 patches.
> 
> otoh2, PageLazyFree() could have reused PG_owner_priv_1.
> 
> Rik, Ted: any thoughts?  We do need to scrimp on page flags: when we
> finally run out, we're screwed.

It makes sense to me.  PG_lazyfree is currently only in -mm, right?  I
don't see it in my git tree.  It would probably would be a good idea
to make sure that we check to add some sanity checking code if it
isn't there already that PG_lazyfree isn't already set when try to set
PG_lazyfree (just in case there is a bug in the future which causes
the should-never-happen case of trying lazy free a PageBooked page).

						- Ted
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