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Date: Mon, 4 May 2009 23:21:17 +0400
From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>, mingo@elte.hu, mel@csn.ul.ie,
       linux-kernel@vger.kernel.org, penberg@cs.helsinki.fi, riel@redhat.com,
       rientjes@google.com, xemul@openvz.org
Subject: Re: [PATCH -tip] mm: introduce __GFP_PANIC modifier
Message-ID: <20090504192117.GB31176@lenovo>
References: <20090504122740.GH4173@lenovo> <20090504131311.GA23330@elte.hu> <20090504131638.GJ4173@lenovo> <alpine.DEB.1.10.0905040940490.9553@qirst.com> <20090504115335.9bc08587.akpm@linux-foundation.org>
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[Andrew Morton - Mon, May 04, 2009 at 11:53:35AM -0700]
| On Mon, 4 May 2009 09:47:45 -0400 (EDT)
| Christoph Lameter <cl@linux.com> wrote:
| 
| > 
| > 
| > Could you try to avoid consuming another GFP flag? __GFP_BITS_SHIFT is
| > used elsewhere to figure out where to put miscellanous flags into the gfp
| > mask. This is pretty limited right now and so the patch does work.
| 
| hm, yes, there are seven bits left.
| 
| afaict bit 3 (0x08) is unused?
| 
| Is __GFP_PANIC very useful?  I expect it will permit a very small code
| saving at a relatively small number of callsites, all of which are
| __init anyway?
| 

Actually the issue with possible NULL deref already fixed in -tip
tree commit 9a8709d. There was rather an idea on what will be more
convenient -- call for __GFP_NOFAIL or use BUG_ON on allocation
failure or call kmalloc with __GFP_PANIC and forget about if it could
fail :). Since Christoph said that it's discommended to introduce
new flag -- I'm fine with that.

	-- Cyrill