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To: William Lee Irwin III <wli@holomorphy.com>
Cc: Andrea Arcangeli <andrea@suse.de>, Andrew Morton <akpm@osdl.org>,
       linux-kernel@vger.kernel.org, Robert_Hentosh@Dell.com,
       Con Kolivas <kernel@kolivas.org>
Subject: Re: [PATCH][1/2] adjust dirty threshold for lowmem-only mappings
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From: Nikita Danilov <nikita@clusterfs.com>
Date: Sun, 26 Dec 2004 01:03:14 +0300
In-Reply-To: <20041225190710.GZ771@holomorphy.com> (William Lee Irwin, III's
 message of "Sat, 25 Dec 2004 11:07:10 -0800")
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William Lee Irwin III <wli@holomorphy.com> writes:

> On Sat, 25 Dec 2004, Andrea Arcangeli wrote:
>>> the first place? If that happens it means you're under a lowmem
>>> shortage, something you apparently ruled out when you said
>>> lowmem_reserve couldn't help your workload.
>
> On Sat, Dec 25, 2004 at 12:59:10PM -0500, Rik van Riel wrote:
>> Let me explain a 3rd time:
> [...]
>> If you have any more questions as to why the bug happens, don't
>> hesitate to ask and I'll explain you why this problem happens.
>
> This is an old and well-known problem.
>
> Lifting the artificial lowmem restrictions on blockdev mappings
> (thereby nuking mapping->gfp_mask altogether) would resolve a number of
> problems, not that anything making that much sense could ever happen.

mapping->gfp_mask is used for other things beyond specifying a
zonelist. For example, file systems want all allocations inside a
transaction to be done with GFP_NOFS, which forces GFP_NOFS in
mapping->gfp_mask of meta-data address_spaces.

>
>
> -- wli

Nikita.