From: Nikita Danilov <nikita@clusterfs.com>
To: Andrew Morton <akpm@osdl.org>
Cc: pmarques@grupopie.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, hch@infradead.org
Subject: Re: [RFC] per thread page reservation patch
Date: Sat, 08 Jan 2005 02:17:31 +0300 [thread overview]
Message-ID: <m18y74rfqs.fsf@clusterfs.com> (raw)
In-Reply-To: <20050107150315.3c1714a4.akpm@osdl.org> (Andrew Morton's message of "Fri, 7 Jan 2005 15:03:15 -0800")
Andrew Morton <akpm@osdl.org> writes:
> Nikita Danilov <nikita@clusterfs.com> wrote:
>>
>> > And the whole idea is pretty flaky really - how can one precalculate how
>> > much memory an arbitrary md-on-dm-on-loop-on-md-on-NBD stack will want to
>> > use? It really would be better if we could drop the whole patch and make
>> > reiser4 behave more sanely when its writepage is called with for_reclaim=1.
>>
>> Reiser4 doesn't use this for ->writepage(), by the way. This is used by
>> tree balancing code to assure that balancing cannot get -ENOMEM in the
>> middle of tree modification, because undo is _so_ very complicated.
>
> Oh. And that involves performing I/O, yes?
Yes, balancing may read tree or bitmap nodes from the disk.
>
> Why does the filesystem risk going oom during the rebalance anyway? Is it
> doing atomic allocations?
No, just __alloc_pages(GFP_KERNEL, 0, ...) returns NULL. When this
happens, the only thing balancing can do is to panic.
Nikita.
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next prev parent reply other threads:[~2005-01-07 23:17 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20050103011113.6f6c8f44.akpm@osdl.org>
[not found] ` <20050103114854.GA18408@infradead.org>
[not found] ` <41DC2386.9010701@namesys.com>
[not found] ` <1105019521.7074.79.camel@tribesman.namesys.com>
[not found] ` <20050107144644.GA9606@infradead.org>
2005-01-07 17:16 ` Vladimir Saveliev
2005-01-07 18:48 ` Andrew Morton
2005-01-07 20:21 ` Nikita Danilov
2005-01-07 19:05 ` Christoph Hellwig
2005-01-07 19:12 ` Christoph Hellwig
2005-01-07 19:21 ` Robert Love
2005-01-07 20:48 ` Nikita Danilov
2005-01-07 20:54 ` Christoph Hellwig
2005-01-07 21:00 ` Nikita Danilov
2005-01-07 21:07 ` Christoph Hellwig
2005-01-07 19:14 ` Paulo Marques
2005-01-07 19:32 ` Christoph Hellwig
2005-01-07 19:42 ` Andi Kleen
2005-01-07 20:55 ` Nikita Danilov
2005-01-07 21:24 ` Andrew Morton
2005-01-07 21:24 ` Andi Kleen
2005-01-07 22:12 ` Nikita Danilov
2005-01-07 23:03 ` Andrew Morton
2005-01-07 23:17 ` Nikita Danilov [this message]
2005-01-07 23:43 ` Andrew Morton
2005-01-08 12:44 ` Nikita Danilov
2005-01-08 13:43 ` Hugh Dickins
2005-01-09 11:35 ` Marcelo Tosatti
2005-01-09 18:16 ` Nikita Danilov
2005-01-25 16:39 ` reiser4 core patches: [Was: [RFC] per thread page reservation patch] Vladimir Saveliev
2005-01-27 10:37 ` Adrian Bunk
2005-01-27 11:01 ` Christoph Hellwig
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