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From: Andrew Morton <akpm@linux-foundation.org>
To: "Russ Cox" <rsc@swtch.com>
Cc: "Miklos Szeredi" <miklos@szeredi.hu>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] fix quadratic behavior of shrink_dcache_parent()
Date: Fri, 9 Feb 2007 16:40:18 -0800	[thread overview]
Message-ID: <20070209164018.e4d29be0.akpm@linux-foundation.org> (raw)
In-Reply-To: <ee9e417a0702091623t1ccf55b8wb05b64b9c51474a6@mail.gmail.com>

On Fri, 9 Feb 2007 19:23:31 -0500
"Russ Cox" <rsc@swtch.com> wrote:

> > "The file system mounted on /tmp/z in the example contains 2^50
> > directories".   heh.
> >
> > I do wonder how realistic this problem is in real life.
> 
> That's a fair concern, although I was trying this as part
> of evaluating how much someone could hose a system
> if we let them mount arbitrary FUSE servers.  And the
> answer is: they could make it completely unusable,
> requiring reboot.
> 
> I ran a later test that printed how deep it got into
> the file tree and it was only a few hundred thousand
> if I recall correctly.  A determined attacker might even
> manage to do this in a normal file system.
> 
> But sure, it's not a common case.  ;-)

Well that's a good point - sometimes people do crazy things on purpose.  We
were all University students once ;) 

The patches look nice and as I said, potentially of some use for memory
reclaim.  But I hope that someone who has worked on dcache.c more recently
than I has time to apply a toothcomb to this work.


  reply	other threads:[~2007-02-10  0:40 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-09 22:01 [PATCH] fix quadratic behavior of shrink_dcache_parent() Miklos Szeredi
2007-02-10  0:00 ` Andrew Morton
2007-02-10  0:23   ` Russ Cox
2007-02-10  0:40     ` Andrew Morton [this message]
2007-02-10  8:46     ` Miklos Szeredi
2007-02-10 10:51       ` Andi Kleen
2007-02-10 12:57       ` Russ Cox
2007-02-11 12:13         ` Miklos Szeredi

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