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From: "Manfred Spraul" <manfred@colorfullife.com>
To: "Alan Cox" <alan@lxorguk.ukuu.org.uk>
Cc: "Daniel Jacobowitz" <dan@debian.org>, <linux-kernel@vger.kernel.org>,
        "Andrew Morton" <akpm@zip.com.au>
In-Reply-To: <E16VJu7-0001w0-00@the-village.bc.nu>
Subject: Re: [PATCH?] Crash in 2.4.17/ptrace
Date: Mon, 28 Jan 2002 23:07:30 +0100
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From: "Alan Cox" <alan@lxorguk.ukuu.org.uk>
> > For framebuffers addresses, there is no page structure, and then the
> > page reference count updates read/write to random memory.
>
> If it is a physical pci bus object why do we need to refcount it,
> surely "no page" is ok. Its just up to the driver not to do anything
> stupid and the core code to honour the pci/pci transfer quirks (or
> when faced with a hard one just say "no")
>
With multi-threaded apps, munmap() during O_DIRECT is possible. vma
structures don't contain a reference count.

For ptrace, taking the physical address from the PTE and ioremapping it
temporarily would work, but ...

--
    Manfred


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