Re: [patch] 'virtual => physical page mapping cache',vcache-2.5.38-B8

Andrew Morton (akpm@digeo.com)
Fri, 27 Sep 2002 11:35:05 -0700


Alan Cox wrote:
>
> On Fri, 2002-09-27 at 18:53, Ingo Molnar wrote:
> >
> > On Fri, 27 Sep 2002, Chris Wedgwood wrote:
> >
> > > O_DIRECT is allow to break if someone does something silly :) [...]
> >
> > to DMA into a page that does not belong to the process anymore? I doubt
> > that.
>
> Try doing a truncate on a file as an O_DIRECT write is occuring.
> Scribbling into pages you dont own is the least of your problems.

O_DIRECT writes operate under i_sem, which provides exclusion
from trucate. Do you know something which I don't??
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