Re: [rfc][patch] mm: half-fix page tail zeroing on write problem

[Nick Piggin]

On Fri, Feb 02, 2007 at 05:29:06PM +1100, Neil Brown wrote:
> On Friday February 2, npiggin@xxxxxxx wrote:
> > Hi,
> > 
> > For no important reason, I've again looked at those zeroing patches that
> > Neil did a while back. I've always thought that a simple
> > `write(fd, NULL, size)` would cause the same sorts of problems.
> 
> Yeh, but who in their right mind would do that???
> Oh, you did :-)

Well that's the test-case. Obviously not many people do it, but that's
all the more reason to be careful about correct behaviour.

> I cannot see why you make a change to fault_in_pages_writeable.  Is it
> just for symmetry?

Yes.

> For the rest, it certainly makes sense to return an early -EFAULT if
> you cannot fault in the page.

I think so.

Thanks,
Nick
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