RE: [PATCH 10/10] powerpc: remove address space overrides using set_fs()

[David Laight]

From: Christoph Hellwig
> Sent: 02 September 2020 13:37
> 
> On Wed, Sep 02, 2020 at 08:15:12AM +0200, Christophe Leroy wrote:
> >> -		return 0;
> >> -	return (size == 0 || size - 1 <= seg.seg - addr);
> >> +	if (addr >= TASK_SIZE_MAX)
> >> +		return false;
> >> +	if (size == 0)
> >> +		return false;
> >
> > __access_ok() was returning true when size == 0 up to now. Any reason to
> > return false now ?
> 
> No, this is accidental and broken.  Can you re-run your benchmark with
> this fixed?

Is TASK_SIZE_MASK defined such that you can do:

	return (addr | size) < TASK_SIZE_MAX) || !size;

    David

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