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

From: Christoph Hellwig <[email-masked]>
Date: Wed, 2 Sep 2020 14:36:46 +0200

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?