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Subject: Re: [PATCH 2/2] mm/gup: fix a misnamed "write" argument: should be
 "flags"
To: Ira Weiny <ira.weiny@intel.com>, Aneesh Kumar K.V
	<aneesh.kumar@linux.ibm.com>
CC: "Kirill A. Shutemov" <kirill@shutemov.name>, kbuild test robot
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From: John Hubbard <jhubbard@nvidia.com>
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On 10/14/19 9:45 AM, Ira Weiny wrote:
> On Mon, Oct 14, 2019 at 08:14:04PM +0530, Aneesh Kumar K.V wrote:
>> On 10/14/19 7:22 PM, Kirill A. Shutemov wrote:
>>> On Sun, Oct 13, 2019 at 11:43:10PM -0700, John Hubbard wrote:
>>>> On 10/13/19 11:12 PM, kbuild test robot wrote:
>>>>> Hi John,
>>>>>
>>>>> Thank you for the patch! Yet something to improve:
>>>>>
>>>>> [auto build test ERROR on linus/master]
>>>>> [cannot apply to v5.4-rc3 next-20191011]
>>>>> [if your patch is applied to the wrong git tree, please drop us a note to help
>>>>> improve the system. BTW, we also suggest to use '--base' option to specify the
>>>>> base tree in git format-patch, please see https://stackoverflow.com/a/37406982]
>>>>>
>>>>> url:    https://github.com/0day-ci/linux/commits/John-Hubbard/gup-c-gup_benchmark-c-trivial-fixes-before-the-storm/20191014-114158
>>>>> config: powerpc-defconfig (attached as .config)
>>>>> compiler: powerpc64-linux-gcc (GCC) 7.4.0
>>>>> reproduce:
>>>>>           wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>>>>>           chmod +x ~/bin/make.cross
>>>>>           # save the attached .config to linux build tree
>>>>>           GCC_VERSION=7.4.0 make.cross ARCH=powerpc
>>>>>
>>>>> If you fix the issue, kindly add following tag
>>>>> Reported-by: kbuild test robot <lkp@intel.com>
>>>>>
>>>>> All errors (new ones prefixed by >>):
>>>>>
>>>>>      mm/gup.c: In function 'gup_hugepte':
>>>>>>> mm/gup.c:1990:33: error: 'write' undeclared (first use in this function); did you mean 'writeq'?
>>>>>        if (!pte_access_permitted(pte, write))
>>>>>                                       ^~~~~
>>>>>                                       writeq
>>>>>      mm/gup.c:1990:33: note: each undeclared identifier is reported only once for each function it appears in
>>>>>
>>>>
>>>> OK, so this shows that my cross-compiler test scripts are faulty lately,
>>>> sorry I missed this.
>>>>
>>>> But more importantly, the above missed case is an example of when "write" really
>>>> means "write", as opposed to meaning flags.
>>>>
>>>> Please put this patch on hold or drop it, until we hear from the authors as to how
>>>> they would like to resolve this. I suspect it will end up as something like:
>>>>
>>>> 	bool write = (flags & FOLL_WRITE);
>>>>
>>>> ...perhaps?
>>>
>>> Just use
>>>
>>> 	if (!pte_access_permitted(pte, flags & FOLL_WRITE))
>>>
>>> as we have in gup_pte_range().
>>>
>>> And add:
>>>
>>> Fixes: cbd34da7dc9a ("mm: move the powerpc hugepd code to mm/gup.c")
>>>
>>
>> b798bec4741bdd80224214fdd004c8e52698e42 isn't this the commit that need to
>> be mentioned in the Fixes: tag?
> 
> Yes, and while we are at it the type should probably be changed to unsigned
> int.
> 

OK, I'm posting a v2 with all the above, thanks for these reviews!


thanks,

John Hubbard
NVIDIA