linux-kernel - Re: [PATCH] proc: fixup map

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Date:   Mon, 12 Nov 2018 14:35:39 -0200
From:   Rafael David Tinoco <rafael.tinoco@...aro.org>
To:     Cyrill Gorcunov <gorcunov@...il.com>,
        Alexey Dobriyan <adobriyan@...il.com>
Cc:     rafael.tinoco@...aro.org, akpm@...ux-foundation.org,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        shuah@...nel.org
Subject: Re: [PATCH] proc: fixup map_files test on arm

On 11/12/18 1:55 PM, Cyrill Gorcunov wrote:
> On Mon, Nov 12, 2018 at 05:14:57PM +0300, Alexey Dobriyan wrote:
> ...
>>>>   int main(void)
>>>>   {
>>>>   	const unsigned int PAGE_SIZE = sysconf(_SC_PAGESIZE);
>>>> +#ifdef __arm__
>>>> +	unsigned long va = 2 * PAGE_SIZE;
>>>> +#else
>>>> +	unsigned long va = 0;
>>>> +#endif
> ...
>>>
>>> I have sent a patch removing proc-self-map-files-002 AND making 001 to use as a
>>> HINT for mmap (MAP_FIXED) *at least*  *(2 * PAGE_SIZE), which would, likely,
>>> attend all  architectures, avoiding trying to make the test specific to one,
>>> and, still, test the symlinks for issues (like bad chars, spaces, so on).
>>
>> If the goal is to test the lowest address then going for 2*PAGE_SIZE is
>> a mistake.
>>
>> Which BTW hints to add a test for the highest address.
>>
>>> Both tests (001 and 002) have pretty much the same code, while they could have 2
>>> tests in a single code, using kselftest framework. Is NULL hint + MAP_FIXED
>>> something imperative for this test ? Why not to have all in a single test ?
>>
>> I dislike tests which lump everything together into one process.
>>
>>> Are you keeping the NULL hint just to test mmap, apart" from the core of
>>> this test ?
> 
> Guys, lets simply stick with Alexey's patch. I personnally think that
> testing mappings should be a separate test in vm/, but seriously this
> took too long already :) If Alexey's patch fixes the problem with arm
> I think we're fine.
> 

Fine for me. It works in armhf.

Tested-by: Rafael David Tinoco <rafael.tinoco@...aro.org>

Note: Maybe you should amend the patch and cast "va" in mmap() to avoid:

In file included from proc-self-map-files-002.c:7:
/usr/include/arm-linux-gnueabihf/sys/mman.h:57:14: note: expected ‘void 
*’ but argument is of type ‘long unsigned int’
  extern void *mmap (void *__addr, size_t __len, int __prot,

--
Rafael D. Tinoco
Linaro Kernel Validation