Re: [PATCH] drm/tests/drm_buddy: avoid 64-bit calculation

["Arnd Bergmann" <arnd@arndb.de>]

On Mon, Feb 19, 2024, at 12:22, Christian König wrote:
> Am 17.02.24 um 02:31 schrieb Randy Dunlap:
>> On 2/16/24 12:24, Arnd Bergmann wrote:
>>> From: Arnd Bergmann <arnd@arndb.de>
>>>
>>> The newly added drm_test_buddy_alloc_contiguous() test fails to link on
>>> 32-bit targets because of inadvertent 64-bit calculations:
>>>
>>> ERROR: modpost: "__aeabi_uldivmod" [drivers/gpu/drm/tests/drm_buddy_test.ko] undefined!
>>> ERROR: modpost: "__aeabi_ldivmod" [drivers/gpu/drm/tests/drm_buddy_test.ko] undefined!
>>>
>>> >From what I can tell, the numbers cannot possibly overflow a 32-bit size,
>>> so use different types for these.
>>>
>>> I noticed that the function has another possible flaw in that is mixes
>>> what it calls pages with 4KB units. This is a big confusing at best,
>>> or possibly broken when built on machines with larger pages.
>>>
>>> Fixes: a64056bb5a32 ("drm/tests/drm_buddy: add alloc_contiguous test")
>>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>> Tested-by: Randy Dunlap <rdunlap@infradead.org>
>
> I've just pushed a similar patch Mathew came up a bit earlier to 
> drm-misc-fixes.
>
> Sorry for the noise, I have to catch up on picking up patches for 
> misc-fixes and misc-next.

Ok, thanks.

Have you looked at how this code works for larger values of PAGE_SIZE?
Is there any need to change other things or will this work with the
hardcoded 4KB chunks?

     Arnd