Re: [PATCH 2/3] mm: add bytes_to_page_end() helper

[David Hildenbrand (Arm)]

On 5/18/26 16:29, Thomas Weißschuh wrote:
> On Mon, May 18, 2026 at 02:15:50PM +0100, Lorenzo Stoakes wrote:
>> On Mon, May 18, 2026 at 03:06:16PM +0200, David Hildenbrand (Arm) wrote:
>>>
>>> I think I'd prefer vdso/page.h for something as basic as that.
>>>
>>> But definitely no new header unless really unavoidable :)
>>
>> I just find vdso/page.h an extremely weird beast. what does the VDSO have to do
>> with it and why are we smuggling some basic definitions there...
> 
> The idea behind the vdso/ header namespace is that it can be used from
> vDSO userspace code. A weird middleground between linux/*.h and uapi/linux/*.h.
> Also in a compat vDSO anything depending on BITS_PER_LONG is wrong, and instead
> __BITS_PER_LONG needs to be used. A bunch of kconfig settings, like
> CONFIG_64BIT can also be off. Additionally internal kernel symbols are
> obviously not reachable from vDSO code.
> 
> Regular kernel code should not use the vdso/ namespace but instead use the
> regular linux/ headers, which in turn include the corresponding vdso/ one.

offset_in_page() is that trivial that I don't see how it shouldn't just go next
to PAGE_SIZE / PAGE_MASK, though?

In any case, a new header for this feels very wrong.

-- 
Cheers,

David