Re: [PATCH 04/10] drm/i915: Fix MAX_ORDER usage in i915_gem_object_get_pages_internal()

From: Kirill A. Shutemov
Date: Wed Mar 15 2023 - 11:28:13 EST


On Wed, Mar 15, 2023 at 02:18:52PM +0000, Tvrtko Ursulin wrote:
>
> On 15/03/2023 11:31, Kirill A. Shutemov wrote:
> > MAX_ORDER is not inclusive: the maximum allocation order buddy allocator
> > can deliver is MAX_ORDER-1.
>
> This looks to be true on inspection:
>
> __alloc_pages():
> ..
> if (WARN_ON_ONCE_GFP(order >= MAX_ORDER, gfp))
>
> So a bit of a misleading name "max".. For the i915 patch:
>
> Acked-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
>
> I don't however see the whole series to understand the context, or how you
> want to handle the individual patches. Is it a tree wide cleanup of the same
> mistake?

The whole patchset can be seen here:

https://lore.kernel.org/all/20230315113133.11326-1-kirill.shutemov@xxxxxxxxxxxxxxx/

The idea is to fix all MAX_ORDER bugs first and then re-define MAX_ORDER
more sensibly.

--
Kiryl Shutsemau / Kirill A. Shutemov