Re: [PATCH] mm: page_alloc: remove stale CMA guard code

[Mel Gorman <mgorman@techsingularity.net>]

On Thu, Aug 24, 2023 at 11:38:21AM -0400, Johannes Weiner wrote:
> In the past, movable allocations could be disallowed from CMA through
> PF_MEMALLOC_PIN. As CMA pages are funneled through the MOVABLE
> pcplist, this required filtering that cornercase during allocations,
> such that pinnable allocations wouldn't accidentally get a CMA page.
> 
> However, since 8e3560d963d2 ("mm: honor PF_MEMALLOC_PIN for all
> movable pages"), PF_MEMALLOC_PIN automatically excludes
> __GFP_MOVABLE. Once again, MOVABLE implies CMA is allowed.
> 
> Remove the stale filtering code. Also remove a stale comment that was
> introduced as part of the filtering code, because the filtering let
> order-0 pages fall through to the buddy allocator. See 1d91df85f399
> ("mm/page_alloc: handle a missing case for
> memalloc_nocma_{save/restore} APIs") for context. The comment's been
> obsolete since the introduction of the explicit ALLOC_HIGHATOMIC flag
> in eb2e2b425c69 ("mm/page_alloc: explicitly record high-order atomic
> allocations in alloc_flags").
> 
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

Acked-by: Mel Gorman <mgorman@techsingularity.net>

-- 
Mel Gorman
SUSE Labs