Re: [PATCH 4/6] mm: page_alloc: fix move_freepages_block() range error

[Mel Gorman]

On Mon, Sep 11, 2023 at 03:41:45PM -0400, Johannes Weiner wrote:
> When a block is partially outside the zone of the cursor page, the
> function cuts the range to the pivot page instead of the zone
> start. This can leave large parts of the block behind, which
> encourages incompatible page mixing down the line (ask for one type,
> get another), and thus long-term fragmentation.
> 
> This triggers reliably on the first block in the DMA zone, whose
> start_pfn is 1. The block is stolen, but everything before the pivot
> page (which was often hundreds of pages) is left on the old list.
> 
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>

Oops

Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>

-- 
Mel Gorman
SUSE Labs