On Wed, Sep 13, 2023 at 04:40:48PM +0200, Vlastimil Babka wrote: > On 9/11/23 21:41, 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> > > Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx> Thanks! > > @@ -1652,7 +1652,7 @@ int move_freepages_block(struct zone *zone, struct page *page, > > > > /* Do not cross zone boundaries */ > > if (!zone_spans_pfn(zone, start_pfn)) > > - start_pfn = pfn; > > + start_pfn = zone->zone_start_pfn; > > if (!zone_spans_pfn(zone, end_pfn)) > > return 0; > > Culdn't we also adjust end_pfn to zone_end_pfn() so we don't just ignore the > last half-pageblock for no good reason? (or am I missing any?) > Also would stop treating end_pfn as inclusive here and in move_freepages(), > it's rather uncommon. You raise a good point here and in the reply to 5/6. Let me reply to the other email.
