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 sd7pBOQG 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0, page, NULL, NULL, SPLIT_TYPE_UNIFORM); > > > > We're trying to get rid of uniform splits. Why do you need this to be > > uniform? I looked into this bit more - we do want a uniform split here. What we want is to split the THP into 512 4k pages here. Per the doc for __split_unmapped_folio: 3590 * @split_at: in buddy allocator like split, the folio containing @split_at 3591 * will be split until its order becomes @new_order. I think this implies some of the pages may still be a higher order which is not desired behavior for this usage. Matt > > It’s very possible we’re doing this incorrectly due to a lack of core MM > experience. I believe Zi Yan suggested this approach (use > __split_unmapped_folio) a while back. > > Let me start by explaining what we’re trying to do and see if there’s a > better suggestion for how to accomplish it. > > Would SPLIT_TYPE_NON_UNIFORM split work here? Or do you have another > suggestion on how to split the folio aside from __split_unmapped_folio? > > This covers the case where a GPU device page was allocated as a THP > (e.g., we call zone_device_folio_init with an order of 9). Later, this > page is freed/unmapped and then reallocated for a CPU VMA that is > smaller than a THP (e.g., we’d allocate either 4KB or 64KB based on > CPU VMA size alignment). At this point, we need to split the device > folio so we can migrate data into 4KB device pages. > > Would SPLIT_TYPE_NON_UNIFORM work here? Or do you have another > suggestion for splitting the folio aside from __split_unmapped_folio? > > Matt