Re: [PATCH v4 5/7] mm: thp: split huge page to any lower order pages (except order-1).

From: Zi Yan
Date: Tue Feb 13 2024 - 17:17:44 EST


On 13 Feb 2024, at 17:05, Luis Chamberlain wrote:

> On Tue, Feb 13, 2024 at 04:55:18PM -0500, Zi Yan wrote:
>> From: Zi Yan <ziy@xxxxxxxxxx>
>> Order-1 folio is not supported because _deferred_list, which is used by
>> partially mapped folios, is stored in subpage 2 and an order-1 folio only
>> has subpage 0 and 1.
>
> The LBS patches has the patch from Matthew which enables and allowed us
> to successfully test order 1. So this restriction could be dropped if
> that gets merged.

OK. But it only applies to file-backed folios IIUC. Anonymous folios still
cannot be split to order-1.

--
Best Regards,
Yan, Zi

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