Messages in this thread | | | Date | Wed, 8 Feb 2023 11:13:57 +0100 | Subject | Re: [RFC v3 2/4] mm: move PG_slab flag to page_type | From | David Hildenbrand <> |
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On 08.02.23 10:44, Mike Rapoport wrote: > On Fri, Feb 03, 2023 at 05:04:01PM +0100, David Hildenbrand wrote: >> On 30.01.23 06:11, Matthew Wilcox wrote: >>> On Mon, Jan 30, 2023 at 01:34:59PM +0900, Hyeonggon Yoo wrote: >>>>> Seems like quite some changes to page_type to accomodate SLAB, which is >>>>> hopefully going away soon(TM). Could we perhaps avoid that? >>>> >>>> If it could be done with less changes, I'll try to avoid that. >>> >>> Let me outline the idea I had for removing PG_slab: >>> >>> Observe that PG_reserved and PG_slab are mutually exclusive. Also, >> >> I recall that there are SetPageReserved() calls on pages allocated via slab. > > I did a quick scan, and it seems that all allocated reserved pages come > from alloc_pages() or vmalloc(). >
Thanks for checking, good that my memory was wrong :)
> BTW, looking at the current usage of SetPageReserved, it seems that some > are bogus/historical and some would justify a different page type if we are > to have 15 bits for PG_kernel.
I remember raising in the past that something like PG_hole might be helpful.
I also recall that most SetPageReserved usage in drivers is to make ioremap happy. PG_ioremappable or smth like that would be better.
So yes, that would even help to cleanup the existing PG_reserved usage.
-- Thanks,
David / dhildenb
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