Re: [PATCH v2 6/6] alloc_tag: config to store page allocation tag refs in page flags

Kent Overstreet
2024-09-04T16:37:56Z

On Wed, Sep 04, 2024 at 05:35:49PM GMT, Matthew Wilcox wrote:
> On Wed, Sep 04, 2024 at 09:18:01AM -0700, Suren Baghdasaryan wrote:
> > I'm not sure I understand your suggestion, Matthew. We allocate a
> > folio and need to store a reference to the tag associated with the
> > code that allocated that folio. We are not operating with ranges here.
> > Are you suggesting to use a maple tree instead of page_ext to store
> > this reference?
>
> I'm saying that a folio has a physical address. So you can use a physical
> address as an index into a maple tree to store additional information
> instead of using page_ext or trying to hammer the additional information
> into struct page somewhere.

Ah, thanks, that makes more sense.

But it would add a lot of overhead to the page alloc/free paths...