linux-kernel - Re: [PATCH v3 07/30] kho: add interfaces to unpreserve folios and physical memory ranges

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Message-ID: <20250818135509.GK802098@nvidia.com>
Date: Mon, 18 Aug 2025 10:55:09 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Mike Rapoport <rppt@...nel.org>
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Subject: Re: [PATCH v3 07/30] kho: add interfaces to unpreserve folios and
 physical memory ranges

On Fri, Aug 15, 2025 at 12:12:10PM +0300, Mike Rapoport wrote:
> > Which is perhaps another comment, if this __get_free_pages() is going
> > to be a common pattern (and I guess it will be) then the API should be
> > streamlined alot more:
> > 
> >  void *kho_alloc_preserved_memory(gfp, size);
> >  void kho_free_preserved_memory(void *);
> 
> This looks backwards to me. KHO should not deal with memory allocation,
> it's responsibility to preserve/restore memory objects it supports.

Then maybe those are luo_ helpers

But having users open code __get_free_pages() and convert to/from
struct page, phys, etc is not a great idea.

The use case is simply to get some memory to preserve, it should work
in terms of void *. We don't support slab today so this has to be
emulated with full pages, but this detail should not leak out of the
API.

Jason