linux-kernel - Re: [PATCH v1 13/13] kho: Introduce high-level memory allocation API

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Message-ID: <aRdVvxF2bDVjSN8f@kernel.org>
Date: Fri, 14 Nov 2025 18:15:59 +0200
From: Mike Rapoport <rppt@...nel.org>
To: Pasha Tatashin <pasha.tatashin@...een.com>
Cc: akpm@...ux-foundation.org, bhe@...hat.com, jasonmiu@...gle.com,
	arnd@...db.de, coxu@...hat.com, dave@...ilevsky.ca,
	ebiggers@...gle.com, graf@...zon.com, kees@...nel.org,
	linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
	linux-mm@...ck.org
Subject: Re: [PATCH v1 13/13] kho: Introduce high-level memory allocation API

On Fri, Nov 14, 2025 at 10:53:58AM -0500, Pasha Tatashin wrote:
> Currently, clients of KHO must manually allocate memory (e.g., via
> alloc_pages), calculate the page order, and explicitly call
> kho_preserve_folio(). Similarly, cleanup requires separate calls to
> unpreserve and free the memory.
> 
> Introduce a high-level API to streamline this common pattern:
> 
> - kho_alloc_preserve(size): Allocates physically contiguous, zeroed
>   memory and immediately marks it for preservation.
> - kho_free_unpreserve(ptr, size): Unpreserves and frees the memory
>   in the current kernel.
> - kho_free_restore(ptr, size): Restores the struct page state of
>   preserved memory in the new kernel and immediately frees it to the
>   page allocator.

It would have been nice to have it before patch 3 (Preserve FDT folio only
once during initialization) and use kho_alloc_preserve() for KHO's own FDT.

> Signed-off-by: Pasha Tatashin <pasha.tatashin@...een.com>
> ---
>  include/linux/kexec_handover.h     |  22 +++++--
>  kernel/liveupdate/kexec_handover.c | 101 +++++++++++++++++++++++++++++
>  2 files changed, 116 insertions(+), 7 deletions(-)

-- 
Sincerely yours,
Mike.