linux-kernel - Re: [PATCH 0/4] Remove get_kernel

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Message-ID: <CAFA6WYN+3inY6MYrMFY0qhmifCYtj_immFMFN6jC1BamQCYGWQ@mail.gmail.com>
Date:   Mon, 3 Oct 2022 14:55:02 +0530
From:   Sumit Garg <sumit.garg@...aro.org>
To:     ira.weiny@...el.com
Cc:     Jens Wiklander <jens.wiklander@...aro.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Fabio M. De Francesco" <fmdefrancesco@...il.com>,
        op-tee@...ts.trustedfirmware.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [PATCH 0/4] Remove get_kernel_pages()

Hi Ira,

On Sun, 2 Oct 2022 at 05:53, <ira.weiny@...el.com> wrote:
>
> From: Ira Weiny <ira.weiny@...el.com>
>
> get_kernel_pages() only had one caller [shm_get_kernel_pages()] which did not
> need the functionality it provided.  Furthermore, it called kmap_to_page()
> which we are looking to removed.
>
> Alter shm_get_kernel_pages() to no longer call get_kernel_pages() and remove
> get_kernel_pages().  Along the way it was noted that shm_get_kernel_pages()
> does not have any need to support vmalloc'ed addresses either.  Remove that
> functionality to clean up the logic.
>
> This series also fixes and uses is_kmap_addr().

>From the above description, I am failing to see the motivation behind
this change. Can you elaborate here?

Also, since you are targeting to remove kmap_to_page(), is there any
alternative way to support highmem for future TEE bus drivers? As I
can see higmem being enabled for multiple Arm defconfigs [1] which can
also support TEE (an example which already does it:
arch/arm/configs/imx_v6_v7_defconfig).

[1] git grep CONFIG_HIGHMEM arch/arm/

-Sumit

>
> Ira Weiny (4):
>   highmem: Enhance is_kmap_addr() to check kmap_local_page() mappings
>   tee: Remove vmalloc page support
>   tee: Remove call to get_kernel_pages()
>   mm: Remove get_kernel_pages()
>
>  drivers/tee/tee_shm.c            | 41 ++++++++++++--------------------
>  include/linux/highmem-internal.h |  5 +++-
>  include/linux/mm.h               |  2 --
>  mm/swap.c                        | 30 -----------------------
>  4 files changed, 19 insertions(+), 59 deletions(-)
>
>
> base-commit: 274d7803837da78dfc911bcda0d593412676fc20
> --
> 2.37.2
>