From: Ira Weiny <ira.weiny@intel.com>
To: Sumit Garg <sumit.garg@linaro.org>
Cc: Jens Wiklander <jens.wiklander@linaro.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Fabio M. De Francesco" <fmdefrancesco@gmail.com>,
<op-tee@lists.trustedfirmware.org>,
<linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>
Subject: Re: [PATCH 0/4] Remove get_kernel_pages()
Date: Mon, 3 Oct 2022 08:22:09 -0700 [thread overview]
Message-ID: <Yzr+IU2IMkvJQqbu@iweiny-mobl> (raw)
In-Reply-To: <CAFA6WYN+3inY6MYrMFY0qhmifCYtj_immFMFN6jC1BamQCYGWQ@mail.gmail.com>
On Mon, Oct 03, 2022 at 02:55:02PM +0530, Sumit Garg wrote:
> Hi Ira,
>
> On Sun, 2 Oct 2022 at 05:53, <ira.weiny@intel.com> wrote:
> >
> > From: Ira Weiny <ira.weiny@intel.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?
Al Viro found[1] that kmap_to_page() is broken. But not only was it broken but
it presents confusion over how highmem should be used because kmap() and
friends should not be used for 'long term' mappings.
[1] https://lore.kernel.org/lkml/YzSSl1ItVlARDvG3@ZenIV
>
> 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).
With TEE how are the highmem pages used? Right now the code does not seem to
use any user pages. So I can't really say how this should work. Why does the
kernel need a mapping of those pages?
Ira
>
> [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
> >
next prev parent reply other threads:[~2022-10-03 15:22 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-02 0:23 [PATCH 0/4] Remove get_kernel_pages() ira.weiny
2022-10-02 0:23 ` [PATCH 1/4] highmem: Enhance is_kmap_addr() to check kmap_local_page() mappings ira.weiny
2022-10-02 0:23 ` [PATCH 2/4] tee: Remove vmalloc page support ira.weiny
2022-10-03 6:41 ` Jens Wiklander
2022-10-03 6:57 ` Sumit Garg
2022-10-05 3:28 ` Phil Chang (張世勳)
2022-10-06 6:23 ` Sumit Garg
2022-10-06 18:19 ` Ira Weiny
2022-10-06 18:20 ` Linus Torvalds
2022-10-07 8:12 ` Jens Wiklander
2022-12-16 0:41 ` Ira Weiny
2022-12-16 5:09 ` Sumit Garg
2022-12-16 8:45 ` Sumit Garg
2022-12-16 7:06 ` Christoph Hellwig
2022-10-10 7:42 ` Christoph Hellwig
2022-10-10 17:20 ` Linus Torvalds
2022-10-10 17:57 ` Al Viro
2022-10-02 0:23 ` [PATCH 3/4] tee: Remove call to get_kernel_pages() ira.weiny
2022-10-02 0:46 ` Al Viro
2022-10-02 2:30 ` Ira Weiny
2022-10-03 7:17 ` Christoph Hellwig
2022-10-03 15:02 ` Ira Weiny
2022-10-02 0:23 ` [PATCH 4/4] mm: Remove get_kernel_pages() ira.weiny
2022-10-03 20:28 ` John Hubbard
2022-10-03 9:25 ` [PATCH 0/4] " Sumit Garg
2022-10-03 15:22 ` Ira Weiny [this message]
2022-10-04 6:32 ` Sumit Garg
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=Yzr+IU2IMkvJQqbu@iweiny-mobl \
--to=ira.weiny@intel.com \
--cc=akpm@linux-foundation.org \
--cc=fmdefrancesco@gmail.com \
--cc=jens.wiklander@linaro.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=op-tee@lists.trustedfirmware.org \
--cc=sumit.garg@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).