Re: [PATCH v2 0/4] Remove get_kernel_pages()

Re: [PATCH v2 0/4] Remove get_kernel_pages()

[Jens Wiklander]

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On Mon, Feb 13, 2023 at 11:02:52AM -0800, Linus Torvalds wrote:
> On Mon, Feb 13, 2023 at 7:02 AM Jens Wiklander
> <jens.wiklander@linaro.org> wrote:
> >
> > Sure, I'll take it. The timing is a bit unfortunate, it's likely too
> > close to the merge window to be included there. However, I'll pick it
> > up and add it to linux-next so it's ready for the 6.4 merge window.
> 
> With this boeing almost all code removal, I'm perfectly fine taking it
> in the upcoming merge window.

OK, thank you.

Cheers,
Jens

Re: [PATCH v2 0/4] Remove get_kernel_pages()

[Ira Weiny]

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Jens Wiklander wrote:
> Hi Ira,
> 
> On Fri, Feb 10, 2023 at 9:28 PM Ira Weiny <ira.weiny@intel.com> wrote:
> >
> > Ira Weiny wrote:
> > > Sumit Garg wrote:
> > > > On Sat, 4 Feb 2023 at 09:36, Ira Weiny <ira.weiny@intel.com> wrote:
> > > > >
> > > > > Sumit,
> > > > >
> > > > > I did not see a follow up on this series per your last email.[1]  I'd like to
> > > > > move forward with getting rid of kmap_to_page().  So Hopefully this can land
> > > > > and you can build on this rather than the other way around?
> > > >
> > > > Apologies Ira for keeping you waiting. Actually I was fully involved
> > > > with other high priority work with my upstream review backlog
> > > > increasing. So I wasn't able to devote time to this work. Sure I will
> > > > rebase my work on top of your changes.
> > >
> > > No problem on my end.  I just wanted to ensure that I did not miss
> > > something.
> >
> > Andrew, can I get an ack on patches 1 and 4 for this series?  I realized
> > that perhaps I was not clear on my expectations of this series.  I was
> > thinking this would be easiest to go through the tee subsystem tree.
> >
> > Sumit or Jens, is that ok with you all?
> 
> Sure, I'll take it. The timing is a bit unfortunate, it's likely too
> close to the merge window to be included there. However, I'll pick it
> up and add it to linux-next so it's ready for the 6.4 merge window.

6.4 is fine with me.

Thanks everyone!
Ira

Re: [PATCH v2 0/4] Remove get_kernel_pages()

[Linus Torvalds]

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On Mon, Feb 13, 2023 at 7:02 AM Jens Wiklander
<jens.wiklander@linaro.org> wrote:
>
> Sure, I'll take it. The timing is a bit unfortunate, it's likely too
> close to the merge window to be included there. However, I'll pick it
> up and add it to linux-next so it's ready for the 6.4 merge window.

With this boeing almost all code removal, I'm perfectly fine taking it
in the upcoming merge window.

           Linus

Re: [PATCH v2 0/4] Remove get_kernel_pages()

[Ira Weiny]

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Sumit Garg wrote:
> On Sat, 4 Feb 2023 at 09:36, Ira Weiny <ira.weiny@intel.com> wrote:
> >
> > Sumit,
> >
> > I did not see a follow up on this series per your last email.[1]  I'd like to
> > move forward with getting rid of kmap_to_page().  So Hopefully this can land
> > and you can build on this rather than the other way around?
> 
> Apologies Ira for keeping you waiting. Actually I was fully involved
> with other high priority work with my upstream review backlog
> increasing. So I wasn't able to devote time to this work. Sure I will
> rebase my work on top of your changes.

No problem on my end.  I just wanted to ensure that I did not miss
something.

Thanks for the reviews!
Ira

> 
> -Sumit
> 
> >
> > All,
> >
> > Al Viro found[2] that kmap_to_page() is broken.  But not only is it broken, it
> > presents confusion over how highmem should be used because kmap() and friends
> > should not be used for 'long term' mappings.
> >
> > get_kernel_pages() is a caller of kmap_to_page().  It only has one caller
> > [shm_get_kernel_pages()] which does not need the functionality.
> >
> > 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 is_kmap_addr() and uses it to ensure no kmap addresses
> > slip in later.
> >
> > [1] https://lore.kernel.org/all/CAFA6WYMqEVDVW-ifoh-V9ni1zntYdes8adQKf2XXAUpqdaW53w(a)mail.gmail.com/
> > [2] https://lore.kernel.org/lkml/YzSSl1ItVlARDvG3(a)ZenIV
> >
> > To: Sumit Garg <sumit.garg@linaro.org>
> > To: Andrew Morton <akpm@linux-foundation.org>
> > Cc: "Al Viro" <viro@zeniv.linux.org.uk>
> > Cc: "Christoph Hellwig" <hch@lst.de>
> > Cc: linux-kernel(a)vger.kernel.org
> > Cc: op-tee(a)lists.trustedfirmware.org
> > Cc: linux-mm(a)kvack.org
> > Cc: Jens Wiklander <jens.wiklander@linaro.org>
> > Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
> > Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> >
> > ---
> > Changes in v2:
> > - Al Viro: Avoid allocating the kiov.
> > - Sumit: Update cover letter to clarify the motivation behind removing
> >   get_kernel_pages()
> > - Link to v1: https://lore.kernel.org/r/20221002002326.946620-1-ira.weiny(a)intel.com
> >
> > ---
> > 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            | 37 ++++++++++---------------------------
> >  include/linux/highmem-internal.h |  5 ++++-
> >  include/linux/mm.h               |  2 --
> >  mm/swap.c                        | 30 ------------------------------
> >  4 files changed, 14 insertions(+), 60 deletions(-)
> > ---
> > base-commit: 0136d86b78522bbd5755f8194c97a987f0586ba5
> > change-id: 20230203-get_kernel_pages-199342cfba79
> >
> > Best regards,
> > --
> > Ira Weiny <ira.weiny@intel.com>

Re: [PATCH v2 0/4] Remove get_kernel_pages()

[Ira Weiny]

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Ira Weiny wrote:
> Sumit Garg wrote:
> > On Sat, 4 Feb 2023 at 09:36, Ira Weiny <ira.weiny@intel.com> wrote:
> > >
> > > Sumit,
> > >
> > > I did not see a follow up on this series per your last email.[1]  I'd like to
> > > move forward with getting rid of kmap_to_page().  So Hopefully this can land
> > > and you can build on this rather than the other way around?
> > 
> > Apologies Ira for keeping you waiting. Actually I was fully involved
> > with other high priority work with my upstream review backlog
> > increasing. So I wasn't able to devote time to this work. Sure I will
> > rebase my work on top of your changes.
> 
> No problem on my end.  I just wanted to ensure that I did not miss
> something.

Andrew, can I get an ack on patches 1 and 4 for this series?  I realized
that perhaps I was not clear on my expectations of this series.  I was
thinking this would be easiest to go through the tee subsystem tree.

Sumit or Jens, is that ok with you all?

Thanks,
Ira

Re: [PATCH v2 0/4] Remove get_kernel_pages()

[Jens Wiklander]

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Hi Ira,

On Fri, Feb 10, 2023 at 9:28 PM Ira Weiny <ira.weiny@intel.com> wrote:
>
> Ira Weiny wrote:
> > Sumit Garg wrote:
> > > On Sat, 4 Feb 2023 at 09:36, Ira Weiny <ira.weiny@intel.com> wrote:
> > > >
> > > > Sumit,
> > > >
> > > > I did not see a follow up on this series per your last email.[1]  I'd like to
> > > > move forward with getting rid of kmap_to_page().  So Hopefully this can land
> > > > and you can build on this rather than the other way around?
> > >
> > > Apologies Ira for keeping you waiting. Actually I was fully involved
> > > with other high priority work with my upstream review backlog
> > > increasing. So I wasn't able to devote time to this work. Sure I will
> > > rebase my work on top of your changes.
> >
> > No problem on my end.  I just wanted to ensure that I did not miss
> > something.
>
> Andrew, can I get an ack on patches 1 and 4 for this series?  I realized
> that perhaps I was not clear on my expectations of this series.  I was
> thinking this would be easiest to go through the tee subsystem tree.
>
> Sumit or Jens, is that ok with you all?

Sure, I'll take it. The timing is a bit unfortunate, it's likely too
close to the merge window to be included there. However, I'll pick it
up and add it to linux-next so it's ready for the 6.4 merge window.

Thanks,
Jens

[PATCH v2 0/4] Remove get_kernel_pages()

[Ira Weiny]

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Sumit,

I did not see a follow up on this series per your last email.[1]  I'd like to
move forward with getting rid of kmap_to_page().  So Hopefully this can land
and you can build on this rather than the other way around?

All,

Al Viro found[2] that kmap_to_page() is broken.  But not only is it broken, it
presents confusion over how highmem should be used because kmap() and friends
should not be used for 'long term' mappings.

get_kernel_pages() is a caller of kmap_to_page().  It only has one caller
[shm_get_kernel_pages()] which does not need the functionality.

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 is_kmap_addr() and uses it to ensure no kmap addresses
slip in later.

[1] https://lore.kernel.org/all/CAFA6WYMqEVDVW-ifoh-V9ni1zntYdes8adQKf2XXAUpqdaW53w(a)mail.gmail.com/
[2] https://lore.kernel.org/lkml/YzSSl1ItVlARDvG3(a)ZenIV

To: Sumit Garg <sumit.garg@linaro.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Al Viro" <viro@zeniv.linux.org.uk>
Cc: "Christoph Hellwig" <hch@lst.de>
Cc: linux-kernel(a)vger.kernel.org
Cc: op-tee(a)lists.trustedfirmware.org
Cc: linux-mm(a)kvack.org
Cc: Jens Wiklander <jens.wiklander@linaro.org>
Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>

---
Changes in v2:
- Al Viro: Avoid allocating the kiov.
- Sumit: Update cover letter to clarify the motivation behind removing
  get_kernel_pages()
- Link to v1: https://lore.kernel.org/r/20221002002326.946620-1-ira.weiny(a)intel.com

---
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            | 37 ++++++++++---------------------------
 include/linux/highmem-internal.h |  5 ++++-
 include/linux/mm.h               |  2 --
 mm/swap.c                        | 30 ------------------------------
 4 files changed, 14 insertions(+), 60 deletions(-)
---
base-commit: 0136d86b78522bbd5755f8194c97a987f0586ba5
change-id: 20230203-get_kernel_pages-199342cfba79

Best regards,
-- 
Ira Weiny <ira.weiny@intel.com>

Re: [PATCH v2 0/4] Remove get_kernel_pages()

[Linus Torvalds]

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On Fri, Feb 3, 2023 at 8:06 PM Ira Weiny <ira.weiny@intel.com> wrote:
>
> This series also fixes is_kmap_addr() and uses it to ensure no kmap addresses
> slip in later.

Ack. Please make it so.

That said...

I wasn't cc'd on all the patches, but checked them on the mailing
list, and that first is_kmap_addr() patch makes me a bit unhappy.

Right now that 'is_kmap_addr()' is only used for user copy addresses,
for debugging purposes, and I'm not exactly thrilled about extending
it this way.

I get the feeling that we should just have a name for that "kmap _or_
kmap_local" range instead of making it two ranges.

But admittedly I can't come up with anything better, and it looks like
different architectures may do different things.  I just don't like
it.

                Linus

Re: [PATCH v2 0/4] Remove get_kernel_pages()

[Sumit Garg]

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On Sat, 4 Feb 2023 at 09:36, Ira Weiny <ira.weiny@intel.com> wrote:
>
> Sumit,
>
> I did not see a follow up on this series per your last email.[1]  I'd like to
> move forward with getting rid of kmap_to_page().  So Hopefully this can land
> and you can build on this rather than the other way around?

Apologies Ira for keeping you waiting. Actually I was fully involved
with other high priority work with my upstream review backlog
increasing. So I wasn't able to devote time to this work. Sure I will
rebase my work on top of your changes.

-Sumit

>
> All,
>
> Al Viro found[2] that kmap_to_page() is broken.  But not only is it broken, it
> presents confusion over how highmem should be used because kmap() and friends
> should not be used for 'long term' mappings.
>
> get_kernel_pages() is a caller of kmap_to_page().  It only has one caller
> [shm_get_kernel_pages()] which does not need the functionality.
>
> 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 is_kmap_addr() and uses it to ensure no kmap addresses
> slip in later.
>
> [1] https://lore.kernel.org/all/CAFA6WYMqEVDVW-ifoh-V9ni1zntYdes8adQKf2XXAUpqdaW53w(a)mail.gmail.com/
> [2] https://lore.kernel.org/lkml/YzSSl1ItVlARDvG3(a)ZenIV
>
> To: Sumit Garg <sumit.garg@linaro.org>
> To: Andrew Morton <akpm@linux-foundation.org>
> Cc: "Al Viro" <viro@zeniv.linux.org.uk>
> Cc: "Christoph Hellwig" <hch@lst.de>
> Cc: linux-kernel(a)vger.kernel.org
> Cc: op-tee(a)lists.trustedfirmware.org
> Cc: linux-mm(a)kvack.org
> Cc: Jens Wiklander <jens.wiklander@linaro.org>
> Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
>
> ---
> Changes in v2:
> - Al Viro: Avoid allocating the kiov.
> - Sumit: Update cover letter to clarify the motivation behind removing
>   get_kernel_pages()
> - Link to v1: https://lore.kernel.org/r/20221002002326.946620-1-ira.weiny(a)intel.com
>
> ---
> 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            | 37 ++++++++++---------------------------
>  include/linux/highmem-internal.h |  5 ++++-
>  include/linux/mm.h               |  2 --
>  mm/swap.c                        | 30 ------------------------------
>  4 files changed, 14 insertions(+), 60 deletions(-)
> ---
> base-commit: 0136d86b78522bbd5755f8194c97a987f0586ba5
> change-id: 20230203-get_kernel_pages-199342cfba79
>
> Best regards,
> --
> Ira Weiny <ira.weiny@intel.com>