Re: [PATCH v3 0/9] drm/i915: Replace kmap_atomic() with kmap_local_page()

[Tvrtko Ursulin]

Hi Zhao,

On 14/12/2023 13:19, Zhao Liu wrote:
> Hi maintainers,
>
> Just kindly ping.
> May I ask if this refresh version could be merged into the next tree of
> the i915?

I certainly spotted your series last week or so but then it slipped my 
mind to go through it. Should be able to go through it today or tomorrow.

Regards,

Tvrtko

> Thanks,
> Zhao
>
> On Sun, Dec 03, 2023 at 09:29:38PM +0800, Zhao Liu wrote:
> > Date: Sun, 3 Dec 2023 21:29:38 +0800
> > From: Zhao Liu <zhao1.liu@xxxxxxxxxxxxxxx>
> > Subject: [PATCH v3 0/9] drm/i915: Replace kmap_atomic() with
> >   kmap_local_page()
> > X-Mailer: git-send-email 2.34.1
> >
> > From: Zhao Liu <zhao1.liu@xxxxxxxxx>
> >
> > Hi all,
> >
> > I refreshed this v3 by rebasing v2 [1] on the commit 968f35f4ab1c
> > ("Merge tag 'v6.7-rc3-smb3-client-fixes' of git://git.samba.org/sfrench/
> > cifs-2.6").
> >
> > Based on the current code, I rechecked the substitutions in v2 and they
> > still stand and are valid, so no code change in v3.
> >
> > Thanks for all the review! And sorry v2 was missed, I'll pay more
> > attention to this v3.
> >
> >
> > Purpose of This Patchset
> > ========================
> >
> > The purpose of this pacthset is to replace all uses of kmap_atomic() in
> > i915 with kmap_local_page() because the use of kmap_atomic() is being
> > deprecated in favor of kmap_local_page()[2]. And 92b64bd (mm/highmem:
> > add notes about conversions from kmap{,_atomic}()) has declared the
> > deprecation of kmap_atomic().
> >
> >
> > Motivation for Deprecating kmap_atomic() and Using kmap_local_page()
> > ====================================================================
> >
> > The main difference between atomic and local mappings is that local
> > mappings doesn't disable page faults or preemption (the preemption is
> > disabled for !PREEMPT_RT case, otherwise it only disables migration).
> >
> > With kmap_local_page(), we can avoid the often unwanted side effect of
> > unnecessary page faults and preemption disables.
> >
> >
> > Patch summary
> > =============
> >
> > Patch 1, 4-6 and 8-9 replace kmap_atomic()/kunmap_atomic() with
> >          kmap_local_page()/kunmap_local() directly. With these local
> >          mappings, the page faults and preemption are allowed.
> >
> > Patch 2 and 7 use memcpy_from_page() and memcpy_to_page() to replace
> >          kmap_atomic()/kunmap_atomic(). These two variants of memcpy()
> >          are based on the local mapping, so page faults and preemption
> >          are also allowed in these two interfaces.
> >
> > Patch 3 replaces kmap_atomic()/kunmap_atomic() with kmap_local_page()/
> >          kunmap_local() and also disable page fault since the for special
> >          handling (pls see the commit message).
> >
> >
> > Reference
> > =========
> >
> > [1]: https://lore.kernel.org/all/20230329073220.3982460-1-zhao1.liu@xxxxxxxxxxxxxxx/
> > [2]: https://lore.kernel.org/all/20220813220034.806698-1-ira.weiny@xxxxxxxxx
> >
> >
> > Thanks and Best Regards,
> > Zhao
> >
> > ---
> > Changlog:
> >
> > Changes since v2:
> > * Rebased on 968f35f4ab1c ("Merge tag 'v6.7-rc3-smb3-client-fixes' of
> >    git://git.samba.org/sfrench/cifs-2.6").
> > * Removed changelog (of v2) in commit message.
> > * Fixed typo in cover letter (Fabio).
> > * Added Reviewed-by tags from Ira and Fabio.
> >
> > Changes since v1:
> > * Dropped hot plug related description in commit message since it has
> >    nothing to do with kmap_local_page().
> > * Emphasized the motivation for using kmap_local_page() in commit
> >    message.
> > * Rebased patch 1 on f47e630 (drm/i915/gem: Typecheck page lookups) to
> >    keep the "idx" variable of type pgoff_t here.
> > * Used memcpy_from_page() and memcpy_to_page() to replace
> >    kmap_local_page() + memcpy() in patch 2.
> >
> > ---
> > Zhao Liu (9):
> >    drm/i915: Use kmap_local_page() in gem/i915_gem_object.c
> >    drm/i915: Use memcpy_[from/to]_page() in gem/i915_gem_pyhs.c
> >    drm/i915: Use kmap_local_page() in gem/i915_gem_shmem.c
> >    drm/i915: Use kmap_local_page() in gem/selftests/huge_pages.c
> >    drm/i915: Use kmap_local_page() in gem/selftests/i915_gem_coherency.c
> >    drm/i915: Use kmap_local_page() in gem/selftests/i915_gem_context.c
> >    drm/i915: Use memcpy_from_page() in gt/uc/intel_uc_fw.c
> >    drm/i915: Use kmap_local_page() in i915_cmd_parser.c
> >    drm/i915: Use kmap_local_page() in gem/i915_gem_execbuffer.c
> >
> >   drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c       | 10 +++++-----
> >   drivers/gpu/drm/i915/gem/i915_gem_object.c           |  8 +++-----
> >   drivers/gpu/drm/i915/gem/i915_gem_phys.c             | 10 ++--------
> >   drivers/gpu/drm/i915/gem/i915_gem_shmem.c            |  6 ++++--
> >   drivers/gpu/drm/i915/gem/selftests/huge_pages.c      |  6 +++---
> >   .../gpu/drm/i915/gem/selftests/i915_gem_coherency.c  | 12 ++++--------
> >   .../gpu/drm/i915/gem/selftests/i915_gem_context.c    |  8 ++++----
> >   drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c             |  5 +----
> >   drivers/gpu/drm/i915/i915_cmd_parser.c               |  4 ++--
> >   9 files changed, 28 insertions(+), 41 deletions(-)
> >
> > --
> > 2.34.1