linux-kernel - Re: [PATCH v3 0/9] drm/i915: Replace kmap_atomic() with kmap_local

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Message-ID: <ZXsZeEw/w+LfaKyH@intel.com>
Date:   Thu, 14 Dec 2023 23:04:24 +0800
From:   Zhao Liu <zhao1.liu@...ux.intel.com>
To:     Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>
Cc:     Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Ira Weiny <ira.weiny@...el.com>,
        "Fabio M . De Francesco" <fmdefrancesco@...il.com>,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, Dave Hansen <dave.hansen@...el.com>,
        Zhenyu Wang <zhenyu.z.wang@...el.com>,
        Zhao Liu <zhao1.liu@...el.com>
Subject: Re: [PATCH v3 0/9] drm/i915: Replace kmap_atomic() with
 kmap_local_page()

On Thu, Dec 14, 2023 at 02:35:26PM +0000, Tvrtko Ursulin wrote:
> Date: Thu, 14 Dec 2023 14:35:26 +0000
> From: Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>
> Subject: Re: [PATCH v3 0/9] drm/i915: Replace kmap_atomic() with
>  kmap_local_page()
> 
> 
> On 14/12/2023 13:45, Tvrtko Ursulin wrote:
> > 
> > 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.
> 
> It all looks good to me. I only needed to queue a re-test in our CI since v3
> failed BAT, but pretty sure it wasn't at fault. Once I am satisfied with the
> results I will merge the series. Thanks for the cleanups and your patience!
> 
> Regards,
> 
> Tvrtko
> 

Thanks for your review!

Regards,
Zhao

> 
> > 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@...ux.intel.com>
> > > > 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@...el.com>
> > > > 
> > > > 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@linux.intel.com/
> > > > [2]:
> > > > https://lore.kernel.org/all/20220813220034.806698-1-ira.weiny@intel.com
> > > > 
> > > > 
> > > > 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
> > > >