From: Zhao Liu <zhao1.liu@xxxxxxxxx>
Hi list,
Sorry for a long delay since v1 [1]. This patchset is based on 197b6b6
(Linux 6.3-rc4).
Welcome and thanks for your review and comments!
# 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()[1]. 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 kamp_atomic()/kunmap_atomic() with
kmap_local_page()/kunmap_local() directly. With thses local
mappings, the page faults and preemption are allowed.
Patch 2 and 7 use memcpy_from_page() and memcpy_to_page() to replace
kamp_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 kamp_atomic()/kunmap_atomic() with kmap_local_page()/
kunmap_local() and also diable page fault since the for special
handling (pls see the commit message).
# 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.
# Reference
[1]: https://lore.kernel.org/lkml/20221017093726.2070674-1-zhao1.liu@xxxxxxxxxxxxxxx/
[1]: https://lore.kernel.org/all/20220813220034.806698-1-ira.weiny@xxxxxxxxx
---
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
