commit 6ab3d4353b upstream.
The connector type for the DataImage SCF0700C48GGU18 panel is missing and
devm_drm_panel_bridge_add() requires connector type to be set. This leads
to a warning and a backtrace in the kernel log and panel does not work:
"
WARNING: CPU: 3 PID: 38 at drivers/gpu/drm/bridge/panel.c:379 devm_drm_of_get_bridge+0xac/0xb8
"
The warning is triggered by a check for valid connector type in
devm_drm_panel_bridge_add(). If there is no valid connector type
set for a panel, the warning is printed and panel is not added.
Fill in the missing connector type to fix the warning and make
the panel operational once again.
Cc: stable@vger.kernel.org
Fixes: 97ceb1fb08 ("drm/panel: simple: Add support for DataImage SCF0700C48GGU18")
Signed-off-by: Marek Vasut <marex@nabladev.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patch.msgid.link/20260110152750.73848-1-marex@nabladev.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 9e9bc6be0f upstream.
For a while, I've been seeing a strange issue where some (usually not all)
of the display DMA channels will suddenly hang, particularly when there is
a visible cursor on the screen that is being frequently updated, and
especially when said cursor happens to go between two screens. While this
brings back lovely memories of fixing Intel Skylake bugs, I would quite
like to fix it :).
It turns out the problem that's happening here is that we're managing to
reach nv50_head_flush_set() in our atomic commit path without actually
holding nv50_disp->mutex. This means that cursor updates happening in
parallel (along with any other atomic updates that need to use the core
channel) will race with eachother, which eventually causes us to corrupt
the pushbuffer - leading to a plethora of various GSP errors, usually:
nouveau 0000:c1:00.0: gsp: Xid:56 CMDre 00000000 00000218 00102680 00000004 00800003
nouveau 0000:c1:00.0: gsp: Xid:56 CMDre 00000000 0000021c 00040509 00000004 00000001
nouveau 0000:c1:00.0: gsp: Xid:56 CMDre 00000000 00000000 00000000 00000001 00000001
The reason this is happening is because generally we check whether we need
to set nv50_atom->lock_core at the end of nv50_head_atomic_check().
However, curs507a_prepare is called from the fb_prepare callback, which
happens after the atomic check phase. As a result, this can lead to commits
that both touch the core channel but also don't grab nv50_disp->mutex.
So, fix this by making sure that we set nv50_atom->lock_core in
cus507a_prepare().
Reviewed-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Fixes: 1590700d94 ("drm/nouveau/kms/nv50-: split each resource type into their own source files")
Cc: <stable@vger.kernel.org> # v4.18+
Link: https://patch.msgid.link/20251219215344.170852-2-lyude@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 80614c5098 upstream.
If dqm->ops.initialize() fails, add deallocate_hiq_sdma_mqd()
to release the memory allocated by allocate_hiq_sdma_mqd().
Move deallocate_hiq_sdma_mqd() up to ensure proper function
visibility at the point of use.
Fixes: 11614c36bc ("drm/amdkfd: Allocate MQD trunk for HIQ and SDMA")
Signed-off-by: Haoxiang Li <lihaoxiang@isrc.iscas.ac.cn>
Signed-off-by: Felix Kuehling <felix.kuehling@amd.com>
Reviewed-by: Oak Zeng <Oak.Zeng@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit b7cccc8286bb9919a0952c812872da1dcfe9d390)
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 28695ca09d upstream.
When an eGPU is unplugged the KFD topology should also be destroyed
for that GPU. This never happens because the fini_sw callbacks never
get to run. Run them manually before calling amdgpu_device_ip_fini_early()
when a device has already been disconnected.
This location is intentionally chosen to make sure that the kfd locking
refcount doesn't get incremented unintentionally.
Cc: kent.russell@amd.com
Closes: https://community.frame.work/t/amd-egpu-on-linux/8691/33
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
Reviewed-by: Kent Russell <kent.russell@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 6a23e7b4332c10f8b56c33a9c5431b52ecff9aab)
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit a8d42cd228 upstream.
When compiling allmodconfig (CONFIG_WERROR=y) with clang-19, see the
following errors:
.../display/dc/dml2/display_mode_core.c:6268:13: warning: stack frame size (3128) exceeds limit (3072) in 'dml_prefetch_check' [-Wframe-larger-than]
.../display/dc/dml2/dml21/src/dml2_core/dml2_core_dcn4_calcs.c:7236:13: warning: stack frame size (3256) exceeds limit (3072) in 'dml_core_mode_support' [-Wframe-larger-than]
Mark static functions called by dml_prefetch_check() and
dml_core_mode_support() noinline_for_stack to avoid them become huge
functions and thus exceed the frame size limit.
A way to reproduce:
$ git checkout next-20250107
$ mkdir build_dir
$ export PATH=/tmp/llvm-19.1.6-x86_64/bin:$PATH
$ make LLVM=1 O=build_dir allmodconfig
$ make LLVM=1 O=build_dir drivers/gpu/drm/ -j
The way how it chose static functions to mark:
[0] Unset CONFIG_WERROR in build_dir/.config.
To get display_mode_core.o without errors.
[1] Get a function list called by dml_prefetch_check().
$ sed -n '6268,6711p' drivers/gpu/drm/amd/display/dc/dml2/display_mode_core.c \
| sed -n -r 's/.*\W(\w+)\(.*/\1/p' | sort -u >/tmp/syms
[2] Get the non-inline function list.
Objdump won't show the symbols if they are inline functions.
$ make LLVM=1 O=build_dir drivers/gpu/drm/ -j
$ objdump -d build_dir/.../display_mode_core.o | \
./scripts/checkstack.pl x86_64 0 | \
grep -f /tmp/syms | cut -d' ' -f2- >/tmp/orig
[3] Get the full function list.
Append "-fno-inline" to `CFLAGS_.../display_mode_core.o` in
drivers/gpu/drm/amd/display/dc/dml2/Makefile.
$ make LLVM=1 O=build_dir drivers/gpu/drm/ -j
$ objdump -d build_dir/.../display_mode_core.o | \
./scripts/checkstack.pl x86_64 0 | \
grep -f /tmp/syms | cut -d' ' -f2- >/tmp/noinline
[4] Get the inline function list.
If a symbol only in /tmp/noinline but not in /tmp/orig, it is a good
candidate to mark noinline.
$ diff /tmp/orig /tmp/noinline
Chosen functions and their stack sizes:
CalculateBandwidthAvailableForImmediateFlip [display_mode_core.o]:144
CalculateExtraLatency [display_mode_core.o]:176
CalculateTWait [display_mode_core.o]:64
CalculateVActiveBandwithSupport [display_mode_core.o]:112
set_calculate_prefetch_schedule_params [display_mode_core.o]:48
CheckGlobalPrefetchAdmissibility [dml2_core_dcn4_calcs.o]:544
calculate_bandwidth_available [dml2_core_dcn4_calcs.o]:320
calculate_vactive_det_fill_latency [dml2_core_dcn4_calcs.o]:272
CalculateDCFCLKDeepSleep [dml2_core_dcn4_calcs.o]:208
CalculateODMMode [dml2_core_dcn4_calcs.o]:208
CalculateOutputLink [dml2_core_dcn4_calcs.o]:176
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
[nathan: Fix conflicts in dml2_core_dcn4_calcs.c]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 969faea4e9 ]
Pass character "0" rather than NULL terminator to properly format
queue restoration SMI events. Currently, the NULL terminator precedes
the newline character that is intended to delineate separate events
in the SMI event buffer, which can break userspace parsers.
Signed-off-by: Brian Kocoloski <brian.kocoloski@amd.com>
Reviewed-by: Philip Yang <Philip.Yang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 6e7143e5e6e21f9d5572e0390f7089e6d53edf3c)
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 7074045437 ]
After an innocuous optimization change in clang-22, allmodconfig (which
enables CONFIG_KASAN and CONFIG_WERROR) breaks with:
drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn32/display_mode_vba_32.c:1724:6: error: stack frame size (3144) exceeds limit (3072) in 'dml32_ModeSupportAndSystemConfigurationFull' [-Werror,-Wframe-larger-than]
1724 | void dml32_ModeSupportAndSystemConfigurationFull(struct display_mode_lib *mode_lib)
| ^
With clang-21, this function was already pretty close to the existing
limit of 3072 bytes.
drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn32/display_mode_vba_32.c:1724:6: error: stack frame size (2904) exceeds limit (2048) in 'dml32_ModeSupportAndSystemConfigurationFull' [-Werror,-Wframe-larger-than]
1724 | void dml32_ModeSupportAndSystemConfigurationFull(struct display_mode_lib *mode_lib)
| ^
A similar situation occurred in dml2, which was resolved by
commit e4479aecf6 ("drm/amd/display: Increase sanitizer frame larger
than limit when compile testing with clang") by increasing the limit for
clang when compile testing with certain sanitizer enabled, so that
allmodconfig (an easy testing target) continues to work.
Apply that same change to the dml folder to clear up the warning for
allmodconfig, unbreaking the build.
Closes: https://github.com/ClangBuiltLinux/linux/issues/2135
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 25314b453cf812150e9951a32007a32bba85707e)
Cc: stable@vger.kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 820ccf8cb2 ]
Currently, there are several files in drm/amd/display that aim to have a
higher -Wframe-larger-than value to avoid instances of that warning with
a lower value from the user's configuration. However, with the way that
it is currently implemented, it does not respect the user's request via
CONFIG_FRAME_WARN for a higher stack frame limit, which can cause pain
when new instances of the warning appear and break the build due to
CONFIG_WERROR.
Adjust the logic to switch from a hard coded -Wframe-larger-than value
to only using the value as a minimum clamp and deferring to the
requested value from CONFIG_FRAME_WARN if it is higher.
Suggested-by: Harry Wentland <harry.wentland@amd.com>
Reported-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Closes: https://lore.kernel.org/2025013003-audience-opposing-7f95@gregkh/
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Stable-dep-of: 7074045437 ("drm/amd/display: Apply e4479aecf6 to dml")
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 7329417fc9 ]
On a 32-bit ARM system, the audio_decoder struct ends up being too large
for dp_retrain_link_dp_test.
link_dp_cts.c:157:1: error: the frame size of 1328 bytes is larger than
1280 bytes [-Werror=frame-larger-than=]
This is mitigated by shrinking the members of the struct and avoids
having to deal with dynamic allocation.
feed_back_divider is assigned but otherwise unused. Remove both.
pixel_repetition looks like it should be a bool since it's only ever
assigned to 1. But there are checks for 2 and 4. Reduce to uint8_t.
Remove ss_percentage_divider. Unused.
Shrink refresh_rate as it gets assigned to at most a 3 digit integer
value.
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 3849efdc7888d537f09c3dcfaea4b3cd377a102e)
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 8defb4f081 ]
Otherwise userspace may be fooled into believing it has a reserved VMID
when in reality it doesn't, ultimately leading to GPU hangs when SPM is
used.
Fixes: 80e709ee6e ("drm/amdgpu: add option params to enforce process isolation between graphics and compute")
Cc: stable@vger.kernel.org
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Natalie Vock <natalie.vock@gmx.de>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
[ adapted 3-argument amdgpu_vmid_alloc_reserved(adev, vm, vmhub) call to 2-argument version and added separate error check to preserve reserved_vmid tracking logic. ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 560271e10b upstream.
Since we recently started warning about uses of this function after the
atomic check phase completes, we've started getting warnings about this in
nouveau. It appears a misplaced drm_atomic_get_crtc_state() call has been
hiding in our .prepare_fb callback for a while.
So, fix this by adding a new nv50_head_atom_get_new() function and use that
in our .prepare_fb callback instead.
Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Fixes: 1590700d94 ("drm/nouveau/kms/nv50-: split each resource type into their own source files")
Cc: <stable@vger.kernel.org> # v4.18+
Link: https://patch.msgid.link/20251211190256.396742-1-lyude@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 4fe2bd1954 upstream.
Initialize the eb.vma array with values of 0 when the eb structure is
first set up. In particular, this sets the eb->vma[i].vma pointers to
NULL, simplifying cleanup and getting rid of the bug described below.
During the execution of eb_lookup_vmas(), the eb->vma array is
successively filled up with struct eb_vma objects. This process includes
calling eb_add_vma(), which might fail; however, even in the event of
failure, eb->vma[i].vma is set for the currently processed buffer.
If eb_add_vma() fails, eb_lookup_vmas() returns with an error, which
prompts a call to eb_release_vmas() to clean up the mess. Since
eb_lookup_vmas() might fail during processing any (possibly not first)
buffer, eb_release_vmas() checks whether a buffer's vma is NULL to know
at what point did the lookup function fail.
In eb_lookup_vmas(), eb->vma[i].vma is set to NULL if either the helper
function eb_lookup_vma() or eb_validate_vma() fails. eb->vma[i+1].vma is
set to NULL in case i915_gem_object_userptr_submit_init() fails; the
current one needs to be cleaned up by eb_release_vmas() at this point,
so the next one is set. If eb_add_vma() fails, neither the current nor
the next vma is set to NULL, which is a source of a NULL deref bug
described in the issue linked in the Closes tag.
When entering eb_lookup_vmas(), the vma pointers are set to the slab
poison value, instead of NULL. This doesn't matter for the actual
lookup, since it gets overwritten anyway, however the eb_release_vmas()
function only recognizes NULL as the stopping value, hence the pointers
are being set to NULL as they go in case of intermediate failure. This
patch changes the approach to filling them all with NULL at the start
instead, rather than handling that manually during failure.
Reported-by: Gangmin Kim <km.kim1503@gmail.com>
Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/15062
Fixes: 544460c338 ("drm/i915: Multi-BB execbuf")
Cc: stable@vger.kernel.org # 5.16.x
Signed-off-by: Krzysztof Niemiec <krzysztof.niemiec@intel.com>
Reviewed-by: Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>
Reviewed-by: Krzysztof Karas <krzysztof.karas@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20251216180900.54294-2-krzysztof.niemiec@intel.com
(cherry picked from commit 08889b706d4f0b8d2352b7ca29c2d8df4d0787cd)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit fe3ccd2413 upstream.
When imported dma-bufs are destroyed, TTM is not fully
individualizing the dma-resv, but it *is* copying the fences that
need to be waited for before declaring idle. So in the case where
the bo->resv != bo->_resv we can still drop the preempt-fences, but
make sure we do that on bo->_resv which contains the fence-pointer
copy.
In the case where the copying fails, bo->_resv will typically not
contain any fences pointers at all, so there will be nothing to
drop. In that case, TTM would have ensured all fences that would
have been copied are signaled, including any remaining preempt
fences.
Fixes: dd08ebf6c3 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Fixes: fa0af721bd ("drm/ttm: test private resv obj on release/destroy")
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: <stable@vger.kernel.org> # v6.16+
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Tested-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patch.msgid.link/20251217093441.5073-1-thomas.hellstrom@linux.intel.com
(cherry picked from commit 425fe550fb513b567bd6d01f397d274092a9c274)
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 6f0f404bd2 upstream.
A 10ms timeslice for long-running workloads is far too long and causes
significant jitter in benchmarks when the system is shared. Adjust the
value to 5ms for preempt-fencing VMs, as the resume step there is quite
costly as memory is moved around, and set it to zero for pagefault VMs,
since switching back to pagefault mode after dma-fence mode is
relatively fast.
Also change min_run_period_ms to 'unsiged int' type rather than 's64' as
only positive values make sense.
Fixes: dd08ebf6c3 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Cc: stable@vger.kernel.org
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patch.msgid.link/20251212182847.1683222-2-matthew.brost@intel.com
(cherry picked from commit 33a5abd9a68394aa67f9618b20eee65ee8702ff4)
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 1c7f9e528f upstream.
GCC notices that the 16-byte uabi_name field could theoretically be too
small for the formatted string if the instance number exceeds 100.
So grow the field to 20 bytes.
drivers/gpu/drm/i915/intel_memory_region.c: In function ‘intel_memory_region_create’:
drivers/gpu/drm/i915/intel_memory_region.c:273:61: error: ‘%u’ directive output may be truncated writing between 1 and 5 bytes into a region of size between 3 and 11 [-Werror=format-truncation=]
273 | snprintf(mem->uabi_name, sizeof(mem->uabi_name), "%s%u",
| ^~
drivers/gpu/drm/i915/intel_memory_region.c:273:58: note: directive argument in the range [0, 65535]
273 | snprintf(mem->uabi_name, sizeof(mem->uabi_name), "%s%u",
| ^~~~~~
drivers/gpu/drm/i915/intel_memory_region.c:273:9: note: ‘snprintf’ output between 7 and 19 bytes into a destination of size 16
273 | snprintf(mem->uabi_name, sizeof(mem->uabi_name), "%s%u",
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
274 | intel_memory_type_str(type), instance);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Fixes: 3b38d35157 ("drm/i915: Add stable memory region names")
Cc: <stable@vger.kernel.org> # v6.8+
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Tvrtko Ursulin <tursulin@ursulin.net>
Link: https://lore.kernel.org/r/20251205113500.684286-2-ardb@kernel.org
(cherry picked from commit 18476087f1a18dc279d200d934ad94fba1fb51d5)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit b7851f8c66 upstream.
The trap may be entered with dependency checking disabled.
Wait for dependency counters and save/restore scheduling mode.
v2:
Use ttmp1 instead of ttmp11. ttmp11 is not zero-initialized.
While the trap handler does zero this field before use, a user-mode
second-level trap handler could not rely on this being zero when
using an older kernel mode driver.
v3:
Use ttmp11 primarily but copy to ttmp1 before jumping to the
second level trap handler. ttmp1 is inspectable by a debugger.
Unexpected bits in the unused space may regress existing software.
Signed-off-by: Jay Cornwall <jay.cornwall@amd.com>
Reviewed-by: Lancelot Six <lancelot.six@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 423888879412e94725ca2bdccd89414887d98e31)
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit d4cd665c98 upstream.
Maintain two separate RB trees per order - one for clear (zeroed) blocks
and another for dirty (uncleared) blocks. This separation improves
code clarity and makes it more obvious which tree is being searched
during allocation. It also improves scalability and efficiency when
searching for a specific type of block, avoiding unnecessary checks
and making the allocator more predictable under fragmentation.
The changes have been validated using the existing drm_buddy_test
KUnit test cases, along with selected graphics workloads,
to ensure correctness and avoid regressions.
v2: Missed adding the suggested-by tag. Added it in v2.
v3(Matthew):
- Remove the double underscores from the internal functions.
- Rename the internal functions to have less generic names.
- Fix the error handling code.
- Pass tree argument for the tree macro.
- Use the existing dirty/free bit instead of new tree field.
- Make free_trees[] instead of clear_tree and dirty_tree for
more cleaner approach.
v4:
- A bug was reported by Intel CI and it is fixed by
Matthew Auld.
- Replace the get_root function with
&mm->free_trees[tree][order] (Matthew)
- Remove the unnecessary rbtree_is_empty() check (Matthew)
- Remove the unnecessary get_tree_for_flags() function.
- Rename get_tree_for_block() name with get_block_tree() for more
clarity.
v5(Jani Nikula):
- Don't use static inline in .c files.
- enum free_tree and enumerator names are quite generic for a header
and usage and the whole enum should be an implementation detail.
v6:
- Rewrite the __force_merge() function using the rb_last() and rb_prev().
v7(Matthew):
- Replace the open-coded tree iteration for loops with the
for_each_free_tree() macro throughout the code.
- Fixed out_free_roots to prevent double decrement of i,
addressing potential crash.
- Replaced enum drm_buddy_free_tree with unsigned int
in for_each_free_tree loops.
Cc: stable@vger.kernel.org
Fixes: a68c7eaa7a ("drm/amdgpu: Enable clear page functionality")
Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com>
Suggested-by: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4260
Link: https://lore.kernel.org/r/20251006095124.1663-2-Arunpravin.PaneerSelvam@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit c178e534ff upstream.
Replace the freelist (O(n)) used for free block management with a
red-black tree, providing more efficient O(log n) search, insert,
and delete operations. This improves scalability and performance
when managing large numbers of free blocks per order (e.g., hundreds
or thousands).
In the VK-CTS memory stress subtest, the buddy manager merges
fragmented memory and inserts freed blocks into the freelist. Since
freelist insertion is O(n), this becomes a bottleneck as fragmentation
increases. Benchmarking shows list_insert_sorted() consumes ~52.69% CPU
with the freelist, compared to just 0.03% with the RB tree
(rbtree_insert.isra.0), despite performing the same sorted insert.
This also improves performance in heavily fragmented workloads,
such as games or graphics tests that stress memory.
As the buddy allocator evolves with new features such as clear-page
tracking, the resulting fragmentation and complexity have grown.
These RB-tree based design changes are introduced to address that
growth and ensure the allocator continues to perform efficiently
under fragmented conditions.
The RB tree implementation with separate clear/dirty trees provides:
- O(n log n) aggregate complexity for all operations instead of O(n^2)
- Elimination of soft lockups and system instability
- Improved code maintainability and clarity
- Better scalability for large memory systems
- Predictable performance under fragmentation
v3(Matthew):
- Remove RB_EMPTY_NODE check in force_merge function.
- Rename rb for loop macros to have less generic names and move to
.c file.
- Make the rb node rb and link field as union.
v4(Jani Nikula):
- The kernel-doc comment should be "/**"
- Move all the rbtree macros to rbtree.h and add parens to ensure
correct precedence.
v5:
- Remove the inline in a .c file (Jani Nikula).
v6(Peter Zijlstra):
- Add rb_add() function replacing the existing rbtree_insert() code.
v7:
- A full walk iteration in rbtree is slower than the list (Peter Zijlstra).
- The existing rbtree_postorder_for_each_entry_safe macro should be used
in scenarios where traversal order is not a critical factor (Christian).
v8(Matthew):
- Remove the rbtree_is_empty() check in this patch as well.
Cc: stable@vger.kernel.org
Fixes: a68c7eaa7a ("drm/amdgpu: Enable clear page functionality")
Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://lore.kernel.org/r/20251006095124.1663-1-Arunpravin.PaneerSelvam@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
