Re: [REGRESSION] drm/amdkfd: SVM split-tail remap regression causes SDMA0 permission fault on RX 7600 XT

I cannot compile kfd_svm_split_hsa_copy.c, there is no 
"trace_history_replay.inc".

Or can you  send the test binary?  That should be enough to triage the 
issue since it is a regression as you mentioned.

Regards

Xiaogang

On 6/2/2026 5:04 AM, Gerhard Schwanzer wrote:
> Hi,
>
> I would like to make sure this AMDKFD SVM regression is tracked by the
> Linux regression process.
>
> GitLab report:
>
>   https://gitlab.freedesktop.org/drm/amd/-/work_items/4914
>
> The regression was originally reported on 2026-01-27. It was bisected 
> to the
> same functional change that Alex Deucher's revert patch later targeted:
>
>   448ee45353ef9fb1a34f5f26eb3f48923c6f0898
>   drm/amdkfd: Use huge page size to check split svm range alignment
>
> The affected kernel line I tested identifies the same change as:
>
>   bf2084a7b1d75d093b6a79df4c10142d49fbaa0e
>
> Alex's revert patch:
>
> https://lists.freedesktop.org/archives/amd-gfx/2026-February/138824.html
>
> A small C/HSA reproducer is now available in the GitLab report. It 
> does not
> require PyTorch, ComfyUI, Docker, model files, or the original 
> workload. It
> uses ROCr/HSA, an anonymous THP-advised host mapping, explicit KFD SVM
> SET_ATTR ioctls, and an HSA SDMA D2H copy.
>
> Single reproducer command, same binary on both kernels:
>
>   ./kfd_svm_split_hsa_copy --upstream-ab
>
> Same-machine A/B result on an RX 7600 XT:
>
>   448ee453/bf2084a7 active:
>     1/1 run faults with SDMA0 permission fault
>     GCVM_L2_PROTECTION_FAULT_STATUS=0x00841A51
>
>   448ee453/bf2084a7 locally reverted:
>     10/10 runs complete
>     no ROCr memory access fault
>     no new GCVM/SDMA0 permission fault in dmesg
>
> The bad fault page is inside the split tail and inside the SDMA copy 
> range:
>
>   critical tail: [0x722429d61..0x722429dff]
>   copy pages:    [0x722429b30..0x722429d70]
>   fault page:    0x722429d65
>
> A full ftrace/PTE run with the same C reproducer/SVM sequence also shows:
>
>   split_tail ... current_remap=0 old_remap=1 missed=1
>   MISSED_REMAP_CANDIDATE split=tail
>   no amdgpu_vm_update_ptes covering the fault page after the marker 
> before
>   the fault-side GET_ATTR
>
> The suspected code issue is that the split-tail/head remap predicate 
> introduced
> by 448ee453/bf2084a7 can miss tails inside the final 512-page block. 
> Since
> prange->last is inclusive, ALIGN_DOWN(prange->last, 512) is the start 
> of the
> final block, not an exclusive upper bound.
>
> I also sent a short follow-up to amd-gfx with the reproducer/A-B 
> summary and
> asked what original failure or workload 448ee453/bf2084a7 was intended 
> to fix:
>
> https://lists.freedesktop.org/archives/amd-gfx/2026-June/145800.html
>
> I can resend the reproducer source and summaries directly on-list if 
> preferred.
>
> #regzbot introduced: 448ee45353ef9fb1a34f5f26eb3f48923c6f0898
> #regzbot monitor: 
> https://gitlab.freedesktop.org/drm/amd/-/work_items/4914
>
> Thanks,
> Gerhard Schwanzer