drm/amdkfd: disable debug before retiring MES process context on teardown

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On process teardown, kfd_process_notifier_release_internal() called
kfd_process_dequeue_from_all_devices() (which issues the MES
SET_SHADER_DEBUGGER process_ctx_flush=1 that retires the process context)
before kfd_dbg_trap_disable(). For a process under a debugger, the debug
teardown path (kfd_dbg_trap_disable -> kfd_dbg_trap_deactivate) then issues
several SET_SHADER_DEBUGGER process_ctx_flush=0 packets (reset wave launch
mode, clear debug flags, reset MES debug mode). Because those packets carry
the process_context_addr, MES re-adds the process to its scheduler list
after the flush had retired it.

Teardown then frees proc_ctx_bo, and a later MES scheduling pass dereferences
the freed process context, producing a GPUVM page fault (vmid 0, GC_UTCL2)
on the freed page. This is intermittent because it depends on an MES pass
landing on the process before its GART page is reused. It is specific to the
debugger path, where queues are added with skip_process_ctx_clear=1 so the
last REMOVE_QUEUE does not clear the context and delisting relies on the
flush.

Reorder teardown so debug is disabled first, and the process context is
flushed/retired last, so nothing re-adds the process after it is retired.
kfd_dbg_trap_disable() now runs while queues still exist, which matches the
normal live debug-disable ordering.

Signed-off-by: Alex Sierra <alex.sierra@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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Alex Sierra 2026-07-24 15:53:48 -05:00 • committed by Alex Deucher

parent f8497de171

commit 95263281fd

1 changed files with 28 additions and 16 deletions

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drivers/gpu/drm/amd/amdkfd/kfd_process.c

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