6.15-stable review patch. If anyone has any objections, please let me know.
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From: Matthew Auld matthew.auld@intel.com
commit 0ee54d5cacc0276ec631ac149825a24b59c51c38 upstream.
Customer is reporting a really subtle issue where we get random DMAR faults, hangs and other nasties for kernel migration jobs when stressing stuff like s2idle/s3/s4. The explosions seems to happen somewhere after resuming the system with splats looking something like:
PM: suspend exit rfkill: input handler disabled xe 0000:00:02.0: [drm] GT0: Engine reset: engine_class=bcs, logical_mask: 0x2, guc_id=0 xe 0000:00:02.0: [drm] GT0: Timedout job: seqno=24496, lrc_seqno=24496, guc_id=0, flags=0x13 in no process [-1] xe 0000:00:02.0: [drm] GT0: Kernel-submitted job timed out
The likely cause appears to be a race between suspend cancelling the worker that processes the free_job()'s, such that we still have pending jobs to be freed after the cancel. Following from this, on resume the pending_list will now contain at least one already complete job, but it looks like we call drm_sched_resubmit_jobs(), which will then call run_job() on everything still on the pending_list. But if the job was already complete, then all the resources tied to the job, like the bb itself, any memory that is being accessed, the iommu mappings etc. might be long gone since those are usually tied to the fence signalling.
This scenario can be seen in ftrace when running a slightly modified xe_pm IGT (kernel was only modified to inject artificial latency into free_job to make the race easier to hit):
xe_sched_job_run: dev=0000:00:02.0, fence=0xffff888276cc8540, seqno=0, lrc_seqno=0, gt=0, guc_id=0, batch_addr=0x000000146910 ... xe_exec_queue_stop: dev=0000:00:02.0, 3:0x2, gt=0, width=1, guc_id=0, guc_state=0x0, flags=0x13 xe_exec_queue_stop: dev=0000:00:02.0, 3:0x2, gt=0, width=1, guc_id=1, guc_state=0x0, flags=0x4 xe_exec_queue_stop: dev=0000:00:02.0, 4:0x1, gt=1, width=1, guc_id=0, guc_state=0x0, flags=0x3 xe_exec_queue_stop: dev=0000:00:02.0, 1:0x1, gt=1, width=1, guc_id=1, guc_state=0x0, flags=0x3 xe_exec_queue_stop: dev=0000:00:02.0, 4:0x1, gt=1, width=1, guc_id=2, guc_state=0x0, flags=0x3 xe_exec_queue_resubmit: dev=0000:00:02.0, 3:0x2, gt=0, width=1, guc_id=0, guc_state=0x0, flags=0x13 xe_sched_job_run: dev=0000:00:02.0, fence=0xffff888276cc8540, seqno=0, lrc_seqno=0, gt=0, guc_id=0, batch_addr=0x000000146910 ... ..... xe_exec_queue_memory_cat_error: dev=0000:00:02.0, 3:0x2, gt=0, width=1, guc_id=0, guc_state=0x3, flags=0x13
So the job_run() is clearly triggered twice for the same job, even though the first must have already signalled to completion during suspend. We can also see a CAT error after the re-submit.
To prevent this only resubmit jobs on the pending_list that have not yet signalled.
v2: - Make sure to re-arm the fence callbacks with sched_start(). v3 (Matt B): - Stop using drm_sched_resubmit_jobs(), which appears to be deprecated and just open-code a simple loop such that we skip calling run_job() on anything already signalled.
Link: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/4856 Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs") Signed-off-by: Matthew Auld matthew.auld@intel.com Cc: Thomas Hellström thomas.hellstrom@linux.intel.com Cc: Matthew Brost matthew.brost@intel.com Cc: William Tseng william.tseng@intel.com Cc: stable@vger.kernel.org # v6.8+ Reviewed-by: Matthew Brost matthew.brost@intel.com Reviewed-by: Tejas Upadhyay tejas.upadhyay@intel.com Link: https://lore.kernel.org/r/20250528113328.289392-2-matthew.auld@intel.com (cherry picked from commit 38fafa9f392f3110d2de431432d43f4eef99cd1b) Signed-off-by: Thomas Hellström thomas.hellstrom@linux.intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/xe/xe_gpu_scheduler.h | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
--- a/drivers/gpu/drm/xe/xe_gpu_scheduler.h +++ b/drivers/gpu/drm/xe/xe_gpu_scheduler.h @@ -51,7 +51,15 @@ static inline void xe_sched_tdr_queue_im
static inline void xe_sched_resubmit_jobs(struct xe_gpu_scheduler *sched) { - drm_sched_resubmit_jobs(&sched->base); + struct drm_sched_job *s_job; + + list_for_each_entry(s_job, &sched->base.pending_list, list) { + struct drm_sched_fence *s_fence = s_job->s_fence; + struct dma_fence *hw_fence = s_fence->parent; + + if (hw_fence && !dma_fence_is_signaled(hw_fence)) + sched->base.ops->run_job(s_job); + } }
static inline bool