On 10/17/2022 8:20 PM, Christian König wrote:
Am 17.10.22 um 16:30 schrieb Arvind Yadav:
-This is purely a timing issue. Here, sometimes Job free is happening before the job is done. To fix this issue moving 'dma_fence_cb' callback from job(struct drm_sched_job) to scheduler fence (struct drm_sched_fence).
- Added drm_sched_fence_set_parent() function(and others *_parent_cb)
in sched_fence.c. Moved parent fence intilization and callback installation into this (this just cleanup).
BUG: kernel NULL pointer dereference, address: 0000000000000088 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 2 PID: 0 Comm: swapper/2 Not tainted 6.0.0-rc2-custom #1 Arvind : [dma_fence_default_wait _START] timeout = -1 Hardware name: AMD Dibbler/Dibbler, BIOS RDB1107CC 09/26/2018 RIP: 0010:drm_sched_job_done.isra.0+0x11/0x140 [gpu_sched] Code: 8b fe ff ff be 03 00 00 00 e8 7b da b7 e3 e9 d4 fe ff ff 66 0f 1f 44 00 00 0f 1f 44 00 00 55 48 89 e5 41 55 41 54 49 89 fc 53 <48> 8b 9f 88 00 00 00 f0 ff 8b f0 00 00 00 48 8b 83 80 01 00 00 f0 RSP: 0018:ffffb1b1801d4d38 EFLAGS: 00010087 RAX: ffffffffc0aa48b0 RBX: ffffb1b1801d4d70 RCX: 0000000000000018 RDX: 000036c70afb7c1d RSI: ffff8a45ca413c60 RDI: 0000000000000000 RBP: ffffb1b1801d4d50 R08: 00000000000000b5 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffffb1b1801d4d70 R14: ffff8a45c4160000 R15: ffff8a45c416a708 FS: 0000000000000000(0000) GS:ffff8a48a0a80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000088 CR3: 000000014ad50000 CR4: 00000000003506e0 Call Trace: <IRQ> drm_sched_job_done_cb+0x12/0x20 [gpu_sched] dma_fence_signal_timestamp_locked+0x7e/0x110 dma_fence_signal+0x31/0x60 amdgpu_fence_process+0xc4/0x140 [amdgpu] gfx_v9_0_eop_irq+0x9d/0xd0 [amdgpu] amdgpu_irq_dispatch+0xb7/0x210 [amdgpu] amdgpu_ih_process+0x86/0x100 [amdgpu] amdgpu_irq_handler+0x24/0x60 [amdgpu] __handle_irq_event_percpu+0x4b/0x190 handle_irq_event_percpu+0x15/0x50 handle_irq_event+0x39/0x60 handle_edge_irq+0xaf/0x210 __common_interrupt+0x6e/0x110 common_interrupt+0xc1/0xe0 </IRQ> <TASK>
Signed-off-by: Arvind Yadav Arvind.Yadav@amd.com
Changes in v2: Moving 'dma_fence_cb' callback from job(struct drm_sched_job) to scheduler fence(struct drm_sched_fence) instead of adding NULL check for s_fence.
Changes in v3: Added drm_sched_fence_set_parent() function(and others *_parent_cb) in sched_fence.c. Moved parent fence intilization and callback installation into this (this just cleanup).
drivers/gpu/drm/scheduler/sched_fence.c | 53 +++++++++++++++++++++++++ drivers/gpu/drm/scheduler/sched_main.c | 38 +++++------------- include/drm/gpu_scheduler.h | 12 +++++- 3 files changed, 72 insertions(+), 31 deletions(-)
diff --git a/drivers/gpu/drm/scheduler/sched_fence.c b/drivers/gpu/drm/scheduler/sched_fence.c index 7fd869520ef2..f6808f363261 100644 --- a/drivers/gpu/drm/scheduler/sched_fence.c +++ b/drivers/gpu/drm/scheduler/sched_fence.c @@ -77,6 +77,59 @@ static void drm_sched_fence_free_rcu(struct rcu_head *rcu) if (!WARN_ON_ONCE(!fence)) kmem_cache_free(sched_fence_slab, fence); }
Please add an empty line here.
I will fix in the next version of patch.
+/**
- drm_sched_job_done_cb - the callback for a done job
- @f: fence
- @cb: fence callbacks
- */
+static void drm_sched_job_done_cb(struct dma_fence *f, struct dma_fence_cb *cb)
Probably best to rename this to something like drm_sched_fence_parent_cb().
I will rename in the next version of patch.
+{ + struct drm_sched_fence *s_fence = container_of(cb, struct drm_sched_fence, + cb); + struct drm_gpu_scheduler *sched = s_fence->sched;
+ atomic_dec(&sched->hw_rq_count); + atomic_dec(sched->score);
+ dma_fence_get(&s_fence->finished);
We should probably make sure that this reference is taken before installing the callback.
Here, we are signaling the finished fence and dma_fence_signal is checking the reference.
So we do not need to check here.
+ drm_sched_fence_finished(s_fence); + dma_fence_put(&s_fence->finished); + wake_up_interruptible(&sched->wake_up_worker); +}
+int drm_sched_fence_add_parent_cb(struct dma_fence *fence, + struct drm_sched_fence *s_fence) +{ + return dma_fence_add_callback(fence, &s_fence->cb, + drm_sched_job_done_cb); +}
+bool drm_sched_fence_remove_parent_cb(struct drm_sched_fence *s_fence) +{ + return dma_fence_remove_callback(s_fence->parent, + &s_fence->cb); +}
Do we really need separate functions for that?
We can use 'drm_sched_fence_set_parent' but we need to add extra NULL check before
adding in the callback otherwise add-callback will throw the warning message every time.
If I add NULL check then will never get any callback warning message for setting NULL parent fence.
So I have kept separate functions.
+/**
- drm_sched_fence_set_parent - set the parent fence and add the
callback
- fence: pointer to the hw fence
- @s_fence: pointer to the fence
Reverse the parameter order, s_fence is the object we work on.
I will change order in next version of patch.
- Set the parent fence and intall the callback for a done job.
You need to document that we take the reference of the parent fence.
- */
+int drm_sched_fence_set_parent(struct dma_fence *fence, + struct drm_sched_fence *s_fence) +{ + if (s_fence->parent && + dma_fence_remove_callback(s_fence->parent, &s_fence->cb)) + dma_fence_put(s_fence->parent);
+ s_fence->parent = dma_fence_get(fence); + /* Drop for original kref_init of the fence */ + dma_fence_put(fence);
This leaks the reference to the old parent and the get/put dance is not optimal either.
Better do something like this.
/* We keep the reference of the parent fence here. */ swap(s_fence->parent, fence); dma_fence_put(fence);
I will change this in next version of patch.
+ return dma_fence_add_callback(fence, &s_fence->cb, + drm_sched_job_done_cb); +}
When installing the callback fails we usually call the callback function instead of returning the error.
I will call the drm_sched_job_done_cb(NULL, &s_fence->cb) callback.
/** * drm_sched_fence_free - free up an uninitialized fence diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c index 4cc59bae38dd..cfb52e15f5b0 100644 --- a/drivers/gpu/drm/scheduler/sched_main.c +++ b/drivers/gpu/drm/scheduler/sched_main.c @@ -253,13 +253,12 @@ drm_sched_rq_select_entity_fifo(struct drm_sched_rq *rq) /** * drm_sched_job_done - complete a job
- @s_job: pointer to the job which is done
- @s_fence: pointer to the fence of a done job
* * Finish the job's fence and wake up the worker thread. */ -static void drm_sched_job_done(struct drm_sched_job *s_job) +static void drm_sched_job_done(struct drm_sched_fence *s_fence) { - struct drm_sched_fence *s_fence = s_job->s_fence; struct drm_gpu_scheduler *sched = s_fence->sched; atomic_dec(&sched->hw_rq_count); @@ -273,18 +272,6 @@ static void drm_sched_job_done(struct drm_sched_job *s_job) wake_up_interruptible(&sched->wake_up_worker); } -/**
- drm_sched_job_done_cb - the callback for a done job
- @f: fence
- @cb: fence callbacks
- */
-static void drm_sched_job_done_cb(struct dma_fence *f, struct dma_fence_cb *cb) -{ - struct drm_sched_job *s_job = container_of(cb, struct drm_sched_job, cb);
- drm_sched_job_done(s_job); -}
/** * drm_sched_dependency_optimized - test if the dependency can be optimized * @@ -505,8 +492,7 @@ void drm_sched_stop(struct drm_gpu_scheduler *sched, struct drm_sched_job *bad) list_for_each_entry_safe_reverse(s_job, tmp, &sched->pending_list, list) { if (s_job->s_fence->parent &&
- dma_fence_remove_callback(s_job->s_fence->parent,
- &s_job->cb)) {
- drm_sched_fence_remove_parent_cb(s_job->s_fence)) {
dma_fence_put(s_job->s_fence->parent); s_job->s_fence->parent = NULL;
Better just call drm_sched_fence_set_parent() with NULL here to clear the currently installed parent.
This moves all this dance into the scheduler fence code.
atomic_dec(&sched->hw_rq_count); @@ -576,15 +562,14 @@ void drm_sched_start(struct drm_gpu_scheduler *sched, bool full_recovery) continue; if (fence) { - r = dma_fence_add_callback(fence, &s_job->cb, - drm_sched_job_done_cb); + r = drm_sched_fence_add_parent_cb(fence, s_job->s_fence); if (r == -ENOENT) - drm_sched_job_done(s_job); + drm_sched_job_done(s_job->s_fence); else if (r) DRM_DEV_ERROR(sched->dev, "fence add callback failed (%d)\n",
Completely nuke that here. All of this should be done in the single drm_sched_fence_set_parent() function.
And an error message is completely superfluous. We just need to handle the case that the callback can't be installed because the fence is already signaled.
I will do the changes as per your review comments, Thank you for the review.
Thanks,
~Arvind
Regards, Christian.
r); } else - drm_sched_job_done(s_job); + drm_sched_job_done(s_job->s_fence); } if (full_recovery) { @@ -1049,14 +1034,9 @@ static int drm_sched_main(void *param) drm_sched_fence_scheduled(s_fence); if (!IS_ERR_OR_NULL(fence)) { - s_fence->parent = dma_fence_get(fence); - /* Drop for original kref_init of the fence */ - dma_fence_put(fence);
- r = dma_fence_add_callback(fence, &sched_job->cb, - drm_sched_job_done_cb); + r = drm_sched_fence_set_parent(fence, s_fence); if (r == -ENOENT) - drm_sched_job_done(sched_job); + drm_sched_job_done(s_fence); else if (r) DRM_DEV_ERROR(sched->dev, "fence add callback failed (%d)\n", r); @@ -1064,7 +1044,7 @@ static int drm_sched_main(void *param) if (IS_ERR(fence)) dma_fence_set_error(&s_fence->finished, PTR_ERR(fence)); - drm_sched_job_done(sched_job); + drm_sched_job_done(s_fence); } wake_up(&sched->job_scheduled); diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h index 1f7d9dd1a444..7258e2fa195f 100644 --- a/include/drm/gpu_scheduler.h +++ b/include/drm/gpu_scheduler.h @@ -281,6 +281,10 @@ struct drm_sched_fence { * @owner: job owner for debugging */ void *owner; + /** + * @cb: callback + */ + struct dma_fence_cb cb; }; struct drm_sched_fence *to_drm_sched_fence(struct dma_fence *f); @@ -300,7 +304,6 @@ struct drm_sched_fence *to_drm_sched_fence(struct dma_fence *f); * be scheduled further. * @s_priority: the priority of the job. * @entity: the entity to which this job belongs.
- @cb: the callback for the parent fence in s_fence.
* * A job is created by the driver using drm_sched_job_init(), and * should call drm_sched_entity_push_job() once it wants the scheduler @@ -325,7 +328,6 @@ struct drm_sched_job { atomic_t karma; enum drm_sched_priority s_priority; struct drm_sched_entity *entity; - struct dma_fence_cb cb; /** * @dependencies: * @@ -559,6 +561,12 @@ void drm_sched_fence_free(struct drm_sched_fence *fence); void drm_sched_fence_scheduled(struct drm_sched_fence *fence); void drm_sched_fence_finished(struct drm_sched_fence *fence); +int drm_sched_fence_add_parent_cb(struct dma_fence *fence, + struct drm_sched_fence *s_fence); +bool drm_sched_fence_remove_parent_cb(struct drm_sched_fence *s_fence); +int drm_sched_fence_set_parent(struct dma_fence *fence, + struct drm_sched_fence *s_fence);
unsigned long drm_sched_suspend_timeout(struct drm_gpu_scheduler *sched); void drm_sched_resume_timeout(struct drm_gpu_scheduler *sched, unsigned long remaining);