Am 21.05.21 um 20:24 schrieb Felix Kuehling:
Am 2021-05-21 um 1:26 a.m. schrieb xinhui pan:
The reservation object might be locked again by evict/swap after
individualized. The race is like below.
cpu 0 cpu 1
BO release BO evict or swap
ttm_bo_individualize_resv {resv = &_resv}
ttm_bo_evict_swapout_allowable
dma_resv_trylock(resv)
->release_notify() {BUG_ON(!trylock(resv))}
if (!ttm_bo_get_unless_zero))
dma_resv_unlock(resv)
Actually this is not a bug if trylock fails. So use dma_resv_lock
instead.
Please test this with LOCKDEP enabled. I believe the trylock here was
needed to avoid potential deadlocks. Maybe Christian can fill in more
details.
Unfortunately I don't remember why trylock was needed here either.
But yes, testing with lockdep enabled is a really good idea.
Regards,
Christian.
Regards,
Felix
Signed-off-by: xinhui pan <xinhui.pan@xxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
index 928e8d57cd08..beacb46265f8 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -318,7 +318,7 @@ int amdgpu_amdkfd_remove_fence_on_pt_pd_bos(struct amdgpu_bo *bo)
ef = container_of(dma_fence_get(&info->eviction_fence->base),
struct amdgpu_amdkfd_fence, base);
- BUG_ON(!dma_resv_trylock(bo->tbo.base.resv));
+ dma_resv_lock(bo->tbo.base.resv, NULL);
ret = amdgpu_amdkfd_remove_eviction_fence(bo, ef);
dma_resv_unlock(bo->tbo.base.resv);
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