[PATCH] drm/amdkfd: Fix kfd process ref leaking when userptr unmapping

[Philip Yang]

kfd_lookup_process_by_pid increases process ref, the refcount is
leaking.

Fixes: 7a566d7f56f4 ("amd/amdkfd: Trigger segfault for early userptr unmmapping")
Signed-off-by: Philip Yang <Philip.Yang at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
index 260165bbe373..99a32bc9bb89 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -2563,12 +2563,17 @@ static int update_invalid_user_pages(struct amdkfd_process_info *process_info,
 			 * from the KFD, trigger a segmentation fault in VM debug mode.
 			 */
 			if (amdgpu_ttm_adev(bo->tbo.bdev)->debug_vm_userptr) {
+				struct kfd_process *p;
+
 				pr_err("Pid %d unmapped memory before destroying userptr at GPU addr 0x%llx\n",
 								pid_nr(process_info->pid), mem->va);
 
 				// Send GPU VM fault to user space
-				kfd_signal_vm_fault_event_with_userptr(kfd_lookup_process_by_pid(process_info->pid),
-								mem->va);
+				p = kfd_lookup_process_by_pid(process_info->pid);
+				if (p) {
+					kfd_signal_vm_fault_event_with_userptr(p, mem->va);
+					kfd_unref_process(p);
+				}
 			}
 
 			ret = 0;
-- 
2.49.0