Re: [PATCH 4/7] drm/amd: kill the outdated "Only the pthreads threading model is supported" checks

On 12/08, Christian König wrote:

On 12/7/25 13:39, Oleg Nesterov wrote:

quoted

Nowaday task->group_leader->mm != task->mm is only possible if
a) task is not a group leader and b) task->group_leader->mm == NULL
because task->group_leader has already exited using sys_exit().

Just for my understanding: That is because CLONE_THREAD can only be
specified together with CLONE_SIGHAND and CLONE_VM, correct?

Yes, copy copy_process() does

	if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
		return ERR_PTR(-EINVAL);

	if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
		return ERR_PTR(-EINVAL);

	...

	if (clone_flags & CLONE_THREAD) {
		p->group_leader = current->group_leader;
		p->tgid = current->tgid;
	} else {
		p->group_leader = p;
		p->tgid = p->pid;
	}

Reviewed-by: Christian König <christian.koenig@amd.com>

Thanks!

Should we pick that one up or do you want to merge it upstream somehow?

If you don't object, I would like to route this series via -mm tree.

See 0/7, I am going to send more (simple) tree-wide changes which depend
on this series.

Oleg.

Regards,
Christian.

quoted

---
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c   |  3 ---
 drivers/gpu/drm/amd/amdkfd/kfd_process.c | 10 ----------
 2 files changed, 13 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index a0f8ba382b9e..e44f158a11f0 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c

@@ -2551,9 +2551,6 @@ void amdgpu_vm_set_task_info(struct amdgpu_vm *vm)
 	vm->task_info->task.pid = current->pid;
 	get_task_comm(vm->task_info->task.comm, current);

-	if (current->group_leader->mm != current->mm)
-		return;
-
 	vm->task_info->tgid = current->tgid;
 	get_task_comm(vm->task_info->process_name, current->group_leader);
 }

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
index a085faac9fe1..f8ef18a3aa71 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c

@@ -833,12 +833,6 @@ struct kfd_process *kfd_create_process(struct task_struct *thread)
 	if (!(thread->mm && mmget_not_zero(thread->mm)))
 		return ERR_PTR(-EINVAL);

-	/* Only the pthreads threading model is supported. */
-	if (thread->group_leader->mm != thread->mm) {
-		mmput(thread->mm);
-		return ERR_PTR(-EINVAL);
-	}
-
 	/* If the process just called exec(3), it is possible that the
 	 * cleanup of the kfd_process (following the release of the mm
 	 * of the old process image) is still in the cleanup work queue.

@@ -918,10 +912,6 @@ struct kfd_process *kfd_get_process(const struct task_struct *thread)
 	if (!thread->mm)
 		return ERR_PTR(-EINVAL);

-	/* Only the pthreads threading model is supported. */
-	if (thread->group_leader->mm != thread->mm)
-		return ERR_PTR(-EINVAL);
-
 	process = find_process(thread, false);
 	if (!process)
 		return ERR_PTR(-EINVAL);