linux-kernel - Re: [PATCH 4/7] drm/amd: kill the outdated "Only the pthreads threading model is supported" checks

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <e8846bef-2a6b-4552-8fb6-a33a00273aab@amd.com>
Date: Mon, 8 Dec 2025 09:28:01 +0100
From: Christian König <christian.koenig@....com>
To: Oleg Nesterov <oleg@...hat.com>, Todd Kjos <tkjos@...roid.com>,
 Martijn Coenen <maco@...roid.com>, Joel Fernandes <joelagnelf@...dia.com>,
 Christian Brauner <brauner@...nel.org>, Carlos Llamas <cmllamas@...gle.com>,
 Suren Baghdasaryan <surenb@...gle.com>,
 Felix Kuehling <Felix.Kuehling@....com>,
 Alex Deucher <alexander.deucher@....com>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>,
 Boris Brezillon <boris.brezillon@...labora.com>,
 Rob Herring <robh@...nel.org>, Steven Price <steven.price@....com>,
 Adrián Larumbe <adrian.larumbe@...labora.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 Liviu Dudau <liviu.dudau@....com>, Jason Gunthorpe <jgg@...pe.ca>,
 Leon Romanovsky <leon@...nel.org>, "David S. Miller" <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>
Cc: linux-kernel@...r.kernel.org, amd-gfx@...ts.freedesktop.org,
 dri-devel@...ts.freedesktop.org, linux-rdma@...r.kernel.org,
 netdev@...r.kernel.org
Subject: Re: [PATCH 4/7] drm/amd: kill the outdated "Only the pthreads
 threading model is supported" checks

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

> 
> I don't think that drm/amd tries to detect/nack this case.
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>

Seems to make sense of hand.

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

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

Regards,
Christian.

> ---
>  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);