[PATCH 0/7] don't abuse task_struct.group_leader

[PATCH 0/7] don't abuse task_struct.group_leader

[Oleg Nesterov]

Hello.

Untested but hopefully trivial, please review.

The patches do not depend on each other, this series just removes
the usage of ->group_leader when it is "obviously unnecessary".

I am going to move ->group_leader from task_struct to signal_struct
or at least add the new task_group_leader() helper. So I will send
more tree-wide changes on top of this series.

If this series passes the review, can it be routed via mm tree?

Oleg.
---
 drivers/android/binder.c                         |  9 ++++-----
 drivers/android/binder_alloc.c                   |  2 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c |  2 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c           |  5 +----
 drivers/gpu/drm/amd/amdkfd/kfd_process.c         | 10 ----------
 drivers/gpu/drm/panfrost/panfrost_gem.c          |  2 +-
 drivers/gpu/drm/panthor/panthor_gem.c            |  2 +-
 drivers/infiniband/core/umem_odp.c               |  4 ++--
 net/core/netclassid_cgroup.c                     |  2 +-
 9 files changed, 12 insertions(+), 26 deletions(-)

[PATCH 1/7] android/binder: don't abuse current->group_leader

[Oleg Nesterov]

Cleanup and preparation to simplify the next changes.

- Use current->tgid instead of current->group_leader->pid

- Use the value returned by get_task_struct() to initialize proc->tsk

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
 drivers/android/binder.c       | 7 +++----
 drivers/android/binder_alloc.c | 2 +-
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index a3a1b5c33ba3..a00f6678f04d 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -6044,7 +6044,7 @@ static int binder_open(struct inode *nodp, struct file *filp)
 	bool existing_pid = false;
 
 	binder_debug(BINDER_DEBUG_OPEN_CLOSE, "%s: %d:%d\n", __func__,
-		     current->group_leader->pid, current->pid);
+		     current->tgid, current->pid);
 
 	proc = kzalloc(sizeof(*proc), GFP_KERNEL);
 	if (proc == NULL)
@@ -6053,8 +6053,8 @@ static int binder_open(struct inode *nodp, struct file *filp)
 	dbitmap_init(&proc->dmap);
 	spin_lock_init(&proc->inner_lock);
 	spin_lock_init(&proc->outer_lock);
-	get_task_struct(current->group_leader);
-	proc->tsk = current->group_leader;
+	proc->tsk = get_task_struct(current->group_leader);
+	proc->pid = current->tgid;
 	proc->cred = get_cred(filp->f_cred);
 	INIT_LIST_HEAD(&proc->todo);
 	init_waitqueue_head(&proc->freeze_wait);
@@ -6073,7 +6073,6 @@ static int binder_open(struct inode *nodp, struct file *filp)
 	binder_alloc_init(&proc->alloc);
 
 	binder_stats_created(BINDER_STAT_PROC);
-	proc->pid = current->group_leader->pid;
 	INIT_LIST_HEAD(&proc->delivered_death);
 	INIT_LIST_HEAD(&proc->delivered_freeze);
 	INIT_LIST_HEAD(&proc->waiting_threads);
diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index 979c96b74cad..145ed5f14cdb 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -1233,7 +1233,7 @@ static struct shrinker *binder_shrinker;
 VISIBLE_IF_KUNIT void __binder_alloc_init(struct binder_alloc *alloc,
 					  struct list_lru *freelist)
 {
-	alloc->pid = current->group_leader->pid;
+	alloc->pid = current->tgid;
 	alloc->mm = current->mm;
 	mmgrab(alloc->mm);
 	mutex_init(&alloc->mutex);
-- 
2.52.0

[PATCH 2/7] android/binder: use same_thread_group(proc->tsk, current) in binder_mmap()

[Oleg Nesterov]

With or without this change the checked condition can be falsely true
if proc->tsk execs, but this is fine: binder_alloc_mmap_handler() checks
vma->vm_mm == alloc->mm.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
 drivers/android/binder.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index a00f6678f04d..980bb13228fc 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -6013,7 +6013,7 @@ static int binder_mmap(struct file *filp, struct vm_area_struct *vma)
 {
 	struct binder_proc *proc = filp->private_data;
 
-	if (proc->tsk != current->group_leader)
+	if (!same_thread_group(proc->tsk, current))
 		return -EINVAL;
 
 	binder_debug(BINDER_DEBUG_OPEN_CLOSE,
-- 
2.52.0

[PATCH 3/7] drm/amdgpu: don't abuse current->group_leader

[Oleg Nesterov]

Cleanup and preparation to simplify the next changes.

- Use current->tgid instead of current->group_leader->pid

- Use get_task_pid(current, PIDTYPE_TGID) instead of
  get_task_pid(current->group_leader, PIDTYPE_PID)

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 2 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c           | 2 +-
 2 files changed, 2 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 b1c24c8fa686..df22b54ba346 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -1421,7 +1421,7 @@ static int init_kfd_vm(struct amdgpu_vm *vm, void **process_info,
 			goto create_evict_fence_fail;
 		}
 
-		info->pid = get_task_pid(current->group_leader, PIDTYPE_PID);
+		info->pid = get_task_pid(current, PIDTYPE_TGID);
 		INIT_DELAYED_WORK(&info->restore_userptr_work,
 				  amdgpu_amdkfd_restore_userptr_worker);
 
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index a67285118c37..a0f8ba382b9e 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -2554,7 +2554,7 @@ void amdgpu_vm_set_task_info(struct amdgpu_vm *vm)
 	if (current->group_leader->mm != current->mm)
 		return;
 
-	vm->task_info->tgid = current->group_leader->pid;
+	vm->task_info->tgid = current->tgid;
 	get_task_comm(vm->task_info->process_name, current->group_leader);
 }
 
-- 
2.52.0

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

[Oleg Nesterov]

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().

I don't think that drm/amd tries to detect/nack this case.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
 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);
-- 
2.52.0

[PATCH 5/7] drm/pan*: don't abuse current->group_leader

[Oleg Nesterov]

Cleanup and preparation to simplify the next changes.

Use current->tgid instead of current->group_leader->pid.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
 drivers/gpu/drm/panfrost/panfrost_gem.c | 2 +-
 drivers/gpu/drm/panthor/panthor_gem.c   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c
index 8041b65c6609..1ff1f2c8b726 100644
--- a/drivers/gpu/drm/panfrost/panfrost_gem.c
+++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
@@ -17,7 +17,7 @@
 static void panfrost_gem_debugfs_bo_add(struct panfrost_device *pfdev,
 					struct panfrost_gem_object *bo)
 {
-	bo->debugfs.creator.tgid = current->group_leader->pid;
+	bo->debugfs.creator.tgid = current->tgid;
 	get_task_comm(bo->debugfs.creator.process_name, current->group_leader);
 
 	mutex_lock(&pfdev->debugfs.gems_lock);
diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c
index fbde78db270a..29cc57efc4b9 100644
--- a/drivers/gpu/drm/panthor/panthor_gem.c
+++ b/drivers/gpu/drm/panthor/panthor_gem.c
@@ -27,7 +27,7 @@ static void panthor_gem_debugfs_bo_add(struct panthor_gem_object *bo)
 	struct panthor_device *ptdev = container_of(bo->base.base.dev,
 						    struct panthor_device, base);
 
-	bo->debugfs.creator.tgid = current->group_leader->pid;
+	bo->debugfs.creator.tgid = current->tgid;
 	get_task_comm(bo->debugfs.creator.process_name, current->group_leader);
 
 	mutex_lock(&ptdev->gems.lock);
-- 
2.52.0

[PATCH 6/7] RDMA/umem: don't abuse current->group_leader

[Oleg Nesterov]

Cleanup and preparation to simplify the next changes.

Use current->tgid instead of current->group_leader->pid.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
 drivers/infiniband/core/umem_odp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
index 572a91a62a7b..32267258a19c 100644
--- a/drivers/infiniband/core/umem_odp.c
+++ b/drivers/infiniband/core/umem_odp.c
@@ -149,7 +149,7 @@ struct ib_umem_odp *ib_umem_odp_alloc_implicit(struct ib_device *device,
 	umem->owning_mm = current->mm;
 	umem_odp->page_shift = PAGE_SHIFT;
 
-	umem_odp->tgid = get_task_pid(current->group_leader, PIDTYPE_PID);
+	umem_odp->tgid = get_task_pid(current, PIDTYPE_TGID);
 	ib_init_umem_implicit_odp(umem_odp);
 	return umem_odp;
 }
@@ -258,7 +258,7 @@ struct ib_umem_odp *ib_umem_odp_get(struct ib_device *device,
 		umem_odp->page_shift = HPAGE_SHIFT;
 #endif
 
-	umem_odp->tgid = get_task_pid(current->group_leader, PIDTYPE_PID);
+	umem_odp->tgid = get_task_pid(current, PIDTYPE_TGID);
 	ret = ib_init_umem_odp(umem_odp, ops);
 	if (ret)
 		goto err_put_pid;
-- 
2.52.0

[PATCH 7/7] netclassid: use thread_group_leader(p) in update_classid_task()

[Oleg Nesterov]

Cleanup and preparation to simplify the next changes.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
 net/core/netclassid_cgroup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/netclassid_cgroup.c b/net/core/netclassid_cgroup.c
index dff66d8fb325..db9a5354f9de 100644
--- a/net/core/netclassid_cgroup.c
+++ b/net/core/netclassid_cgroup.c
@@ -93,7 +93,7 @@ static void update_classid_task(struct task_struct *p, u32 classid)
 	/* Only update the leader task, when many threads in this task,
 	 * so it can avoid the useless traversal.
 	 */
-	if (p != p->group_leader)
+	if (!thread_group_leader(p))
 		return;
 
 	do {
-- 
2.52.0

Re: [PATCH 5/7] drm/pan*: don't abuse current->group_leader

[Boris Brezillon]

On Sun, 7 Dec 2025 13:39:53 +0100
Oleg Nesterov <oleg@redhat.com> wrote:

> Cleanup and preparation to simplify the next changes.
> 
> Use current->tgid instead of current->group_leader->pid.
> 
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
> ---
>  drivers/gpu/drm/panfrost/panfrost_gem.c | 2 +-
>  drivers/gpu/drm/panthor/panthor_gem.c   | 2 +-

Acked-by: Boris Brezillon <boris.brezillon@collabora.com>

>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c
> index 8041b65c6609..1ff1f2c8b726 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gem.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
> @@ -17,7 +17,7 @@
>  static void panfrost_gem_debugfs_bo_add(struct panfrost_device *pfdev,
>  					struct panfrost_gem_object *bo)
>  {
> -	bo->debugfs.creator.tgid = current->group_leader->pid;
> +	bo->debugfs.creator.tgid = current->tgid;
>  	get_task_comm(bo->debugfs.creator.process_name, current->group_leader);
>  
>  	mutex_lock(&pfdev->debugfs.gems_lock);
> diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c
> index fbde78db270a..29cc57efc4b9 100644
> --- a/drivers/gpu/drm/panthor/panthor_gem.c
> +++ b/drivers/gpu/drm/panthor/panthor_gem.c
> @@ -27,7 +27,7 @@ static void panthor_gem_debugfs_bo_add(struct panthor_gem_object *bo)
>  	struct panthor_device *ptdev = container_of(bo->base.base.dev,
>  						    struct panthor_device, base);
>  
> -	bo->debugfs.creator.tgid = current->group_leader->pid;
> +	bo->debugfs.creator.tgid = current->tgid;
>  	get_task_comm(bo->debugfs.creator.process_name, current->group_leader);
>  
>  	mutex_lock(&ptdev->gems.lock);

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

[Christian König]

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@redhat.com>

Seems to make sense of hand.

Reviewed-by: Christian König <christian.koenig@amd.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);

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

[Oleg Nesterov]

On 12/08, Christian König wrote:
>
> 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?

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.
>
> > ---
> >  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);
>

Re: [PATCH 3/7] drm/amdgpu: don't abuse current->group_leader

[Felix Kuehling]

On 2025-12-07 07:39, Oleg Nesterov wrote:
> Cleanup and preparation to simplify the next changes.
>
> - Use current->tgid instead of current->group_leader->pid
>
> - Use get_task_pid(current, PIDTYPE_TGID) instead of
>    get_task_pid(current->group_leader, PIDTYPE_PID)
>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>

Acked-by: Felix Kuehling <felix.kuehling@amd.com>


> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 2 +-
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c           | 2 +-
>   2 files changed, 2 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 b1c24c8fa686..df22b54ba346 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> @@ -1421,7 +1421,7 @@ static int init_kfd_vm(struct amdgpu_vm *vm, void **process_info,
>   			goto create_evict_fence_fail;
>   		}
>   
> -		info->pid = get_task_pid(current->group_leader, PIDTYPE_PID);
> +		info->pid = get_task_pid(current, PIDTYPE_TGID);
>   		INIT_DELAYED_WORK(&info->restore_userptr_work,
>   				  amdgpu_amdkfd_restore_userptr_worker);
>   
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> index a67285118c37..a0f8ba382b9e 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> @@ -2554,7 +2554,7 @@ void amdgpu_vm_set_task_info(struct amdgpu_vm *vm)
>   	if (current->group_leader->mm != current->mm)
>   		return;
>   
> -	vm->task_info->tgid = current->group_leader->pid;
> +	vm->task_info->tgid = current->tgid;
>   	get_task_comm(vm->task_info->process_name, current->group_leader);
>   }
>   

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

[Felix Kuehling]

On 2025-12-07 07:39, 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().
>
> I don't think that drm/amd tries to detect/nack this case.
>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>

Acked-by: Felix Kuehling <felix.kuehling@amd.com>


> ---
>   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);

Re: [PATCH 5/7] drm/pan*: don't abuse current->group_leader

[Steven Price]

On 07/12/2025 12:39, Oleg Nesterov wrote:
> Cleanup and preparation to simplify the next changes.
> 
> Use current->tgid instead of current->group_leader->pid.
> 
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>

Acked-by: Steven Price <steven.price@arm.com>

> ---
>  drivers/gpu/drm/panfrost/panfrost_gem.c | 2 +-
>  drivers/gpu/drm/panthor/panthor_gem.c   | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c
> index 8041b65c6609..1ff1f2c8b726 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gem.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
> @@ -17,7 +17,7 @@
>  static void panfrost_gem_debugfs_bo_add(struct panfrost_device *pfdev,
>  					struct panfrost_gem_object *bo)
>  {
> -	bo->debugfs.creator.tgid = current->group_leader->pid;
> +	bo->debugfs.creator.tgid = current->tgid;
>  	get_task_comm(bo->debugfs.creator.process_name, current->group_leader);
>  
>  	mutex_lock(&pfdev->debugfs.gems_lock);
> diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c
> index fbde78db270a..29cc57efc4b9 100644
> --- a/drivers/gpu/drm/panthor/panthor_gem.c
> +++ b/drivers/gpu/drm/panthor/panthor_gem.c
> @@ -27,7 +27,7 @@ static void panthor_gem_debugfs_bo_add(struct panthor_gem_object *bo)
>  	struct panthor_device *ptdev = container_of(bo->base.base.dev,
>  						    struct panthor_device, base);
>  
> -	bo->debugfs.creator.tgid = current->group_leader->pid;
> +	bo->debugfs.creator.tgid = current->tgid;
>  	get_task_comm(bo->debugfs.creator.process_name, current->group_leader);
>  
>  	mutex_lock(&ptdev->gems.lock);

Re: [PATCH 2/7] android/binder: use same_thread_group(proc->tsk, current) in binder_mmap()

[Alice Ryhl]

On Sun, Dec 7, 2025 at 1:40 PM Oleg Nesterov <oleg@redhat.com> wrote:
>
> With or without this change the checked condition can be falsely true
> if proc->tsk execs, but this is fine: binder_alloc_mmap_handler() checks
> vma->vm_mm == alloc->mm.
>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>

Reviewed-by: Alice Ryhl <aliceryhl@google.com>

Re: [PATCH 1/7] android/binder: don't abuse current->group_leader

[Alice Ryhl]

On Sun, Dec 7, 2025 at 1:39 PM Oleg Nesterov <oleg@redhat.com> wrote:
>
> Cleanup and preparation to simplify the next changes.
>
> - Use current->tgid instead of current->group_leader->pid
>
> - Use the value returned by get_task_struct() to initialize proc->tsk
>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>

Reviewed-by: Alice Ryhl <aliceryhl@google.com>

Re: [PATCH 6/7] RDMA/umem: don't abuse current->group_leader

[Leon Romanovsky]

On Sun, Dec 07, 2025 at 01:40:05PM +0100, Oleg Nesterov wrote:
> Cleanup and preparation to simplify the next changes.
> 
> Use current->tgid instead of current->group_leader->pid.
> 
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
> ---
>  drivers/infiniband/core/umem_odp.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 

Thanks,
Acked-by: Leon Romanovsky <leon@kernel.org>