Re: CVE-2024-26628: drm/amdkfd: Fix lock dependency warning

[Michal Hocko]

On Wed 06-03-24 06:46:11, Greg KH wrote:
[...]
>  Possible unsafe locking scenario:
> 
>        CPU0                    CPU1
>        ----                    ----
>   lock(&svms->lock);
>                                lock(&mm->mmap_lock);
>                                lock(&svms->lock);
>   lock((work_completion)(&svm_bo->eviction_work));
> 
> I believe this cannot really lead to a deadlock in practice, because
> svm_range_evict_svm_bo_worker only takes the mmap_read_lock if the BO
> refcount is non-0. That means it's impossible that svm_range_bo_release
> is running concurrently. However, there is no good way to annotate this.

OK, so is this even a bug (not to mention a security/weakness)?
-- 
Michal Hocko
SUSE Labs