Re: [RFC PATCH v9 3/4] drm/virtio: implement userptr resource support

[Dmitry Osipenko]

24.09.2026 12:55, Honglei Huang пишет:
> +	mm = current->mm;
> +	mmgrab(mm);
> +	lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
> +	new_pinned = atomic64_add_return(userptr->npages, &mm->pinned_vm);
> +	if (new_pinned < 0 ||
> +	    (new_pinned > lock_limit && !capable(CAP_IPC_LOCK))) {
> +		atomic64_sub(userptr->npages, &mm->pinned_vm)

At a quick glance over other kernel code touching pinned_vm, nobody else
check for new_pinned < 0 and then doing atomic64_sub() for the negative
value will be incorrect.

-- 
Best regards,
Dmitry