Re: [PATCH] driver core: ensure a device has valid node id in device_add()

Michal Hocko
2019-09-10T11:04:55Z

On Tue 10-09-19 18:58:05, Yunsheng Lin wrote:
> On 2019/9/10 17:31, Greg KH wrote:
> > On Tue, Sep 10, 2019 at 02:43:32PM +0800, Yunsheng Lin wrote:
> >> On 2019/9/9 17:53, Greg KH wrote:
> >>> On Mon, Sep 09, 2019 at 02:04:23PM +0800, Yunsheng Lin wrote:
> >>>> Currently a device does not belong to any of the numa nodes
> >>>> (dev->numa_node is NUMA_NO_NODE) when the node id is neither
> >>>> specified by fw nor by virtual device layer and the device has
> >>>> no parent device.
> >>>
> >>> Is this really a problem?
> >>
> >> Not really.
> >> Someone need to guess the node id when it is not specified, right?
> >
> > No, why? Guessing guarantees you will get it wrong on some systems.
> >
> > Are you seeing real problems because the id is not being set? What
> > problem is this fixing that you can actually observe?
>
> When passing the return value of dev_to_node() to cpumask_of_node()
> without checking the node id if the node id is not valid, there is
> global-out-of-bounds detected by KASAN as below:

OK, I seem to remember this being brought up already. And now when I
think about it, we really want to make cpumask_of_node NUMA_NO_NODE
aware. That means using the same trick the allocator does for this
special case.
--
Michal Hocko
SUSE Labs