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? > According to discussion in [1]: > Even if a device's numa node is not specified, the device really > does belong to a node. But as we do not know the node, can we cause more harm by randomly picking one (i.e. putting it all in node 0)? > This patch sets the device node to node 0 in device_add() if the > device's node id is not specified and it either has no parent > device, or the parent device also does not have a valid node id. > > [1] https://lkml.org/lkml/2019/9/2/466 > > Signed-off-by: Yunsheng Lin <linyunsh...@huawei.com> > --- > Changelog RFC -> v1: > 1. Drop log error message and use a "if" instead of "? :". > 2. Drop the RFC tag. > --- > drivers/base/core.c | 10 +++++++--- > include/linux/numa.h | 2 ++ > 2 files changed, 9 insertions(+), 3 deletions(-) > > diff --git a/drivers/base/core.c b/drivers/base/core.c > index 1669d41..f79ad20 100644 > --- a/drivers/base/core.c > +++ b/drivers/base/core.c > @@ -2107,9 +2107,13 @@ int device_add(struct device *dev) > if (kobj) > dev->kobj.parent = kobj; > > - /* use parent numa_node */ > - if (parent && (dev_to_node(dev) == NUMA_NO_NODE)) > - set_dev_node(dev, dev_to_node(parent)); > + /* use parent numa_node or default node 0 */ > + if (!numa_node_valid(dev_to_node(dev))) { > + if (parent && numa_node_valid(dev_to_node(parent))) > + set_dev_node(dev, dev_to_node(parent)); > + else > + set_dev_node(dev, 0); > + } Again, is this going to cause more harm than good? What happens if we leave it as "unknown", isn't that better than thinking we "know" it is in node 0? thanks, greg k-h
