Messages in this thread |  | | Date | Fri, 6 Sep 2019 16:00:25 +0200 | From | Greg KH <> | Subject | Re: [PATCH RFC] driver core: ensure a device has valid node id in device_add() |
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On Fri, Sep 06, 2019 at 04:21:47PM +0800, Yunsheng Lin wrote: > On 2019/9/6 14:52, Greg KH wrote: > > On Fri, Sep 06, 2019 at 02:41:36PM +0800, Yunsheng Lin wrote: > >> On 2019/9/5 15:33, Greg KH wrote: > >>> On Thu, Sep 05, 2019 at 02:48:24PM +0800, Yunsheng Lin wrote: > >>>> On 2019/9/5 13:57, Greg KH wrote: > >>>>> On Thu, Sep 05, 2019 at 09:33:50AM +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 FW does not provide > >>>>>> the node id and the device has not no parent device. > >>>>>> > >>>>>> According to discussion in [1]: > >>>>>> Even if a device's numa node is not set by fw, the device > >>>>>> really does belong to a node. > >>>>>> > >>>>>> This patch sets the device node to node 0 in device_add() if > >>>>>> the fw has not specified the node id and it either has no > >>>>>> parent device, or the parent device also does not have a valid > >>>>>> node id. > >>>>>> > >>>>>> There may be explicit handling out there relying on NUMA_NO_NODE, > >>>>>> like in nvme_probe(). > >>>>>> > >>>>>> [1] https://lkml.org/lkml/2019/9/2/466 > >>>>>> > >>>>>> Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com> > >>>>>> --- > >>>>>> drivers/base/core.c | 17 ++++++++++++++--- > >>>>>> include/linux/numa.h | 2 ++ > >>>>>> 2 files changed, 16 insertions(+), 3 deletions(-) > >>>>>> > >>>>>> diff --git a/drivers/base/core.c b/drivers/base/core.c > >>>>>> index 1669d41..466b8ff 100644 > >>>>>> --- a/drivers/base/core.c > >>>>>> +++ b/drivers/base/core.c > >>>>>> @@ -2107,9 +2107,20 @@ 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))) { > >>>>>> + int nid = parent ? dev_to_node(parent) : NUMA_NO_NODE; > >>>>> > >>>>> Can you expand this to be a "real" if statement please? > >>>> > >>>> Sure. May I ask why "? :" is not appropriate here? > >>> > >>> Because it is a pain to read, just spell it out and make it obvious what > >>> is happening. You write code for developers first, and the compiler > >>> second, and in this case, either way is identical to the compiler. > >>> > >>>>>> + > >>>>>> + if (numa_node_valid(nid)) { > >>>>>> + set_dev_node(dev, nid); > >>>>>> + } else { > >>>>>> + if (nr_node_ids > 1U) > >>>>>> + pr_err("device: '%s': has invalid NUMA node(%d)\n", > >>>>>> + dev_name(dev), dev_to_node(dev)); > >>>>> > >>>>> dev_err() will show you the exact device properly, instead of having to > >>>>> rely on dev_name(). > >>>>> > >>>>> And what is a user to do if this message happens? How do they fix this? > >>>>> If they can not, what good is this error message? > >>>> > >>>> If user know about their system's topology well enough and node 0 > >>>> is not the nearest node to the device, maybe user can readjust that by > >>>> writing the nearest node to /sys/class/pci_bus/XXXX/device/numa_node, > >>>> if not, then maybe user need to contact the vendor for info or updates. > >>>> > >>>> Maybe print error message as below: > >>>> > >>>> dev_err(dev, FW_BUG "has invalid NUMA node(%d). Readjust it by writing to sysfs numa_node or contact your vendor for updates.\n", > >>>> dev_to_node(dev)); > >>> > >>> FW_BUG? > >>> > >>> Anyway, if you make this change, how many machines start reporting this > >>> error? > >> > >> Any machines with more than one numa node will start reporting this error. > >> > >> 1) many virtual deivces maybe do not set the node id before calling > >> device_register(), such as vfio, tun, etc. > >> > >> 2) struct cpu has a dev, but does not set the dev' node according to > >> cpu_to_node(). > >> > >> 3) Many platform Device also do not have a node id provided by FW. > > > > Then this patch is not ok, as you are flooding the kernel log saying the > > system is "broken" when this is just what it always has been like. How > > is anyone going to "fix" things? > > cpu->node_id does not seem to be used, maybe we can fix the cpu device: > > diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c > index cc37511d..ad0a841 100644 > --- a/drivers/base/cpu.c > +++ b/drivers/base/cpu.c > @@ -41,7 +41,7 @@ static void change_cpu_under_node(struct cpu *cpu, > int cpuid = cpu->dev.id; > unregister_cpu_under_node(cpuid, from_nid); > register_cpu_under_node(cpuid, to_nid); > - cpu->node_id = to_nid; > + set_dev_node(&cpu->dev, to_nid); > } > > static int cpu_subsys_online(struct device *dev) > @@ -367,7 +367,7 @@ int register_cpu(struct cpu *cpu, int num) > { > int error; > > - cpu->node_id = cpu_to_node(num); > + set_dev_node(&cpu->dev, cpu_to_node(num)); > memset(&cpu->dev, 0x00, sizeof(struct device)); > cpu->dev.id = num; > cpu->dev.bus = &cpu_subsys; > diff --git a/include/linux/cpu.h b/include/linux/cpu.h > index fcb1386..9a6fc51 100644 > --- a/include/linux/cpu.h > +++ b/include/linux/cpu.h > @@ -24,7 +24,6 @@ struct device_node; > struct attribute_group; > > struct cpu { > - int node_id; /* The node which contains the CPU */ > int hotpluggable; /* creates sysfs control file if hotpluggable */ > struct device dev; > };
I have no idea what you are trying to do here, it feels like you are flailing around trying to set something that almost no bios/firmware sets or cares about.
If setting the proper node is a requirement, make sure your firmware does this and then all should be fine. Otherwise just use the default node like what happens today, right?
thanks,
greg k-h
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