On Tue, Sep 24, 2019 at 01:54:01PM +0200, Michal Hocko wrote: > On Tue 24-09-19 13:23:49, Peter Zijlstra wrote: > > On Tue, Sep 24, 2019 at 12:56:22PM +0200, Michal Hocko wrote: > [...] > > > To be honest I really fail to see why to object to a simple semantic > > > that NUMA_NO_NODE imply all usable cpus. Could you explain that please? > > > > Because it feels wrong. The device needs to be _somewhere_. It simply > > cannot be node-less. > > What if it doesn't have any numa preference for what ever reason? There > is no other way to express that than NUMA_NO_NODE. Like I said; how does that physically work? The device needs to be somewhere. It _must_ have a preference. > Anyway, I am not going to argue more about this because it seems more of > a discussion about "HW shouldn't be doing that although the specification > allows that" which cannot really have any outcome except of "feels > correct/wrong". We can push back and say we don't respect the specification because it is batshit insane ;-) > If you really feel strongly about this then we should think of a proper > way to prevent this to happen because an out-of-bound access is > certainly not something we really want, right? I just genuinely don't understand it. And I refuse to duct tape it. And as shown in that email here: https://lkml.kernel.org/r/5a188e2b-6c07-a9db-fbaa-561e9362d3ba@xxxxxxxxxx there is a ton of broken... 15.061682] node node0: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. ... 15.285602] node node3: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. 15.360241] cpu cpu0: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. ... 24.768305] cpu cpu127: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. 39.623339] clockevents clockevent0: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. ... 48.769530] clockevents clockevent127: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. That's all broken for no reason.. those things actually _have_ a trivial node affinity. By silently accepting we let this stuff fester. Now granted; there's a number of virtual devices that really don't have a node affinity, but then, those are not hurt by forcing them onto a random node, they really don't do anything. Like: 48.913502] event_source armv8_pmuv3_0: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. 48.985462] event_source breakpoint: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. 49.057120] event_source uprobe: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. 49.128431] event_source kprobe: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. 49.199742] event_source tracepoint: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. 49.271399] event_source software: has invalid NUMA node(-1), default node of 0 now selected. Readjust it by writing to sysfs numa_node or contact your vendor for updates. That's just fake devices to get a sysfs entry.
