Re: [PATCH v3] mm: fix panic in __alloc_pages

Michal Hocko
2021-12-17T12:53:45Z

On Fri 10-12-21 10:11:14, Michal Hocko wrote:
> On Thu 09-12-21 19:01:03, Alexey Makhalov wrote:
> >
> >
> > > On Dec 9, 2021, at 5:29 AM, Michal Hocko <mhocko@suse.com> wrote:
> > >
> > > On Thu 09-12-21 10:23:52, Alexey Makhalov wrote:
> > >>
> > >>
> > >>> On Dec 9, 2021, at 1:56 AM, Michal Hocko <mhocko@suse.com> wrote:
> > >>>
> > >>> On Thu 09-12-21 09:28:55, Alexey Makhalov wrote:
> > >>>>
> > >>>>
> > >>>> [ 0.081777] Node 4 uninitialized by the platform. Please report with boot dmesg.
> > >>>> [ 0.081790] Initmem setup node 4 [mem 0x0000000000000000-0x0000000000000000]
> > >>>> ...
> > >>>> [ 0.086441] Node 127 uninitialized by the platform. Please report with boot dmesg.
> > >>>> [ 0.086454] Initmem setup node 127 [mem 0x0000000000000000-0x0000000000000000]
> > >>>
> > >>> Interesting that only those two didn't get a proper arch specific
> > >>> initialization. Could you check why? I assume init_cpu_to_node
> > >>> doesn't see any CPU pointing at this node. Wondering why that would be
> > >>> the case but that can be a bug in the affinity tables.
> > >>
> > >> My bad shrinking. Not just these 2, but all possible and not present nodes from 4 to 127
> > >> are having this message.
> > >
> > > Does that mean that your possible (but offline) cpus do not set their
> > > affinity?
> > >
> > Hi Michal,
> >
> > I didn’t quite gut a question here. Do you mean scheduler affinity for offlined/not present CPUs?
> > From the patch, this message should be printed for every possible offlined node:
> > for_each_node(nid) {
> > ...
> > if (!node_online(nid)) {
> > pr_warn("Node %d uninitialized by the platform. Please report with boot dmesg.\n", nid);
>
> Sure, let me expand on this a bit. X86 initialization code
> (init_cpu_to_node) does
> for_each_possible_cpu(cpu) {
> int node = numa_cpu_node(cpu);
>
> if (node == NUMA_NO_NODE)
> continue;
>
> if (!node_online(node))
> init_memory_less_node(node);
>
> numa_set_node(cpu, node);
> }
>
> which means that a memory less node is not initialized either when
> - your offline CPUs are not listed in possible cpus for some
> reason
> - or they do not have any node affinity (numa_cpu_node is
> NUMA_NO_NODE).
>
> Could you check what is the reason in your particular case please?

Did you have time to look into this Alexey?
--
Michal Hocko
SUSE Labs