Re: [PATCH] arch_numa: Restore nid checks before registering a memblock with a node

[Mike Rapoport <rppt@kernel.org>]

On Thu, Nov 28, 2024 at 04:52:14PM +0000, Marc Zyngier wrote:
> Hi Mike,
> 
> On Thu, 28 Nov 2024 07:03:33 +0000,
> Mike Rapoport <rppt@kernel.org> wrote:
> > 
> > Hi Marc,
> > 
> > > diff --git a/drivers/base/arch_numa.c b/drivers/base/arch_numa.c
> > > index e187016764265..5457248eb0811 100644
> > > --- a/drivers/base/arch_numa.c
> > > +++ b/drivers/base/arch_numa.c
> > > @@ -207,7 +207,21 @@ static void __init setup_node_data(int nid, u64 start_pfn, u64 end_pfn)
> > >  static int __init numa_register_nodes(void)
> > >  {
> > >  	int nid;
> > > -
> > > +	struct memblock_region *mblk;
> > > +
> > > +	/* Check that valid nid is set to memblks */
> > > +	for_each_mem_region(mblk) {
> > > +		int mblk_nid = memblock_get_region_node(mblk);
> > > +		phys_addr_t start = mblk->base;
> > > +		phys_addr_t end = mblk->base + mblk->size - 1;
> > > +
> > > +		if (mblk_nid == NUMA_NO_NODE || mblk_nid >= MAX_NUMNODES) {
> > > +			pr_warn("Warning: invalid memblk node %d [mem %pap-%pap]\n",
> > > +				mblk_nid, &start, &end);
> > > +			return -EINVAL;
> > > +		}
> > 
> > We have memblock_validate_numa_coverage() that checks that amount of memory
> > with unset node id is less than a threshold. The loop here can be replaced
> > with something like
> > 
> > 	if (!memblock_validate_numa_coverage(0))
> > 		return -EINVAL;
> 
> Unfortunately, that doesn't seem to result in something that works
> (relevant extract only):
> 
> [    0.000000] NUMA: no nodes coverage for 9MB of 65516MB RAM
> [    0.000000] NUMA: Faking a node at [mem 0x0000000000500000-0x0000000fff0fffff]
> [    0.000000] NUMA: no nodes coverage for 0MB of 65516MB RAM
> [    0.000000] Unable to handle kernel paging request at virtual address 0000000000001d40
> 
> Any idea?

With 0 as the threshold the validation fails for the fake node, but it
should be fine with memblock_validate_numa_coverage(1)
 
> 	M.
> 
> -- 
> Without deviation from the norm, progress is not possible.

-- 
Sincerely yours,
Mike.