Re: [PATCH 05/17] arch, mm: pull out allocation of NODE_DATA to generic code

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Fri, 19 Jul 2024 17:07:35 +0200
David Hildenbrand <david@redhat.com> wrote:

> >>> -	 * Allocate node data.  Try node-local memory and then any node.
> >>> -	 * Never allocate in DMA zone.
> >>> -	 */
> >>> -	nd_pa = memblock_phys_alloc_try_nid(nd_size, SMP_CACHE_BYTES, nid);
> >>> -	if (!nd_pa) {
> >>> -		pr_err("Cannot find %zu bytes in any node (initial node: %d)\n",
> >>> -		       nd_size, nid);
> >>> -		return;
> >>> -	}
> >>> -	nd = __va(nd_pa);
> >>> -
> >>> -	/* report and initialize */
> >>> -	printk(KERN_INFO "NODE_DATA(%d) allocated [mem %#010Lx-%#010Lx]\n", nid,
> >>> -	       nd_pa, nd_pa + nd_size - 1);
> >>> -	tnid = early_pfn_to_nid(nd_pa >> PAGE_SHIFT);
> >>> -	if (tnid != nid)
> >>> -		printk(KERN_INFO "    NODE_DATA(%d) on node %d\n", nid, tnid);
> >>> -
> >>> -	node_data[nid] = nd;
> >>> -	memset(NODE_DATA(nid), 0, sizeof(pg_data_t));
> >>> -
> >>> -	node_set_online(nid);
> >>> -}
> >>> -
> >>>    /**
> >>>     * numa_cleanup_meminfo - Cleanup a numa_meminfo
> >>>     * @mi: numa_meminfo to clean up
> >>> @@ -571,6 +538,7 @@ static int __init numa_register_memblks(struct numa_meminfo *mi)
> >>>    			continue;
> >>>    		alloc_node_data(nid);
> >>> +		node_set_online(nid);
> >>>    	}  
> >>
> >> I can spot that we only remove a single node_set_online() call from x86.
> >>
> >> What about all the other architectures? Will there be any change in behavior
> >> for them? Or do we simply set the nodes online later once more?  
> > 
> > On x86 node_set_online() was a part of alloc_node_data() and I moved it
> > outside so it's called right after alloc_node_data(). On other
> > architectures the allocation didn't include that call, so there should be
> > no difference there.  
> 
> But won't their arch code try setting the nodes online at a later stage?
> 
> And I think, some architectures only set nodes online conditionally
> (see most other node_set_online() calls).
> 
> Sorry if I'm confused here, but with now unconditional node_set_online(), won't
> we change the behavior of other architectures?
This is moving x86 code to x86 code, not a generic location
so how would that affect anyone else? Their onlining should be same as
before.

The node onlining difference are a pain (I recall that fun from adding
generic initiators) as different ordering on x86 and arm64 at least.

Jonathan

>