Re: [PATCH v3 0/5] mm: Enable CONFIG_NODES_SPAN_OTHER_NODES by default for NUMA

Baoquan He
2020-03-29T00:19:41Z

On 03/28/20 at 11:31am, Hoan Tran wrote:
> In NUMA layout which nodes have memory ranges that span across other nodes,
> the mm driver can detect the memory node id incorrectly.
>
> For example, with layout below
> Node 0 address: 0000 xxxx 0000 xxxx
> Node 1 address: xxxx 1111 xxxx 1111

Sorry, I read this example several times, but still don't get what it
means. Can it be given with real hex number address as an exmaple? I
mean just using the memory layout you have seen from some systems. The
change looks interesting though.

>
> Note:
> - Memory from low to high
> - 0/1: Node id
> - x: Invalid memory of a node
>
> When mm probes the memory map, without CONFIG_NODES_SPAN_OTHER_NODES
> config, mm only checks the memory validity but not the node id.
> Because of that, Node 1 also detects the memory from node 0 as below
> when it scans from the start address to the end address of node 1.
>
> Node 0 address: 0000 xxxx xxxx xxxx
> Node 1 address: xxxx 1111 1111 1111
>
> This layout could occur on any architecture. Most of them enables
> this config by default with CONFIG_NUMA. This patch, by default, enables
> CONFIG_NODES_SPAN_OTHER_NODES or uses early_pfn_in_nid() for NUMA.
>
> v3:
> * Revise the patch description
>
> V2:
> * Revise the patch description
>
> Hoan Tran (5):
> mm: Enable CONFIG_NODES_SPAN_OTHER_NODES by default for NUMA
> powerpc: Kconfig: Remove CONFIG_NODES_SPAN_OTHER_NODES
> x86: Kconfig: Remove CONFIG_NODES_SPAN_OTHER_NODES
> sparc: Kconfig: Remove CONFIG_NODES_SPAN_OTHER_NODES
> s390: Kconfig: Remove CONFIG_NODES_SPAN_OTHER_NODES
>
> arch/powerpc/Kconfig | 9 ---------
> arch/s390/Kconfig | 8 --------
> arch/sparc/Kconfig | 9 ---------
> arch/x86/Kconfig | 9 ---------
> mm/page_alloc.c | 2 +-
> 5 files changed, 1 insertion(+), 36 deletions(-)
>
> --
> 1.8.3.1
>
>