Re: [PATCH v3 02/26] MIPS: sgi-ip27: make NODE_DATA() the same as on all other architectures

Jonathan Cameron
2024-08-01T18:46:25Z

On Thu, 1 Aug 2024 09:08:02 +0300
Mike Rapoport <rppt@kernel.org> wrote:

> From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
>
> sgi-ip27 is the only system that defines NODE_DATA() differently than
> the rest of NUMA machines.
>
> Add node_data array of struct pglist pointers that will point to
> __node_data[node]->pglist and redefine NODE_DATA() to use node_data
> array.
>
> This will allow pulling declaration of node_data to the generic mm code
> in the next commit.
>
> Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
After staring for a while at the use made of the other part
of the __node_data I think what you have in this an the next
two patches is fine.

I'm far from convinced it was correct before though as
arch_refresh_node_data() called on offline nodes in free_area_init()
would have replaced __node_data with an allocation of
size pg_data_t but the hub_data(), visible below, is after that.
Maybe hub_data() as never called for offline nodes, but
I couldn't establish that.

After these patches the arch_refresh_node_data() generic
version will only be replacing the pointer in node_data
leaving the hub_data where it was in the first place and
thus is fine.

So with that in mind (and it could be completely wrong ;)

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
> arch/mips/include/asm/mach-ip27/mmzone.h | 5 ++++-
> arch/mips/sgi-ip27/ip27-memory.c | 5 ++++-
> 2 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/arch/mips/include/asm/mach-ip27/mmzone.h b/arch/mips/include/asm/mach-ip27/mmzone.h
> index 08c36e50a860..629c3f290203 100644
> --- a/arch/mips/include/asm/mach-ip27/mmzone.h
> +++ b/arch/mips/include/asm/mach-ip27/mmzone.h
> @@ -22,7 +22,10 @@ struct node_data {
>
> extern struct node_data *__node_data[];
>
> -#define NODE_DATA(n) (&__node_data[(n)]->pglist)
> #define hub_data(n) (&__node_data[(n)]->hub)
>
> +extern struct pglist_data *node_data[];
> +
> +#define NODE_DATA(nid) (node_data[nid])
> +
> #endif /* _ASM_MACH_MMZONE_H */
> diff --git a/arch/mips/sgi-ip27/ip27-memory.c b/arch/mips/sgi-ip27/ip27-memory.c
> index b8ca94cfb4fe..c30ef6958b97 100644
> --- a/arch/mips/sgi-ip27/ip27-memory.c
> +++ b/arch/mips/sgi-ip27/ip27-memory.c
> @@ -34,8 +34,10 @@
> #define SLOT_PFNSHIFT (SLOT_SHIFT - PAGE_SHIFT)
> #define PFN_NASIDSHFT (NASID_SHFT - PAGE_SHIFT)
>
> -struct node_data *__node_data[MAX_NUMNODES];
> +struct pglist_data *node_data[MAX_NUMNODES];
> +EXPORT_SYMBOL(node_data);
>
> +struct node_data *__node_data[MAX_NUMNODES];
> EXPORT_SYMBOL(__node_data);
>
> static u64 gen_region_mask(void)
> @@ -361,6 +363,7 @@ static void __init node_mem_init(nasid_t node)
> */
> __node_data[node] = __va(slot_freepfn << PAGE_SHIFT);
> memset(__node_data[node], 0, PAGE_SIZE);
> + node_data[node] = &__node_data[node]->pglist;
>
> NODE_DATA(node)->node_start_pfn = start_pfn;
> NODE_DATA(node)->node_spanned_pages = end_pfn - start_pfn;