Subject: Re: [PATCH 01/21] mm: memblock: replace dereferences of memblock_region.nid with API calls

From: Baoquan He <[email-masked]>
Date: Tue, 21 Apr 2020 10:06:03 +0800

On 04/12/20 at 10:48pm, Mike Rapoport wrote:
> From: Mike Rapoport <[email-masked]>
> 
> There are several places in the code that directly dereference
> memblock_region.nid despite this field being defined only when
> CONFIG_HAVE_MEMBLOCK_NODE_MAP=y.
> 
> Replace these with calls to memblock_get_region_nid() to improve code
> robustness and to avoid possible breakage when
> CONFIG_HAVE_MEMBLOCK_NODE_MAP will be removed.
> 
> Signed-off-by: Mike Rapoport <[email-masked]>
> ---
>  arch/arm64/mm/numa.c | 9 ++++++---
>  arch/x86/mm/numa.c   | 6 ++++--
>  mm/memblock.c        | 8 +++++---
>  mm/page_alloc.c      | 4 ++--
>  4 files changed, 17 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
> index 4decf1659700..aafcee3e3f7e 100644
> --- a/arch/arm64/mm/numa.c
> +++ b/arch/arm64/mm/numa.c
> @@ -350,13 +350,16 @@ static int __init numa_register_nodes(void)
>  	struct memblock_region *mblk;
>  
>  	/* Check that valid nid is set to memblks */
> -	for_each_memblock(memory, mblk)
> -		if (mblk->nid == NUMA_NO_NODE || mblk->nid >= MAX_NUMNODES) {
> +	for_each_memblock(memory, mblk) {
> +		int mblk_nid = memblock_get_region_node(mblk);
> +
> +		if (mblk_nid == NUMA_NO_NODE || mblk_nid >= MAX_NUMNODES) {
>  			pr_warn("Warning: invalid memblk node %d [mem %#010Lx-%#010Lx]\n",
> -				mblk->nid, mblk->base,
> +				mblk_nid, mblk->base,
>  				mblk->base + mblk->size - 1);
>  			return -EINVAL;
>  		}
> +	}
>  
>  	/* Finally register nodes. */
>  	for_each_node_mask(nid, numa_nodes_parsed) {
> diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
> index 59ba008504dc..fe024b2ac796 100644
> --- a/arch/x86/mm/numa.c
> +++ b/arch/x86/mm/numa.c
> @@ -517,8 +517,10 @@ static void __init numa_clear_kernel_node_hotplug(void)
>  	 *   reserve specific pages for Sandy Bridge graphics. ]
>  	 */
>  	for_each_memblock(reserved, mb_region) {
> -		if (mb_region->nid != MAX_NUMNODES)
> -			node_set(mb_region->nid, reserved_nodemask);
> +		int nid = memblock_get_region_node(mb_region);
> +
> +		if (nid != MAX_NUMNODES)
> +			node_set(nid, reserved_nodemask);
>  	}
>  
>  	/*
> diff --git a/mm/memblock.c b/mm/memblock.c
> index c79ba6f9920c..43e2fd3006c1 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -1207,13 +1207,15 @@ void __init_memblock __next_mem_pfn_range(int *idx, int nid,
>  {
>  	struct memblock_type *type = &memblock.memory;
>  	struct memblock_region *r;
> +	int r_nid;
>  
>  	while (++*idx < type->cnt) {
>  		r = &type->regions[*idx];
> +		r_nid = memblock_get_region_node(r);
>  
>  		if (PFN_UP(r->base) >= PFN_DOWN(r->base + r->size))
>  			continue;
> -		if (nid == MAX_NUMNODES || nid == r->nid)
> +		if (nid == MAX_NUMNODES || nid == r_nid)
>  			break;
>  	}
>  	if (*idx >= type->cnt) {
> @@ -1226,7 +1228,7 @@ void __init_memblock __next_mem_pfn_range(int *idx, int nid,
>  	if (out_end_pfn)
>  		*out_end_pfn = PFN_DOWN(r->base + r->size);
>  	if (out_nid)
> -		*out_nid = r->nid;
> +		*out_nid = r_nid;
>  }
>  
>  /**
> @@ -1810,7 +1812,7 @@ int __init_memblock memblock_search_pfn_nid(unsigned long pfn,
>  	*start_pfn = PFN_DOWN(type->regions[mid].base);
>  	*end_pfn = PFN_DOWN(type->regions[mid].base + type->regions[mid].size);
>  
> -	return type->regions[mid].nid;
> +	return memblock_get_region_node(&type->regions[mid]);
>  }
>  #endif
>  
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 69827d4fa052..0d012eda1694 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -7208,7 +7208,7 @@ static void __init find_zone_movable_pfns_for_nodes(void)
>  			if (!memblock_is_hotpluggable(r))
>  				continue;
>  
> -			nid = r->nid;
> +			nid = memblock_get_region_node(r);
>  
>  			usable_startpfn = PFN_DOWN(r->base);
>  			zone_movable_pfn[nid] = zone_movable_pfn[nid] ?
> @@ -7229,7 +7229,7 @@ static void __init find_zone_movable_pfns_for_nodes(void)
>  			if (memblock_is_mirror(r))
>  				continue;
>  
> -			nid = r->nid;
> +			nid = memblock_get_region_node(r);
>  
>  			usable_startpfn = memblock_region_memory_base_pfn(r);

Looks good to me.

Reviewed-by: Baoquan He <[email-masked]>