linux-kernel - Re: [RESEND] x86/numa: move setting parsed numa node to num_add

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Date:   Mon, 11 Dec 2017 20:59:29 +0800
From:   zhong jiang <zhongjiang@...wei.com>
To:     Michal Hocko <mhocko@...nel.org>
CC:     <iamjoonsoo.kim@....com>, <mgorman@...hsingularity.net>,
        <minchan@...nel.org>, <vbabka@...e.cz>,
        <akpm@...ux-foundation.org>, <linux-kernel@...r.kernel.org>,
        <linux-mm@...ck.org>
Subject: Re: [RESEND] x86/numa: move setting parsed numa node to num_add_memblk

On 2017/12/11 20:03, Michal Hocko wrote:
> On Fri 01-12-17 18:13:52, zhong jiang wrote:
>> The acpi table are very much like user input. it is likely to
>> introduce some unreasonable node in some architecture. but
>> they do not ingore the node and bail out in time. it will result
>> in unnecessary print.
>> e.g  x86:  start is equal to end is a unreasonable node.
>> numa_blk_memblk will fails but return 0.
>>
>> meanwhile, Arm64 node will double set it to "numa_node_parsed"
>> after NUMA adds a memblk successfully.  but X86 is not. because
>> numa_add_memblk is not set in X86.
> I am sorry but I still fail to understand wht the actual problem is.
> You said that x86 will print a message. Alright at least you know that
> the platform provides a nonsense ACPI/SRAT? tables and you can complain.
> But does the kernel misbehave? In what way?
  From the view of  the following code , we should expect that the node is reasonable.
  otherwise, if we only want to complain,  it should bail out in time after printing the
  unreasonable message.

          node_set(node, numa_nodes_parsed);

        pr_info("SRAT: Node %u PXM %u [mem %#010Lx-%#010Lx]%s%s\n",
                node, pxm,
                (unsigned long long) start, (unsigned long long) end - 1,
                hotpluggable ? " hotplug" : "",
                ma->flags & ACPI_SRAT_MEM_NON_VOLATILE ? " non-volatile" : "");

        /* Mark hotplug range in memblock. */
        if (hotpluggable && memblock_mark_hotplug(start, ma->length))
                pr_warn("SRAT: Failed to mark hotplug range [mem %#010Lx-%#010Lx] in memblock\n",
                        (unsigned long long)start, (unsigned long long)end - 1);

        max_possible_pfn = max(max_possible_pfn, PFN_UP(end - 1));

        return 0;
out_err_bad_srat:
        bad_srat();

 In addition.  Arm64  will double set node to numa_nodes_parsed after add a memblk
successfully.  Because numa_add_memblk will perform node_set(*, *).

         if (numa_add_memblk(node, start, end) < 0) {
                pr_err("SRAT: Failed to add memblk to node %u [mem %#010Lx-%#010Lx]\n",
                       node, (unsigned long long) start,
                       (unsigned long long) end - 1);
                goto out_err_bad_srat;
        }

        node_set(node, numa_nodes_parsed);

Thanks
zhong jiang
>> In view of the above problems. I think it need a better improvement.
>> we add a check here for bypassing the invalid memblk node.
>>
>> Signed-off-by: zhong jiang <zhongjiang@...wei.com>
>> ---
>>  arch/x86/mm/amdtopology.c | 1 -
>>  arch/x86/mm/numa.c        | 3 ++-
>>  drivers/acpi/numa.c       | 5 ++++-
>>  3 files changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/x86/mm/amdtopology.c b/arch/x86/mm/amdtopology.c
>> index 91f501b..7657042 100644
>> --- a/arch/x86/mm/amdtopology.c
>> +++ b/arch/x86/mm/amdtopology.c
>> @@ -151,7 +151,6 @@ int __init amd_numa_init(void)
>>  
>>  		prevbase = base;
>>  		numa_add_memblk(nodeid, base, limit);
>> -		node_set(nodeid, numa_nodes_parsed);
>>  	}
>>  
>>  	if (!nodes_weight(numa_nodes_parsed))
>> diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
>> index 25504d5..8f87f26 100644
>> --- a/arch/x86/mm/numa.c
>> +++ b/arch/x86/mm/numa.c
>> @@ -150,6 +150,8 @@ static int __init numa_add_memblk_to(int nid, u64 start, u64 end,
>>  	mi->blk[mi->nr_blks].end = end;
>>  	mi->blk[mi->nr_blks].nid = nid;
>>  	mi->nr_blks++;
>> +
>> +	node_set(nid, numa_nodes_parsed);
>>  	return 0;
>>  }
>>  
>> @@ -693,7 +695,6 @@ static int __init dummy_numa_init(void)
>>  	printk(KERN_INFO "Faking a node at [mem %#018Lx-%#018Lx]\n",
>>  	       0LLU, PFN_PHYS(max_pfn) - 1);
>>  
>> -	node_set(0, numa_nodes_parsed);
>>  	numa_add_memblk(0, 0, PFN_PHYS(max_pfn));
>>  
>>  	return 0;
>> diff --git a/drivers/acpi/numa.c b/drivers/acpi/numa.c
>> index 917f1cc..f2e33cb 100644
>> --- a/drivers/acpi/numa.c
>> +++ b/drivers/acpi/numa.c
>> @@ -294,7 +294,9 @@ void __init acpi_numa_slit_init(struct acpi_table_slit *slit)
>>  		goto out_err_bad_srat;
>>  	}
>>  
>> -	node_set(node, numa_nodes_parsed);
>> +	/* some architecture is likely to ignore a unreasonable node */
>> +	if (!node_isset(node, numa_nodes_parsed))
>> +		goto out;
>>  
>>  	pr_info("SRAT: Node %u PXM %u [mem %#010Lx-%#010Lx]%s%s\n",
>>  		node, pxm,
>> @@ -309,6 +311,7 @@ void __init acpi_numa_slit_init(struct acpi_table_slit *slit)
>>  
>>  	max_possible_pfn = max(max_possible_pfn, PFN_UP(end - 1));
>>  
>> +out:
>>  	return 0;
>>  out_err_bad_srat:
>>  	bad_srat();
>> -- 
>> 1.8.3.1