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In-Reply-To: <20181206082806.GB1286@dhcp22.suse.cz>
From:   Pingfan Liu <kernelfans@gmail.com>
Date:   Thu, 6 Dec 2018 18:03:53 +0800
Message-ID: <CAFgQCTsMdQSRFruZRGBuo30TjfiQ=sbrf9kUJAGgwN6uw+LsBw@mail.gmail.com>
Subject: Re: [PATCH] mm/alloc: fallback to first node if the wanted node offline
To:     mhocko@kernel.org
Cc:     Vlastimil Babka <vbabka@suse.cz>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>
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Sender: linux-kernel-owner@vger.kernel.org
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[...]
> THanks for pointing this out. It made my life easier. So It think the
> bug is that we call init_memory_less_node from this path. I suspect
> numa_register_memblks is the right place to do this. So I admit I
> am not 100% sure but could you give this a try please?
>
Sure.

> diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
> index 1308f5408bf7..4575ae4d5449 100644
> --- a/arch/x86/mm/numa.c
> +++ b/arch/x86/mm/numa.c
> @@ -527,6 +527,19 @@ static void __init numa_clear_kernel_node_hotplug(void)
>         }
>  }
>
> +static void __init init_memory_less_node(int nid)
> +{
> +       unsigned long zones_size[MAX_NR_ZONES] = {0};
> +       unsigned long zholes_size[MAX_NR_ZONES] = {0};
> +
> +       free_area_init_node(nid, zones_size, 0, zholes_size);
> +
> +       /*
> +        * All zonelists will be built later in start_kernel() after per cpu
> +        * areas are initialized.
> +        */
> +}
> +
>  static int __init numa_register_memblks(struct numa_meminfo *mi)
>  {
>         unsigned long uninitialized_var(pfn_align);
> @@ -592,6 +605,8 @@ static int __init numa_register_memblks(struct numa_meminfo *mi)
>                         continue;
>
>                 alloc_node_data(nid);
> +               if (!end)
> +                       init_memory_less_node(nid);
>         }
>
>         /* Dump memblock with node info and return. */
> @@ -721,21 +736,6 @@ void __init x86_numa_init(void)
>         numa_init(dummy_numa_init);
>  }
>
> -static void __init init_memory_less_node(int nid)
> -{
> -       unsigned long zones_size[MAX_NR_ZONES] = {0};
> -       unsigned long zholes_size[MAX_NR_ZONES] = {0};
> -
> -       /* Allocate and initialize node data. Memory-less node is now online.*/
> -       alloc_node_data(nid);
> -       free_area_init_node(nid, zones_size, 0, zholes_size);
> -
> -       /*
> -        * All zonelists will be built later in start_kernel() after per cpu
> -        * areas are initialized.
> -        */
> -}
> -
>  /*
>   * Setup early cpu_to_node.
>   *
> @@ -763,9 +763,6 @@ void __init init_cpu_to_node(void)
>                 if (node == NUMA_NO_NODE)
>                         continue;
>
> -               if (!node_online(node))
> -                       init_memory_less_node(node);
> -
>                 numa_set_node(cpu, node);
>         }
>  }
> --
Which commit is this patch applied on? I can not apply it on latest linux tree.

Thanks,
Pingfan