linux-kernel - Re: [PATCH v1 09/12] ACPI: memhotplug: use a single static memory group for a single memory device

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Date:   Tue, 8 Jun 2021 14:20:40 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     David Hildenbrand <david@...hat.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Marek Kedzierski <mkedzier@...hat.com>,
        Hui Zhu <teawater@...il.com>,
        Pankaj Gupta <pankaj.gupta.linux@...il.com>,
        Wei Yang <richard.weiyang@...ux.alibaba.com>,
        Oscar Salvador <osalvador@...e.de>,
        Michal Hocko <mhocko@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Mike Rapoport <rppt@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        virtualization@...ts.linux-foundation.org,
        Linux Memory Management List <linux-mm@...ck.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>
Subject: Re: [PATCH v1 09/12] ACPI: memhotplug: use a single static memory
 group for a single memory device

On Mon, Jun 7, 2021 at 9:55 PM David Hildenbrand <david@...hat.com> wrote:
>
> Let's group all memory we add for a single memory device - we want a
> single node for that (which also seems to be the sane thing to do).
>
> We won't care for now about memory that was already added to the system
> (e.g., via e820) -- usually *all* memory of a memory device was already
> added and we'll fail acpi_memory_enable_device().
>
> Signed-off-by: David Hildenbrand <david@...hat.com>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

> ---
>  drivers/acpi/acpi_memhotplug.c | 35 +++++++++++++++++++++++++++++-----
>  1 file changed, 30 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
> index eb4faf7c5cad..0c7b062c0e5d 100644
> --- a/drivers/acpi/acpi_memhotplug.c
> +++ b/drivers/acpi/acpi_memhotplug.c
> @@ -54,6 +54,7 @@ struct acpi_memory_info {
>  struct acpi_memory_device {
>         struct acpi_device *device;
>         struct list_head res_list;
> +       int mgid;
>  };
>
>  static acpi_status
> @@ -171,10 +172,31 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
>         acpi_handle handle = mem_device->device->handle;
>         int result, num_enabled = 0;
>         struct acpi_memory_info *info;
> -       mhp_t mhp_flags = MHP_NONE;
> -       int node;
> +       mhp_t mhp_flags = MHP_NID_IS_MGID;
> +       u64 total_length = 0;
> +       int node, mgid;
>
>         node = acpi_get_node(handle);
> +
> +       list_for_each_entry(info, &mem_device->res_list, list) {
> +               if (!info->length)
> +                       continue;
> +               /* We want a single node for the whole memory group */
> +               if (node < 0)
> +                       node = memory_add_physaddr_to_nid(info->start_addr);
> +               total_length += info->length;
> +       }
> +
> +       if (!total_length) {
> +               dev_err(&mem_device->device->dev, "device is empty\n");
> +               return -EINVAL;
> +       }
> +
> +       mgid = register_static_memory_group(node, PFN_UP(total_length));
> +       if (mgid < 0)
> +               return mgid;
> +       mem_device->mgid = mgid;
> +
>         /*
>          * Tell the VM there is more memory here...
>          * Note: Assume that this function returns zero on success
> @@ -188,12 +210,10 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
>                  */
>                 if (!info->length)
>                         continue;
> -               if (node < 0)
> -                       node = memory_add_physaddr_to_nid(info->start_addr);
>
>                 if (mhp_supports_memmap_on_memory(info->length))
>                         mhp_flags |= MHP_MEMMAP_ON_MEMORY;
> -               result = __add_memory(node, info->start_addr, info->length,
> +               result = __add_memory(mgid, info->start_addr, info->length,
>                                       mhp_flags);
>
>                 /*
> @@ -253,6 +273,10 @@ static void acpi_memory_device_free(struct acpi_memory_device *mem_device)
>         if (!mem_device)
>                 return;
>
> +       /* In case we succeeded adding *some* memory, unregistering fails. */
> +       if (mem_device->mgid >= 0)
> +               unregister_memory_group(mem_device->mgid);
> +
>         acpi_memory_free_device_resources(mem_device);
>         mem_device->device->driver_data = NULL;
>         kfree(mem_device);
> @@ -273,6 +297,7 @@ static int acpi_memory_device_add(struct acpi_device *device,
>
>         INIT_LIST_HEAD(&mem_device->res_list);
>         mem_device->device = device;
> +       mem_device->mgid = -1;
>         sprintf(acpi_device_name(device), "%s", ACPI_MEMORY_DEVICE_NAME);
>         sprintf(acpi_device_class(device), "%s", ACPI_MEMORY_DEVICE_CLASS);
>         device->driver_data = mem_device;
> --
> 2.31.1
>