On 2013/5/19 7:34, Rafael J. Wysocki wrote:

> From: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
> 
> As indicated by comments in mm/memory_hotplug.c:remove_memory(),
> if CONFIG_MEMCG is set, it may not be possible to offline all of the
> memory blocks held by one module (FRU) in one pass (because one of
> them may be used by the others to store page cgroup in that case
> and that block has to be offlined before the other ones).
> 
> To handle that arguably corner case, add a second pass of companion
> device offlining to acpi_scan_hot_remove() and make it ignore errors
> returned in the first pass (and make it skip the second pass if the
> first one is successful).
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
> ---
>  drivers/acpi/scan.c |   67 
> ++++++++++++++++++++++++++++++++++++++--------------
>  1 file changed, 50 insertions(+), 17 deletions(-)
> 
> Index: linux-pm/drivers/acpi/scan.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/scan.c
> +++ linux-pm/drivers/acpi/scan.c
> @@ -131,6 +131,7 @@ static acpi_status acpi_bus_offline_comp
>  {
>       struct acpi_device *device = NULL;
>       struct acpi_device_physical_node *pn;
> +     bool second_pass = (bool)data;
>       acpi_status status = AE_OK;
>  
>       if (acpi_bus_get_device(handle, &device))
> @@ -141,15 +142,26 @@ static acpi_status acpi_bus_offline_comp
>       list_for_each_entry(pn, &device->physical_node_list, node) {
>               int ret;
>  
> +             if (second_pass) {
> +                     /* Skip devices offlined by the first pass. */
> +                     if (pn->put_online)

should it be "if (!pn->put_online)" ?

Thanks
Xishi Qiu

> +                             continue;
> +             } else {
> +                     pn->put_online = false;
> +             }
>               ret = device_offline(pn->dev);
>               if (acpi_force_hot_remove)
>                       continue;
>  
> -             if (ret < 0) {
> -                     status = AE_ERROR;
> -                     break;
> +             if (ret >= 0) {
> +                     pn->put_online = !ret;
> +             } else {
> +                     *ret_p = pn->dev;
> +                     if (second_pass) {
> +                             status = AE_ERROR;
> +                             break;
> +                     }
>               }
> -             pn->put_online = !ret;
>       }
>  
>       mutex_unlock(&device->physical_node_lock);



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