Re: [RFC PATCH]: ACPI: Automatically online hot-added memory

[Alex Chiang <achiang@hp.com>]

I think if you're going to poke into drivers/base/memory.c we
should let the -mm guys know that you're creating a new
interface.

The ACPI part looks fine to me.

cc added.

/ac

* Prarit Bhargava <prarit@redhat.com>:
> New sockets have on-die memory controllers.  This means that in certain
> HW configurations the memory behind the socket comes and goes as the socket
> is physically enabled and disabled.
> 
> Since the cpu bringup code does on node memory allocations, the memory on the
> added socket must be onlined first.
> 
> Add a .config option to automatically online hot added memory, and enable it
> in the acpi memory add path.
> 
> Signed-off-by: Prarit Bhargava <prarit@redhat.com>
> 
> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
> index 93d2c79..dece6bd 100644
> --- a/drivers/acpi/Kconfig
> +++ b/drivers/acpi/Kconfig
> @@ -350,6 +350,14 @@ config ACPI_HOTPLUG_MEMORY
>  	  To compile this driver as a module, choose M here:
>  	  the module will be called acpi_memhotplug.
>  
> +config ACPI_HOTPLUG_MEMORY_AUTO_ONLINE
> +	bool "Automatically online hotplugged memory"
> +	depends on ACPI_HOTPLUG_MEMORY
> +	default n
> +	help
> +	  This forces memory that is brought into service by ACPI
> +	  to be automatically onlined.
> +
>  config ACPI_SBS
>  	tristate "Smart Battery System"
>  	depends on X86
> diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
> index 3597d73..9814c50 100644
> --- a/drivers/acpi/acpi_memhotplug.c
> +++ b/drivers/acpi/acpi_memhotplug.c
> @@ -30,6 +30,7 @@
>  #include <linux/init.h>
>  #include <linux/types.h>
>  #include <linux/memory_hotplug.h>
> +#include <linux/memory.h>
>  #include <acpi/acpi_drivers.h>
>  
>  #define ACPI_MEMORY_DEVICE_CLASS		"memory"
> @@ -252,6 +253,19 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
>  		result = add_memory(node, info->start_addr, info->length);
>  		if (result)
>  			continue;
> +#ifdef CONFIG_ACPI_HOTPLUG_MEMORY_AUTO_ONLINE
> +		/*
> +		 * New processors require memory to be online before cpus.
> +		 * No notifications are required here as "we" are the only
> +		 * ones who know about the new memory right now.
> +		 */
> +		result = online_pages(info->start_addr >> PAGE_SHIFT,
> +				      info->length >> PAGE_SHIFT);
> +		if (!result)
> +			set_memory_state(info->start_addr, MEM_ONLINE);
> +		else
> +			printk("Memory online failed.\n");
> +#endif
>  		info->enabled = 1;
>  		num_enabled++;
>  	}
> diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> index 2f86915..fb465d5 100644
> --- a/drivers/base/memory.c
> +++ b/drivers/base/memory.c
> @@ -510,6 +510,20 @@ int remove_memory_block(unsigned long node_id, struct mem_section *section,
>  }
>  
>  /*
> + * need an interface for the VM to mark sections on and offline when hot-adding
> + * memory.
> + */
> +void set_memory_state(unsigned long addr, unsigned long state)
> +{
> +	struct mem_section *section;
> +	struct memory_block *mem;
> +
> +	section = __pfn_to_section(addr >> PAGE_SHIFT);
> +	mem = find_memory_block(section);
> +	mem->state = state;
> +}
> +
> +/*
>   * need an interface for the VM to add new memory regions,
>   * but without onlining it.
>   */
> diff --git a/include/linux/memory.h b/include/linux/memory.h
> index 1adfe77..5d8d78c 100644
> --- a/include/linux/memory.h
> +++ b/include/linux/memory.h
> @@ -112,6 +112,7 @@ extern int remove_memory_block(unsigned long, struct mem_section *, int);
>  extern int memory_notify(unsigned long val, void *v);
>  extern int memory_isolate_notify(unsigned long val, void *v);
>  extern struct memory_block *find_memory_block(struct mem_section *);
> +extern void set_memory_state(unsigned long, unsigned long);
>  #define CONFIG_MEM_BLOCK_SIZE	(PAGES_PER_SECTION<<PAGE_SHIFT)
>  enum mem_add_context { BOOT, HOTPLUG };
>  #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
> --
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