linux-kernel - Re: [Patch 003/005](memory hotplug) make alloc_bootmem

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Message-ID: <20080616103231.GF17016@shadowen.org>
Date:	Mon, 16 Jun 2008 11:32:31 +0100
From:	Andy Whitcroft <apw@...dowen.org>
To:	Yasunori Goto <y-goto@...fujitsu.com>
Cc:	Badari Pulavarty <pbadari@...ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel ML <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>, Yinghai Lu <yhlu.kernel@...il.com>
Subject: Re: [Patch 003/005](memory hotplug) make alloc_bootmem_section()

On Mon, Apr 07, 2008 at 09:47:29PM +0900, Yasunori Goto wrote:
> alloc_bootmem_section() can allocate specified section's area.
> This is used for usemap to keep same section with pgdat by later patch.
> 
> Signed-off-by: Yasunori Goto <y-goto@...fujitsu.com>
> 
> ---
>  include/linux/bootmem.h |    2 ++
>  mm/bootmem.c            |   31 +++++++++++++++++++++++++++++++
>  2 files changed, 33 insertions(+)
> 
> Index: current/include/linux/bootmem.h
> ===================================================================
> --- current.orig/include/linux/bootmem.h	2008-04-07 19:18:44.000000000 +0900
> +++ current/include/linux/bootmem.h	2008-04-07 19:30:08.000000000 +0900
> @@ -101,6 +101,8 @@
>  extern void free_bootmem_node(pg_data_t *pgdat,
>  			      unsigned long addr,
>  			      unsigned long size);
> +extern void *alloc_bootmem_section(unsigned long size,
> +				   unsigned long section_nr);
>  
>  #ifndef CONFIG_HAVE_ARCH_BOOTMEM_NODE
>  #define alloc_bootmem_node(pgdat, x) \
> Index: current/mm/bootmem.c
> ===================================================================
> --- current.orig/mm/bootmem.c	2008-04-07 19:18:44.000000000 +0900
> +++ current/mm/bootmem.c	2008-04-07 19:30:08.000000000 +0900
> @@ -540,6 +540,37 @@
>  	return __alloc_bootmem(size, align, goal);
>  }
>  
> +#ifdef CONFIG_SPARSEMEM
> +void * __init alloc_bootmem_section(unsigned long size,
> +				    unsigned long section_nr)
> +{
> +	void *ptr;
> +	unsigned long limit, goal, start_nr, end_nr, pfn;
> +	struct pglist_data *pgdat;
> +
> +	pfn = section_nr_to_pfn(section_nr);
> +	goal = PFN_PHYS(pfn);
> +	limit = PFN_PHYS(section_nr_to_pfn(section_nr + 1)) - 1;
> +	pgdat = NODE_DATA(early_pfn_to_nid(pfn));
> +	ptr = __alloc_bootmem_core(pgdat->bdata, size, SMP_CACHE_BYTES, goal,
> +				   limit);
> +
> +	if (!ptr)
> +		return NULL;
> +
This also indicates a failure allocating within the section, and yet we
do not report it here.

> +	start_nr = pfn_to_section_nr(PFN_DOWN(__pa(ptr)));
> +	end_nr = pfn_to_section_nr(PFN_DOWN(__pa(ptr) + size));
> +	if (start_nr != section_nr || end_nr != section_nr) {
> +		printk(KERN_WARNING "alloc_bootmem failed on section %ld.\n",
> +		       section_nr);
> +		free_bootmem_core(pgdat->bdata, __pa(ptr), size);

But we do here.  I think we should report both if this is worth
reporting.

> +		ptr = NULL;
> +	}
> +
> +	return ptr;
> +}
> +#endif
> +
>  #ifndef ARCH_LOW_ADDRESS_LIMIT
>  #define ARCH_LOW_ADDRESS_LIMIT	0xffffffffUL
>  #endif

-apw
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