Re: [PART5 Patch 1/5] page_alloc: add kernelcore_max_addr

[Randy Dunlap <rdunlap@infradead.org>]

On 10/31/12 02:21, Wen Congyang wrote:
> From: Lai Jiangshan <laijs@cn.fujitsu.com>
> 
> Current ZONE_MOVABLE (kernelcore=) setting policy with boot option doesn't meet
> our requirement. We need something like kernelcore_max_addr=XX boot option
> to limit the kernelcore upper address.
> 
> The memory with higher address will be migratable(movable) and they
> are easier to be offline(always ready to be offline when the system don't require
> so much memory).
> 
> It makes things easy when we dynamic hot-add/remove memory, make better
> utilities of memories, and helps for THP.
> 
> All kernelcore_max_addr=, kernelcore= and movablecore= can be safely specified
> at the same time(or any 2 of them).
> 
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
> ---
>  Documentation/kernel-parameters.txt |  9 +++++++++
>  mm/page_alloc.c                     | 29 ++++++++++++++++++++++++++++-
>  2 files changed, 37 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index 9776f06..2b72ffb 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -1223,6 +1223,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>  			use the HighMem zone if it exists, and the Normal
>  			zone if it does not.
>  
> +	kernelcore_max_addr=nn[KMG]	[KNL,X86,IA-64,PPC] This parameter
> +			is the same effect as kernelcore parameter, except it
> +			specifies the up physical address of memory range

			              upper (or maximum)

> +			usable by the kernel for non-movable allocations.
> +			If both kernelcore and kernelcore_max_addr are
> +			specified, this requested's priority is higher than

			specified, this parameter has a higher priority than
			the kernelcore parameter.

> +			kernelcore's.
> +			See the kernelcore parameter.
> +
>  	kgdbdbgp=	[KGDB,HW] kgdb over EHCI usb debug port.
>  			Format: <Controller#>[,poll interval]
>  			The controller # is the number of the ehci usb debug
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 5b74de6..9c35fe5 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -200,6 +200,7 @@ static unsigned long __meminitdata dma_reserve;
>  #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
>  static unsigned long __meminitdata arch_zone_lowest_possible_pfn[MAX_NR_ZONES];
>  static unsigned long __meminitdata arch_zone_highest_possible_pfn[MAX_NR_ZONES];
> +static unsigned long __initdata required_kernelcore_max_pfn;
>  static unsigned long __initdata required_kernelcore;
>  static unsigned long __initdata required_movablecore;
>  static unsigned long __meminitdata zone_movable_pfn[MAX_NUMNODES];
> @@ -4715,6 +4716,7 @@ static void __init find_zone_movable_pfns_for_nodes(void)
>  {
>  	int i, nid;
>  	unsigned long usable_startpfn;
> +	unsigned long kernelcore_max_pfn;
>  	unsigned long kernelcore_node, kernelcore_remaining;
>  	/* save the state before borrow the nodemask */
>  	nodemask_t saved_node_state = node_states[N_HIGH_MEMORY];
> @@ -4743,6 +4745,9 @@ static void __init find_zone_movable_pfns_for_nodes(void)
>  		required_kernelcore = max(required_kernelcore, corepages);
>  	}
>  
> +	if (required_kernelcore_max_pfn && !required_kernelcore)
> +		required_kernelcore = totalpages;
> +
>  	/* If kernelcore was not specified, there is no ZONE_MOVABLE */
>  	if (!required_kernelcore)
>  		goto out;
> @@ -4751,6 +4756,12 @@ static void __init find_zone_movable_pfns_for_nodes(void)
>  	find_usable_zone_for_movable();
>  	usable_startpfn = arch_zone_lowest_possible_pfn[movable_zone];
>  
> +	if (required_kernelcore_max_pfn)
> +		kernelcore_max_pfn = required_kernelcore_max_pfn;
> +	else
> +		kernelcore_max_pfn = ULONG_MAX >> PAGE_SHIFT;
> +	kernelcore_max_pfn = max(kernelcore_max_pfn, usable_startpfn);
> +
>  restart:
>  	/* Spread kernelcore memory as evenly as possible throughout nodes */
>  	kernelcore_node = required_kernelcore / usable_nodes;
> @@ -4777,8 +4788,12 @@ restart:
>  			unsigned long size_pages;
>  
>  			start_pfn = max(start_pfn, zone_movable_pfn[nid]);
> -			if (start_pfn >= end_pfn)
> +			end_pfn = min(kernelcore_max_pfn, end_pfn);
> +			if (start_pfn >= end_pfn) {
> +				if (!zone_movable_pfn[nid])
> +					zone_movable_pfn[nid] = start_pfn;
>  				continue;
> +			}
>  
>  			/* Account for what is only usable for kernelcore */
>  			if (start_pfn < usable_startpfn) {
> @@ -4965,6 +4980,18 @@ static int __init cmdline_parse_core(char *p, unsigned long *core)
>  	return 0;
>  }
>  
> +#ifdef CONFIG_MOVABLE_NODE
> +/*
> + * kernelcore_max_addr=addr sets the up physical address of memory range

                                        upper

> + * for use for allocations that cannot be reclaimed or migrated.
> + */
> +static int __init cmdline_parse_kernelcore_max_addr(char *p)
> +{
> +	return cmdline_parse_core(p, &required_kernelcore_max_pfn);
> +}
> +early_param("kernelcore_max_addr", cmdline_parse_kernelcore_max_addr);
> +#endif
> +
>  /*
>   * kernelcore=size sets the amount of memory for use for allocations that
>   * cannot be reclaimed or migrated.
> 


-- 
~Randy

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