Re: [PATCH] mm: hugetlb: rework hugetlb cmdline parsing

[Christophe Leroy]

Le 16/06/2022 à 09:18, Muchun Song a écrit :
> I often get lost in the logic interleaved between numerous global
> variables for parsing cmdline.  It is not easy to be maintained.
> This patch aims to rework cmdline parsing to simlify the code and
> make the code more readable.

This patch is quite big.

Can you explain in the commit description in more details what are the 
changes performed by this patch ?

Otherwise I have absolutely no idea of what to review or what to test.

Thanks
Christophe

> 
> Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> ---
>   include/linux/hugetlb.h |   1 -
>   mm/hugetlb.c            | 499 ++++++++++++++++++++----------------------------
>   2 files changed, 206 insertions(+), 294 deletions(-)
> 
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index 642a39016f9a..aab2ef3a054d 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -636,7 +636,6 @@ struct hstate {
>   	unsigned long nr_overcommit_huge_pages;
>   	struct list_head hugepage_activelist;
>   	struct list_head hugepage_freelists[MAX_NUMNODES];
> -	unsigned int max_huge_pages_node[MAX_NUMNODES];
>   	unsigned int nr_huge_pages_node[MAX_NUMNODES];
>   	unsigned int free_huge_pages_node[MAX_NUMNODES];
>   	unsigned int surplus_huge_pages_node[MAX_NUMNODES];
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 98492733cc64..0d3c1ae58107 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -37,6 +37,7 @@
>   #include <asm/page.h>
>   #include <asm/pgalloc.h>
>   #include <asm/tlb.h>
> +#include <asm/setup.h>
>   
>   #include <linux/io.h>
>   #include <linux/hugetlb.h>
> @@ -47,7 +48,7 @@
>   #include "hugetlb_vmemmap.h"
>   
>   int hugetlb_max_hstate __read_mostly;
> -unsigned int default_hstate_idx;
> +unsigned int default_hstate_idx = HUGE_MAX_HSTATE;
>   struct hstate hstates[HUGE_MAX_HSTATE];
>   
>   #ifdef CONFIG_CMA
> @@ -68,13 +69,6 @@ static unsigned long hugetlb_cma_size __initdata;
>   
>   __initdata LIST_HEAD(huge_boot_pages);
>   
> -/* for command line parsing */
> -static struct hstate * __initdata parsed_hstate;
> -static unsigned long __initdata default_hstate_max_huge_pages;
> -static bool __initdata parsed_valid_hugepagesz = true;
> -static bool __initdata parsed_default_hugepagesz;
> -static unsigned int default_hugepages_in_node[MAX_NUMNODES] __initdata;
> -
>   /*
>    * Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages,
>    * free_huge_pages, and surplus_huge_pages.
> @@ -3026,6 +3020,146 @@ int __alloc_bootmem_huge_page(struct hstate *h, int nid)
>   	return 1;
>   }
>   
> +struct hugetlb_one_arg {
> +	unsigned long hugepagesz;
> +	unsigned long hugepages;
> +	unsigned long hugepages_node[MAX_NUMNODES];
> +};
> +
> +struct hugetlb_args {
> +	unsigned int		nr_arg;
> +	struct hugetlb_one_arg	args[HUGE_MAX_HSTATE];
> +};
> +
> +static struct hugetlb_args hugetlb_args __initdata;
> +
> +static unsigned long __init hugetlb_parse_hugepagesz(const char *param,
> +						     const char *val)
> +{
> +	unsigned long size;
> +
> +	size = memparse(val, NULL);
> +	if (!arch_hugetlb_valid_size(size)) {
> +		pr_err("HugeTLB: %s=%s is unsupported\n", param, val);
> +		return 0;
> +	}
> +	hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT);
> +	return size;
> +}
> +
> +static int __init hugetlb_process_arg(char *param, char *val,
> +				      const char *unused, void *priv)
> +{
> +	struct hugetlb_args *args = priv;
> +	struct hugetlb_one_arg *arg = &args->args[args->nr_arg];
> +
> +	if (!val)
> +		return 0;
> +
> +	if (!strcmp(param, "hugepagesz")) {
> +		unsigned long size = hugetlb_parse_hugepagesz(param, val);
> +
> +		/*
> +		 * "ULONG_MAX" means the next parameter "hugepages" should be
> +		 * ignored.
> +		 */
> +		size = size ? : ULONG_MAX;
> +
> +		/* Lookup "hugepagesz" whether if we have specified before. */
> +		if (size != ULONG_MAX) {
> +			int i;
> +
> +			for (i = 0; i < args->nr_arg; i++) {
> +				if (args->args[i].hugepagesz == size ||
> +				    (!args->args[i].hugepagesz && size == HPAGE_SIZE)) {
> +					pr_warn("HugeTLB: %s=%s is ignored\n", param, val);
> +					size = ULONG_MAX;
> +					break;
> +				}
> +			}
> +		}
> +		arg->hugepagesz = size;
> +	} else if (!strcmp(param, "default_hugepagesz")) {
> +		unsigned long size = hugetlb_parse_hugepagesz(param, val);
> +
> +		if (size == 0)
> +			return 0;
> +
> +		if (default_hstate_idx != HUGE_MAX_HSTATE) {
> +			pr_err("HugeTLB: %s=%s is ignored\n", param, val);
> +		} else {
> +			default_hstate_idx = hstate_index(size_to_hstate(size));
> +
> +			/*
> +			 * Update ->hugepagesz if the first "hugepages" is
> +			 * followed by "default_hugepagesz".
> +			 */
> +			if (args->args[0].hugepagesz == 0)
> +				args->args[0].hugepagesz = size;
> +		}
> +	} else if (!strcmp(param, "hugepages")) {
> +		int node;
> +		const char *p = val;
> +
> +		/*
> +		 * There are two cases which need to be ignored.
> +		 *
> +		 * 1) The previous "hugepagesz" is invalid.
> +		 * 2) Lack of "hugepagesz" which matches with "hugepages" except
> +		 *    the first "hugepages".
> +		 */
> +		if (arg->hugepagesz == ULONG_MAX ||
> +		    (arg->hugepagesz == 0 && args->nr_arg != 0)) {
> +			pr_warn("HugeTLB: %s=%s is ignored\n", param, val);
> +			return 0;
> +		}
> +
> +		while (*p) {
> +			int count = 0;
> +			unsigned long tmp;
> +
> +			if (sscanf(p, "%lu%n", &tmp, &count) != 1)
> +				goto invalid;
> +
> +			/* Parameter is node format */
> +			if (p[count] == ':') {
> +				if (!hugetlb_node_alloc_supported()) {
> +					pr_warn("HugeTLB: architecture can't support node specific alloc, ignoring!\n");
> +					return 0;
> +				}
> +				if (tmp >= MAX_NUMNODES || !node_online(tmp))
> +					goto invalid;
> +				node = array_index_nospec(tmp, MAX_NUMNODES);
> +				p += count + 1;
> +				/* Parse hugepages */
> +				if (sscanf(p, "%lu%n", &tmp, &count) != 1)
> +					goto invalid;
> +				arg->hugepages_node[node] = tmp;
> +				arg->hugepages += tmp;
> +				/* Go to parse next node*/
> +				if (p[count] == ',')
> +					p += count + 1;
> +				else
> +					break;
> +			} else {
> +				if (p != val)
> +					goto invalid;
> +				arg->hugepages = tmp;
> +				break;
> +			}
> +		}
> +		args->nr_arg++;
> +		return 0;
> +invalid:
> +		for_each_node(node)
> +			arg->hugepages_node[node] = 0;
> +		arg->hugepages = 0;
> +		pr_warn("HugeTLB: %s=%s is ignored\n", param, val);
> +	}
> +
> +	return 0;
> +}
> +
>   /*
>    * Put bootmem huge pages into the standard lists after mem_map is up.
>    * Note: This only applies to gigantic (order > MAX_ORDER) pages.
> @@ -3058,12 +3192,13 @@ static void __init gather_bootmem_prealloc(void)
>   		cond_resched();
>   	}
>   }
> -static void __init hugetlb_hstate_alloc_pages_onenode(struct hstate *h, int nid)
> +static void __init hugetlb_hstate_alloc_pages_onenode(struct hstate *h, int nid,
> +						      struct hugetlb_one_arg *arg)
>   {
>   	unsigned long i;
>   	char buf[32];
>   
> -	for (i = 0; i < h->max_huge_pages_node[nid]; ++i) {
> +	for (i = 0; i < arg->hugepages_node[nid]; ++i) {
>   		if (hstate_is_gigantic(h)) {
>   			if (!alloc_bootmem_huge_page(h, nid))
>   				break;
> @@ -3079,32 +3214,33 @@ static void __init hugetlb_hstate_alloc_pages_onenode(struct hstate *h, int nid)
>   		}
>   		cond_resched();
>   	}
> -	if (i == h->max_huge_pages_node[nid])
> +	h->max_huge_pages += i;
> +	if (i == arg->hugepages_node[nid])
>   		return;
>   
>   	string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32);
> -	pr_warn("HugeTLB: allocating %u of page size %s failed node%d.  Only allocated %lu hugepages.\n",
> -		h->max_huge_pages_node[nid], buf, nid, i);
> -	h->max_huge_pages -= (h->max_huge_pages_node[nid] - i);
> -	h->max_huge_pages_node[nid] = i;
> +	pr_warn("HugeTLB: allocating %lu of page size %s failed node%d.  Only allocated %lu hugepages.\n",
> +		arg->hugepages_node[nid], buf, nid, i);
>   }
>   
> -static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
> +static void __init hugetlb_hstate_alloc_pages(struct hstate *h,
> +					      struct hugetlb_one_arg *arg)
>   {
>   	unsigned long i;
> -	nodemask_t *node_alloc_noretry;
> +	nodemask_t node_alloc_noretry = NODE_MASK_NONE;
>   	bool node_specific_alloc = false;
>   
>   	/* skip gigantic hugepages allocation if hugetlb_cma enabled */
>   	if (hstate_is_gigantic(h) && hugetlb_cma_size) {
> +		h->max_huge_pages = arg->hugepages;
>   		pr_warn_once("HugeTLB: hugetlb_cma is enabled, skip boot time allocation\n");
>   		return;
>   	}
>   
>   	/* do node specific alloc */
>   	for_each_online_node(i) {
> -		if (h->max_huge_pages_node[i] > 0) {
> -			hugetlb_hstate_alloc_pages_onenode(h, i);
> +		if (arg->hugepages_node[i] > 0) {
> +			hugetlb_hstate_alloc_pages_onenode(h, i, arg);
>   			node_specific_alloc = true;
>   		}
>   	}
> @@ -3112,55 +3248,75 @@ static void __init hugetlb_hstate_alloc_pages(struct hstate *h)
>   	if (node_specific_alloc)
>   		return;
>   
> -	/* below will do all node balanced alloc */
> -	if (!hstate_is_gigantic(h)) {
> -		/*
> -		 * Bit mask controlling how hard we retry per-node allocations.
> -		 * Ignore errors as lower level routines can deal with
> -		 * node_alloc_noretry == NULL.  If this kmalloc fails at boot
> -		 * time, we are likely in bigger trouble.
> -		 */
> -		node_alloc_noretry = kmalloc(sizeof(*node_alloc_noretry),
> -						GFP_KERNEL);
> -	} else {
> -		/* allocations done at boot time */
> -		node_alloc_noretry = NULL;
> -	}
> -
> -	/* bit mask controlling how hard we retry per-node allocations */
> -	if (node_alloc_noretry)
> -		nodes_clear(*node_alloc_noretry);
> -
> -	for (i = 0; i < h->max_huge_pages; ++i) {
> +	for (i = 0; i < arg->hugepages; ++i) {
>   		if (hstate_is_gigantic(h)) {
>   			if (!alloc_bootmem_huge_page(h, NUMA_NO_NODE))
>   				break;
>   		} else if (!alloc_pool_huge_page(h,
>   					 &node_states[N_MEMORY],
> -					 node_alloc_noretry))
> +					 &node_alloc_noretry))
>   			break;
>   		cond_resched();
>   	}
> -	if (i < h->max_huge_pages) {
> +	h->max_huge_pages = i;
> +	if (i < arg->hugepages) {
>   		char buf[32];
>   
>   		string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32);
>   		pr_warn("HugeTLB: allocating %lu of page size %s failed.  Only allocated %lu hugepages.\n",
> -			h->max_huge_pages, buf, i);
> -		h->max_huge_pages = i;
> +			arg->hugepages, buf, i);
> +	}
> +}
> +
> +static void __init hugetlb_prealloc(bool gigantic)
> +{
> +	int i;
> +
> +	for (i = 0; i < hugetlb_args.nr_arg; i++) {
> +		struct hstate *h;
> +		struct hugetlb_one_arg *arg;
> +
> +		arg = &hugetlb_args.args[i];
> +		if (arg->hugepagesz == 0) {
> +			arg->hugepagesz = HPAGE_SIZE;
> +			default_hstate_idx = hstate_index(size_to_hstate(HPAGE_SIZE));
> +		}
> +		h = size_to_hstate(arg->hugepagesz);
> +		if (hstate_is_gigantic(h) == gigantic)
> +			hugetlb_hstate_alloc_pages(h, arg);
>   	}
> -	kfree(node_alloc_noretry);
>   }
>   
> +static int __init hugetlb_cmdline_parse(char *s)
> +{
> +	static bool parsed __initdata;
> +	static char cmdline[COMMAND_LINE_SIZE] __initdata;
> +
> +	if (!hugepages_supported() || parsed)
> +		return 1;
> +	/*
> +	 * Make sure HPAGE_SIZE (HUGETLB_PAGE_ORDER) hstate exists.  Some
> +	 * architectures depend on setup being done here.
> +	 */
> +	hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
> +
> +	strscpy(cmdline, boot_command_line, COMMAND_LINE_SIZE);
> +	parse_args("HugeTLB options", cmdline, NULL, 0, 0, 0, &hugetlb_args,
> +		   hugetlb_process_arg);
> +	hugetlb_prealloc(true);
> +	parsed = true;
> +
> +	return 1;
> +}
> +__setup_param("hugepages", hugepages, hugetlb_cmdline_parse, 0);
> +__setup_param("hugepagesz", hugepagesz, hugetlb_cmdline_parse, 0);
> +__setup_param("default_hugepagesz", default_hugepagesz, hugetlb_cmdline_parse, 0);
> +
>   static void __init hugetlb_init_hstates(void)
>   {
>   	struct hstate *h, *h2;
>   
>   	for_each_hstate(h) {
> -		/* oversize hugepages were init'ed in early boot */
> -		if (!hstate_is_gigantic(h))
> -			hugetlb_hstate_alloc_pages(h);
> -
>   		/*
>   		 * Set demote order for each hstate.  Note that
>   		 * h->demote_order is initially 0.
> @@ -4027,48 +4183,11 @@ static int __init hugetlb_init(void)
>   	BUILD_BUG_ON(sizeof_field(struct page, private) * BITS_PER_BYTE <
>   			__NR_HPAGEFLAGS);
>   
> -	if (!hugepages_supported()) {
> -		if (hugetlb_max_hstate || default_hstate_max_huge_pages)
> -			pr_warn("HugeTLB: huge pages not supported, ignoring associated command-line parameters\n");
> +	if (!hugepages_supported())
>   		return 0;
> -	}
> -
> -	/*
> -	 * Make sure HPAGE_SIZE (HUGETLB_PAGE_ORDER) hstate exists.  Some
> -	 * architectures depend on setup being done here.
> -	 */
> -	hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
> -	if (!parsed_default_hugepagesz) {
> -		/*
> -		 * If we did not parse a default huge page size, set
> -		 * default_hstate_idx to HPAGE_SIZE hstate. And, if the
> -		 * number of huge pages for this default size was implicitly
> -		 * specified, set that here as well.
> -		 * Note that the implicit setting will overwrite an explicit
> -		 * setting.  A warning will be printed in this case.
> -		 */
> -		default_hstate_idx = hstate_index(size_to_hstate(HPAGE_SIZE));
> -		if (default_hstate_max_huge_pages) {
> -			if (default_hstate.max_huge_pages) {
> -				char buf[32];
> -
> -				string_get_size(huge_page_size(&default_hstate),
> -					1, STRING_UNITS_2, buf, 32);
> -				pr_warn("HugeTLB: Ignoring hugepages=%lu associated with %s page size\n",
> -					default_hstate.max_huge_pages, buf);
> -				pr_warn("HugeTLB: Using hugepages=%lu for number of default huge pages\n",
> -					default_hstate_max_huge_pages);
> -			}
> -			default_hstate.max_huge_pages =
> -				default_hstate_max_huge_pages;
> -
> -			for_each_online_node(i)
> -				default_hstate.max_huge_pages_node[i] =
> -					default_hugepages_in_node[i];
> -		}
> -	}
>   
>   	hugetlb_cma_check();
> +	hugetlb_prealloc(false);
>   	hugetlb_init_hstates();
>   	gather_bootmem_prealloc();
>   	report_hugepages();
> @@ -4121,8 +4240,6 @@ void __init hugetlb_add_hstate(unsigned int order)
>   	snprintf(h->name, HSTATE_NAME_LEN, "hugepages-%lukB",
>   					huge_page_size(h)/1024);
>   	hugetlb_vmemmap_init(h);
> -
> -	parsed_hstate = h;
>   }
>   
>   bool __init __weak hugetlb_node_alloc_supported(void)
> @@ -4130,210 +4247,6 @@ bool __init __weak hugetlb_node_alloc_supported(void)
>   	return true;
>   }
>   
> -static void __init hugepages_clear_pages_in_node(void)
> -{
> -	if (!hugetlb_max_hstate) {
> -		default_hstate_max_huge_pages = 0;
> -		memset(default_hugepages_in_node, 0,
> -			MAX_NUMNODES * sizeof(unsigned int));
> -	} else {
> -		parsed_hstate->max_huge_pages = 0;
> -		memset(parsed_hstate->max_huge_pages_node, 0,
> -			MAX_NUMNODES * sizeof(unsigned int));
> -	}
> -}
> -
> -/*
> - * hugepages command line processing
> - * hugepages normally follows a valid hugepagsz or default_hugepagsz
> - * specification.  If not, ignore the hugepages value.  hugepages can also
> - * be the first huge page command line  option in which case it implicitly
> - * specifies the number of huge pages for the default size.
> - */
> -static int __init hugepages_setup(char *s)
> -{
> -	unsigned long *mhp;
> -	static unsigned long *last_mhp;
> -	int node = NUMA_NO_NODE;
> -	int count;
> -	unsigned long tmp;
> -	char *p = s;
> -
> -	if (!parsed_valid_hugepagesz) {
> -		pr_warn("HugeTLB: hugepages=%s does not follow a valid hugepagesz, ignoring\n", s);
> -		parsed_valid_hugepagesz = true;
> -		return 1;
> -	}
> -
> -	/*
> -	 * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter
> -	 * yet, so this hugepages= parameter goes to the "default hstate".
> -	 * Otherwise, it goes with the previously parsed hugepagesz or
> -	 * default_hugepagesz.
> -	 */
> -	else if (!hugetlb_max_hstate)
> -		mhp = &default_hstate_max_huge_pages;
> -	else
> -		mhp = &parsed_hstate->max_huge_pages;
> -
> -	if (mhp == last_mhp) {
> -		pr_warn("HugeTLB: hugepages= specified twice without interleaving hugepagesz=, ignoring hugepages=%s\n", s);
> -		return 1;
> -	}
> -
> -	while (*p) {
> -		count = 0;
> -		if (sscanf(p, "%lu%n", &tmp, &count) != 1)
> -			goto invalid;
> -		/* Parameter is node format */
> -		if (p[count] == ':') {
> -			if (!hugetlb_node_alloc_supported()) {
> -				pr_warn("HugeTLB: architecture can't support node specific alloc, ignoring!\n");
> -				return 1;
> -			}
> -			if (tmp >= MAX_NUMNODES || !node_online(tmp))
> -				goto invalid;
> -			node = array_index_nospec(tmp, MAX_NUMNODES);
> -			p += count + 1;
> -			/* Parse hugepages */
> -			if (sscanf(p, "%lu%n", &tmp, &count) != 1)
> -				goto invalid;
> -			if (!hugetlb_max_hstate)
> -				default_hugepages_in_node[node] = tmp;
> -			else
> -				parsed_hstate->max_huge_pages_node[node] = tmp;
> -			*mhp += tmp;
> -			/* Go to parse next node*/
> -			if (p[count] == ',')
> -				p += count + 1;
> -			else
> -				break;
> -		} else {
> -			if (p != s)
> -				goto invalid;
> -			*mhp = tmp;
> -			break;
> -		}
> -	}
> -
> -	/*
> -	 * Global state is always initialized later in hugetlb_init.
> -	 * But we need to allocate gigantic hstates here early to still
> -	 * use the bootmem allocator.
> -	 */
> -	if (hugetlb_max_hstate && hstate_is_gigantic(parsed_hstate))
> -		hugetlb_hstate_alloc_pages(parsed_hstate);
> -
> -	last_mhp = mhp;
> -
> -	return 1;
> -
> -invalid:
> -	pr_warn("HugeTLB: Invalid hugepages parameter %s\n", p);
> -	hugepages_clear_pages_in_node();
> -	return 1;
> -}
> -__setup("hugepages=", hugepages_setup);
> -
> -/*
> - * hugepagesz command line processing
> - * A specific huge page size can only be specified once with hugepagesz.
> - * hugepagesz is followed by hugepages on the command line.  The global
> - * variable 'parsed_valid_hugepagesz' is used to determine if prior
> - * hugepagesz argument was valid.
> - */
> -static int __init hugepagesz_setup(char *s)
> -{
> -	unsigned long size;
> -	struct hstate *h;
> -
> -	parsed_valid_hugepagesz = false;
> -	size = (unsigned long)memparse(s, NULL);
> -
> -	if (!arch_hugetlb_valid_size(size)) {
> -		pr_err("HugeTLB: unsupported hugepagesz=%s\n", s);
> -		return 1;
> -	}
> -
> -	h = size_to_hstate(size);
> -	if (h) {
> -		/*
> -		 * hstate for this size already exists.  This is normally
> -		 * an error, but is allowed if the existing hstate is the
> -		 * default hstate.  More specifically, it is only allowed if
> -		 * the number of huge pages for the default hstate was not
> -		 * previously specified.
> -		 */
> -		if (!parsed_default_hugepagesz ||  h != &default_hstate ||
> -		    default_hstate.max_huge_pages) {
> -			pr_warn("HugeTLB: hugepagesz=%s specified twice, ignoring\n", s);
> -			return 1;
> -		}
> -
> -		/*
> -		 * No need to call hugetlb_add_hstate() as hstate already
> -		 * exists.  But, do set parsed_hstate so that a following
> -		 * hugepages= parameter will be applied to this hstate.
> -		 */
> -		parsed_hstate = h;
> -		parsed_valid_hugepagesz = true;
> -		return 1;
> -	}
> -
> -	hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT);
> -	parsed_valid_hugepagesz = true;
> -	return 1;
> -}
> -__setup("hugepagesz=", hugepagesz_setup);
> -
> -/*
> - * default_hugepagesz command line input
> - * Only one instance of default_hugepagesz allowed on command line.
> - */
> -static int __init default_hugepagesz_setup(char *s)
> -{
> -	unsigned long size;
> -	int i;
> -
> -	parsed_valid_hugepagesz = false;
> -	if (parsed_default_hugepagesz) {
> -		pr_err("HugeTLB: default_hugepagesz previously specified, ignoring %s\n", s);
> -		return 1;
> -	}
> -
> -	size = (unsigned long)memparse(s, NULL);
> -
> -	if (!arch_hugetlb_valid_size(size)) {
> -		pr_err("HugeTLB: unsupported default_hugepagesz=%s\n", s);
> -		return 1;
> -	}
> -
> -	hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT);
> -	parsed_valid_hugepagesz = true;
> -	parsed_default_hugepagesz = true;
> -	default_hstate_idx = hstate_index(size_to_hstate(size));
> -
> -	/*
> -	 * The number of default huge pages (for this size) could have been
> -	 * specified as the first hugetlb parameter: hugepages=X.  If so,
> -	 * then default_hstate_max_huge_pages is set.  If the default huge
> -	 * page size is gigantic (>= MAX_ORDER), then the pages must be
> -	 * allocated here from bootmem allocator.
> -	 */
> -	if (default_hstate_max_huge_pages) {
> -		default_hstate.max_huge_pages = default_hstate_max_huge_pages;
> -		for_each_online_node(i)
> -			default_hstate.max_huge_pages_node[i] =
> -				default_hugepages_in_node[i];
> -		if (hstate_is_gigantic(&default_hstate))
> -			hugetlb_hstate_alloc_pages(&default_hstate);
> -		default_hstate_max_huge_pages = 0;
> -	}
> -
> -	return 1;
> -}
> -__setup("default_hugepagesz=", default_hugepagesz_setup);
> -
>   static unsigned int allowed_mems_nr(struct hstate *h)
>   {
>   	int node;