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Commit aa888a74 authored by Andi Kleen's avatar Andi Kleen Committed by Linus Torvalds
Browse files

hugetlb: support larger than MAX_ORDER 



This is needed on x86-64 to handle GB pages in hugetlbfs, because it is
not practical to enlarge MAX_ORDER to 1GB.

Instead the 1GB pages are only allocated at boot using the bootmem
allocator using the hugepages=...  option.

These 1G bootmem pages are never freed.  In theory it would be possible to
implement that with some complications, but since it would be a one-way
street (>= MAX_ORDER pages cannot be allocated later) I decided not to
currently.

The >= MAX_ORDER code is not ifdef'ed per architecture.  It is not very
big and the ifdef uglyness seemed not be worth it.

Known problems: /proc/meminfo and "free" do not display the memory
allocated for gb pages in "Total".  This is a little confusing for the
user.

Acked-by: default avatarAndrew Hastings <abh@cray.com>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarNick Piggin <npiggin@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 01ad1c08

mm/hugetlb.c

+81 −2
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/mempolicy.h>

#include <linux/cpuset.h>

#include <linux/mutex.h>

#include <linux/bootmem.h>

#include <linux/sysfs.h>



#include <asm/page.h>
@@ -489,7 +490,7 @@ static void free_huge_page(struct page *page) 
	INIT_LIST_HEAD(&page->lru);



	spin_lock(&hugetlb_lock);

	if (h->surplus_huge_pages_node[nid]) {

	if (h->surplus_huge_pages_node[nid] && huge_page_order(h) < MAX_ORDER) {

		update_and_free_page(h, page);

		h->surplus_huge_pages--;

		h->surplus_huge_pages_node[nid]--;
@@ -550,6 +551,9 @@ static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid) 
{

	struct page *page;



	if (h->order >= MAX_ORDER)

		return NULL;



	page = alloc_pages_node(nid,

		htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|

						__GFP_REPEAT|__GFP_NOWARN,
@@ -616,6 +620,9 @@ static struct page *alloc_buddy_huge_page(struct hstate *h, 
	struct page *page;

	unsigned int nid;



	if (h->order >= MAX_ORDER)

		return NULL;



	/*

	 * Assume we will successfully allocate the surplus page to

	 * prevent racing processes from causing the surplus to exceed
@@ -792,6 +799,10 @@ static void return_unused_surplus_pages(struct hstate *h, 
	/* Uncommit the reservation */

	h->resv_huge_pages -= unused_resv_pages;



	/* Cannot return gigantic pages currently */

	if (h->order >= MAX_ORDER)

		return;



	nr_pages = min(unused_resv_pages, h->surplus_huge_pages);



	while (remaining_iterations-- && nr_pages) {
@@ -913,6 +924,63 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma, 
	return page;

}



static __initdata LIST_HEAD(huge_boot_pages);



struct huge_bootmem_page {

	struct list_head list;

	struct hstate *hstate;

};



static int __init alloc_bootmem_huge_page(struct hstate *h)

{

	struct huge_bootmem_page *m;

	int nr_nodes = nodes_weight(node_online_map);



	while (nr_nodes) {

		void *addr;



		addr = __alloc_bootmem_node_nopanic(

				NODE_DATA(h->hugetlb_next_nid),

				huge_page_size(h), huge_page_size(h), 0);



		if (addr) {

			/*

			 * Use the beginning of the huge page to store the

			 * huge_bootmem_page struct (until gather_bootmem

			 * puts them into the mem_map).

			 */

			m = addr;

			if (m)

				goto found;

		}

		hstate_next_node(h);

		nr_nodes--;

	}

	return 0;



found:

	BUG_ON((unsigned long)virt_to_phys(m) & (huge_page_size(h) - 1));

	/* Put them into a private list first because mem_map is not up yet */

	list_add(&m->list, &huge_boot_pages);

	m->hstate = h;

	return 1;

}



/* Put bootmem huge pages into the standard lists after mem_map is up */

static void __init gather_bootmem_prealloc(void)

{

	struct huge_bootmem_page *m;



	list_for_each_entry(m, &huge_boot_pages, list) {

		struct page *page = virt_to_page(m);

		struct hstate *h = m->hstate;

		__ClearPageReserved(page);

		WARN_ON(page_count(page) != 1);

		prep_compound_page(page, h->order);

		prep_new_huge_page(h, page, page_to_nid(page));

	}

}



static void __init hugetlb_init_one_hstate(struct hstate *h)

{

	unsigned long i;
@@ -923,7 +991,10 @@ static void __init hugetlb_init_one_hstate(struct hstate *h) 
	h->hugetlb_next_nid = first_node(node_online_map);



	for (i = 0; i < h->max_huge_pages; ++i) {

		if (!alloc_fresh_huge_page(h))

		if (h->order >= MAX_ORDER) {

			if (!alloc_bootmem_huge_page(h))

				break;

		} else if (!alloc_fresh_huge_page(h))

			break;

	}

	h->max_huge_pages = h->free_huge_pages = h->nr_huge_pages = i;
@@ -956,6 +1027,9 @@ static void try_to_free_low(struct hstate *h, unsigned long count) 
{

	int i;



	if (h->order >= MAX_ORDER)

		return;



	for (i = 0; i < MAX_NUMNODES; ++i) {

		struct page *page, *next;

		struct list_head *freel = &h->hugepage_freelists[i];
@@ -982,6 +1056,9 @@ static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count) 
{

	unsigned long min_count, ret;



	if (h->order >= MAX_ORDER)

		return h->max_huge_pages;



	/*

	 * Increase the pool size

	 * First take pages out of surplus state.  Then make up the
@@ -1210,6 +1287,8 @@ static int __init hugetlb_init(void) 


	hugetlb_init_hstates();



	gather_bootmem_prealloc();



	report_hugepages();



	hugetlb_sysfs_init();