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Date: Mon, 17 Mar 2008 02:58:26 +0100 (CET)
From: Andi Kleen <andi@...stfloor.org>
To: linux-kernel@...r.kernel.org, pj@....com, linux-mm@...ck.org,
nickpiggin@...oo.com.au
Subject: [PATCH] [12/18] Add support to allocate hugetlb pages that are 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.
Signed-off-by: Andi Kleen <ak@...e.de>
---
mm/hugetlb.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 62 insertions(+), 2 deletions(-)
Index: linux/mm/hugetlb.c
===================================================================
--- linux.orig/mm/hugetlb.c
+++ linux/mm/hugetlb.c
@@ -14,6 +14,7 @@
#include <linux/mempolicy.h>
#include <linux/cpuset.h>
#include <linux/mutex.h>
+#include <linux/bootmem.h>
#include <asm/page.h>
#include <asm/pgtable.h>
@@ -153,7 +154,7 @@ static void free_huge_page(struct page *
INIT_LIST_HEAD(&page->lru);
spin_lock(&hugetlb_lock);
- if (h->surplus_huge_pages_node[nid]) {
+ if (h->surplus_huge_pages_node[nid] && h->order <= MAX_ORDER) {
update_and_free_page(h, page);
h->surplus_huge_pages--;
h->surplus_huge_pages_node[nid]--;
@@ -215,6 +216,9 @@ static struct page *alloc_fresh_huge_pag
{
struct page *page;
+ if (h->order > MAX_ORDER)
+ return NULL;
+
page = alloc_pages_node(nid,
htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|__GFP_NOWARN,
huge_page_order(h));
@@ -271,6 +275,9 @@ static struct page *alloc_buddy_huge_pag
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
@@ -422,6 +429,10 @@ return_unused_surplus_pages(struct hstat
/* 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 (nr_pages) {
@@ -499,6 +510,44 @@ static struct page *alloc_huge_page(stru
return page;
}
+static __initdata LIST_HEAD(huge_boot_pages);
+
+struct huge_bm_page {
+ struct list_head list;
+ struct hstate *hstate;
+};
+
+static int __init alloc_bm_huge_page(struct hstate *h)
+{
+ struct huge_bm_page *m;
+ m = __alloc_bootmem_node_nopanic(NODE_DATA(h->hugetlb_next_nid),
+ huge_page_size(h), huge_page_size(h),
+ 0);
+ if (!m)
+ return 0;
+ 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;
+ huge_next_node(h);
+ return 1;
+}
+
+/* Put bootmem huge pages into the standard lists after mem_map is up */
+static int __init huge_init_bm(void)
+{
+ struct huge_bm_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);
+ prep_compound_page(page, h->order);
+ huge_new_page(h, page);
+ }
+ return 0;
+}
+__initcall(huge_init_bm);
+
static int __init hugetlb_init_hstate(struct hstate *h)
{
unsigned long i;
@@ -509,7 +558,10 @@ static int __init hugetlb_init_hstate(st
h->hugetlb_next_nid = first_node(node_online_map);
for (i = 0; i < max_huge_pages[h - hstates]; ++i) {
- if (!alloc_fresh_huge_page(h))
+ if (h->order > MAX_ORDER) {
+ if (!alloc_bm_huge_page(h))
+ break;
+ } else if (!alloc_fresh_huge_page(h))
break;
}
max_huge_pages[h - hstates] = h->free_huge_pages = h->nr_huge_pages = i;
@@ -581,6 +633,9 @@ static void do_try_to_free_low(struct hs
{
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];
@@ -618,6 +673,11 @@ set_max_huge_pages(struct hstate *h, uns
*err = 0;
+ if (h->order > MAX_ORDER) {
+ *err = -EINVAL;
+ return max_huge_pages[h - hstates];
+ }
+
/*
* Increase the pool size
* First take pages out of surplus state. Then make up the
--
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