Messages in this thread Patch in this message | | | From | Andi Kleen <> | Subject | [PATCH] [12/18] Add support to allocate hugetlb pages that are larger than MAX_ORDER | Date | Mon, 17 Mar 2008 02:58:26 +0100 (CET) |
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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@suse.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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