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[PATCH] hugepage allocator cleanup 

Insert "fresh" huge pages into the hugepage allocator by the same means as
they are freed back into it.  This reduces code size and allows
enqueue_huge_page to be inlined into the hugepage free fastpath.

Eliminate occurances of hugepages on the free list with non-zero refcount.
This can allow stricter refcount checks in future.  Also required for
lockless pagecache.

Signed-off-by: Nick Piggin <npiggin@suse.de>

"This patch also eliminates a leak "cleaned up" by re-clobbering the
refcount on every allocation from the hugepage freelists.  With respect to
the lockless pagecache, the crucial aspect is to eliminate unconditional
set_page_count() to 0 on pages with potentially nonzero refcounts, though
closer inspection suggests the assignments removed are entirely spurious."

Acked-by: William Irwin <wli@holomorphy.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Nick Piggin 2006-03-22 00:08:08 -08:00 committed by Linus Torvalds
parent 545b1ea9bf
commit a482289d46
1 changed files with 8 additions and 16 deletions
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24
mm/hugetlb.c
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@ -64,7 +64,7 @@ static struct page *dequeue_huge_page(struct vm_area_struct *vma,
return page;
}
static struct page *alloc_fresh_huge_page(void)
static int alloc_fresh_huge_page(void)
{
static int nid = 0;
struct page *page;
@ -72,12 +72,15 @@ static struct page *alloc_fresh_huge_page(void)
HUGETLB_PAGE_ORDER);
nid = (nid + 1) % num_online_nodes();
if (page) {
page[1].lru.next = (void *)free_huge_page; /* dtor */
spin_lock(&hugetlb_lock);
nr_huge_pages++;
nr_huge_pages_node[page_to_nid(page)]++;
spin_unlock(&hugetlb_lock);
put_page(page); /* free it into the hugepage allocator */
return 1;
}
return page;
return 0;
}
void free_huge_page(struct page *page)
@ -85,7 +88,6 @@ void free_huge_page(struct page *page)
BUG_ON(page_count(page));
INIT_LIST_HEAD(&page->lru);
page[1].lru.next = NULL; /* reset dtor */
spin_lock(&hugetlb_lock);
enqueue_huge_page(page);
@ -105,7 +107,6 @@ struct page *alloc_huge_page(struct vm_area_struct *vma, unsigned long addr)
}
spin_unlock(&hugetlb_lock);
set_page_count(page, 1);
page[1].lru.next = (void *)free_huge_page; /* set dtor */
for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); ++i)
clear_user_highpage(&page[i], addr);
return page;
@ -114,7 +115,6 @@ struct page *alloc_huge_page(struct vm_area_struct *vma, unsigned long addr)
static int __init hugetlb_init(void)
{
unsigned long i;
struct page *page;
if (HPAGE_SHIFT == 0)
return 0;
@ -123,12 +123,8 @@ static int __init hugetlb_init(void)
INIT_LIST_HEAD(&hugepage_freelists[i]);
for (i = 0; i < max_huge_pages; ++i) {
page = alloc_fresh_huge_page();
if (!page)
if (!alloc_fresh_huge_page())
break;
spin_lock(&hugetlb_lock);
enqueue_huge_page(page);
spin_unlock(&hugetlb_lock);
}
max_huge_pages = free_huge_pages = nr_huge_pages = i;
printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages);
@ -154,8 +150,8 @@ static void update_and_free_page(struct page *page)
page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
1 << PG_private | 1<< PG_writeback);
set_page_count(&page[i], 0);
}
page[1].lru.next = NULL;
set_page_count(page, 1);
__free_pages(page, HUGETLB_PAGE_ORDER);
}
@ -188,12 +184,8 @@ static inline void try_to_free_low(unsigned long count)
static unsigned long set_max_huge_pages(unsigned long count)
{
while (count > nr_huge_pages) {
struct page *page = alloc_fresh_huge_page();
if (!page)
if (!alloc_fresh_huge_page())
return nr_huge_pages;
spin_lock(&hugetlb_lock);
enqueue_huge_page(page);
spin_unlock(&hugetlb_lock);
}
if (count >= nr_huge_pages)
return nr_huge_pages;