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authorHillf Danton <dhillf@gmail.com>2012-03-21 16:34:00 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-21 17:54:57 -0700
commit28073b02bfaaed1e3278acfb8e6e7c9f76d9f2b6 (patch)
tree54ab2952e2bee85780438a011cf5c1f198ff3dd9 /mm
parentcc715d99e529d470dde2f33a6614f255adea71f3 (diff)
downloadlwn-28073b02bfaaed1e3278acfb8e6e7c9f76d9f2b6.tar.gz
lwn-28073b02bfaaed1e3278acfb8e6e7c9f76d9f2b6.zip
mm: hugetlb: defer freeing pages when gathering surplus pages
When gathering surplus pages, the number of needed pages is recomputed after reacquiring hugetlb lock to catch changes in resv_huge_pages and free_huge_pages. Plus it is recomputed with the number of newly allocated pages involved. Thus freeing pages can be deferred a bit to see if the final page request is satisfied, though pages could be allocated less than needed. Signed-off-by: Hillf Danton <dhillf@gmail.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/hugetlb.c30
1 files changed, 17 insertions, 13 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index a876871f6be5..afe3e1ff919b 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -852,6 +852,7 @@ static int gather_surplus_pages(struct hstate *h, int delta)
struct page *page, *tmp;
int ret, i;
int needed, allocated;
+ bool alloc_ok = true;
needed = (h->resv_huge_pages + delta) - h->free_huge_pages;
if (needed <= 0) {
@@ -867,17 +868,13 @@ retry:
spin_unlock(&hugetlb_lock);
for (i = 0; i < needed; i++) {
page = alloc_buddy_huge_page(h, NUMA_NO_NODE);
- if (!page)
- /*
- * We were not able to allocate enough pages to
- * satisfy the entire reservation so we free what
- * we've allocated so far.
- */
- goto free;
-
+ if (!page) {
+ alloc_ok = false;
+ break;
+ }
list_add(&page->lru, &surplus_list);
}
- allocated += needed;
+ allocated += i;
/*
* After retaking hugetlb_lock, we need to recalculate 'needed'
@@ -886,9 +883,16 @@ retry:
spin_lock(&hugetlb_lock);
needed = (h->resv_huge_pages + delta) -
(h->free_huge_pages + allocated);
- if (needed > 0)
- goto retry;
-
+ if (needed > 0) {
+ if (alloc_ok)
+ goto retry;
+ /*
+ * We were not able to allocate enough pages to
+ * satisfy the entire reservation so we free what
+ * we've allocated so far.
+ */
+ goto free;
+ }
/*
* The surplus_list now contains _at_least_ the number of extra pages
* needed to accommodate the reservation. Add the appropriate number
@@ -914,10 +918,10 @@ retry:
VM_BUG_ON(page_count(page));
enqueue_huge_page(h, page);
}
+free:
spin_unlock(&hugetlb_lock);
/* Free unnecessary surplus pages to the buddy allocator */
-free:
if (!list_empty(&surplus_list)) {
list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
list_del(&page->lru);