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authorNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>2015-12-11 13:40:24 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-12-12 10:15:34 -0800
commita88c769548047b21f76fd71e04b6a3300ff17160 (patch)
tree29db452a002d99d40bda95a42a586fb52ddb98c3
parentb9d85451ddd4e7f2d6280506f6fe7f1924356924 (diff)
downloadlinux-a88c769548047b21f76fd71e04b6a3300ff17160.tar.gz
mm: hugetlb: fix hugepage memory leak caused by wrong reserve count
When dequeue_huge_page_vma() in alloc_huge_page() fails, we fall back on alloc_buddy_huge_page() to directly create a hugepage from the buddy allocator. In that case, however, if alloc_buddy_huge_page() succeeds we don't decrement h->resv_huge_pages, which means that successful hugetlb_fault() returns without releasing the reserve count. As a result, subsequent hugetlb_fault() might fail despite that there are still free hugepages. This patch simply adds decrementing code on that code path. I reproduced this problem when testing v4.3 kernel in the following situation: - the test machine/VM is a NUMA system, - hugepage overcommiting is enabled, - most of hugepages are allocated and there's only one free hugepage which is on node 0 (for example), - another program, which calls set_mempolicy(MPOL_BIND) to bind itself to node 1, tries to allocate a hugepage, - the allocation should fail but the reserve count is still hold. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: David Rientjes <rientjes@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: <stable@vger.kernel.org> [3.16+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/hugetlb.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 827bb02a43a4..4fe4340ed9b7 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1886,7 +1886,10 @@ struct page *alloc_huge_page(struct vm_area_struct *vma,
page = __alloc_buddy_huge_page_with_mpol(h, vma, addr);
if (!page)
goto out_uncharge_cgroup;
-
+ if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) {
+ SetPagePrivate(page);
+ h->resv_huge_pages--;
+ }
spin_lock(&hugetlb_lock);
list_move(&page->lru, &h->hugepage_activelist);
/* Fall through */