From: Naoya Horiguchi <[email protected]> Subject: mm: hugetlb: fix hugepage memory leak caused by wrong reserve count
When dequeue_huge_page_vma() in alloc_huge_page() fails, we fall back to 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 <[email protected]> Cc: David Rientjes <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Mel Gorman <[email protected]> Cc: Joonsoo Kim <[email protected]> Cc: Hillf Danton <[email protected]> Cc: Mike Kravetz <[email protected]> Cc: <[email protected]> [3.16+] Signed-off-by: Andrew Morton <[email protected]> --- mm/hugetlb.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff -puN mm/hugetlb.c~mm-hugetlb-fix-hugepage-memory-leak-caused-by-wrong-reserve-count mm/hugetlb.c --- a/mm/hugetlb.c~mm-hugetlb-fix-hugepage-memory-leak-caused-by-wrong-reserve-count +++ a/mm/hugetlb.c @@ -1886,7 +1886,10 @@ struct page *alloc_huge_page(struct vm_a 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 */ _ -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
