Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751116AbbKXFEx (ORCPT ); Tue, 24 Nov 2015 00:04:53 -0500 Received: from TYO201.gate.nec.co.jp ([210.143.35.51]:59303 "EHLO tyo201.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750699AbbKXFEv convert rfc822-to-8bit (ORCPT ); Tue, 24 Nov 2015 00:04:51 -0500 From: Naoya Horiguchi To: Andrew Morton CC: Hillf Danton , "'David Rientjes'" , "'Dave Hansen'" , "'Mel Gorman'" , "'Joonsoo Kim'" , "'Mike Kravetz'" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "'Naoya Horiguchi'" Subject: Re: [PATCH v1] mm: hugetlb: fix hugepage memory leak caused by wrong reserve count Thread-Topic: [PATCH v1] mm: hugetlb: fix hugepage memory leak caused by wrong reserve count Thread-Index: AQHRI2PslGkcal4fn0KZMoXK0xVcf56j9IOAgADy4ACABSXZAA== Date: Tue, 24 Nov 2015 05:03:34 +0000 Message-ID: <20151124050323.GA31053@hori1.linux.bs1.fc.nec.co.jp> References: <1448004017-23679-1-git-send-email-n-horiguchi@ah.jp.nec.com> <050201d12369$167a0a10$436e1e30$@alibaba-inc.com> <20151120142638.c505927a43dc1ede32570db0@linux-foundation.org> In-Reply-To: <20151120142638.c505927a43dc1ede32570db0@linux-foundation.org> Accept-Language: ja-JP, en-US Content-Language: ja-JP X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.128.101.24] Content-Type: text/plain; charset="iso-2022-jp" Content-ID: <64C2FB06565D2B4183A1583A513BAEF6@gisp.nec.co.jp> Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3509 Lines: 87 On Fri, Nov 20, 2015 at 02:26:38PM -0800, Andrew Morton wrote: > On Fri, 20 Nov 2015 15:57:21 +0800 "Hillf Danton" wrote: > > > > > > > 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 > > > Cc: [3.16+] > > > --- > > > - the reason why I set stable target to "3.16+" is that this patch can be > > > applied easily/automatically on these versions. But this bug seems to be > > > old one, so if you are interested in backporting to older kernels, > > > please let me know. > > > --- > > > mm/hugetlb.c | 5 ++++- > > > 1 files changed, 4 insertions(+), 1 deletions(-) > > > > > > diff --git v4.3/mm/hugetlb.c v4.3_patched/mm/hugetlb.c > > > index 9cc7734..77c518c 100644 > > > --- v4.3/mm/hugetlb.c > > > +++ v4.3_patched/mm/hugetlb.c > > > @@ -1790,7 +1790,10 @@ struct page *alloc_huge_page(struct vm_area_struct *vma, > > > page = alloc_buddy_huge_page(h, NUMA_NO_NODE); > > > if (!page) > > > goto out_uncharge_cgroup; > > > - > > > + if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) { > > > + SetPagePrivate(page); > > > + h->resv_huge_pages--; > > > + } > > > > I am wondering if this patch was prepared against the next tree. > > It's against 4.3. Hi Hillf, Andrew, That's right, this was against 4.3, and I agree with the adjustment for next as done below. > Here's the version I have, against current -linus: > > --- 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 */ > > It needs a careful re-review and, preferably, retest please. I retested and made sure that the fix works on next-20151123. Thanks, Naoya Horiguchi > Probably when Greg comes to merge this he'll hit problems and we'll > need to provide him with the against-4.3 patch. > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/