Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1162088AbbKTIDU (ORCPT ); Fri, 20 Nov 2015 03:03:20 -0500 Received: from out4133-2.mail.aliyun.com ([42.120.133.2]:47372 "EHLO out4133-2.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935001AbbKTIDP (ORCPT ); Fri, 20 Nov 2015 03:03:15 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R151e4;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e02c03310;MF=hillf.zj@alibaba-inc.com;NM=1;PH=DS;RN=10;SR=0;TI=SMTPD_----4DlIHBX; Reply-To: "Hillf Danton" From: "Hillf Danton" To: "'Naoya Horiguchi'" , "'Andrew Morton'" Cc: "'David Rientjes'" , "'Dave Hansen'" , "'Mel Gorman'" , "'Joonsoo Kim'" , "'Mike Kravetz'" , , , "'Naoya Horiguchi'" References: <1448004017-23679-1-git-send-email-n-horiguchi@ah.jp.nec.com> In-Reply-To: <1448004017-23679-1-git-send-email-n-horiguchi@ah.jp.nec.com> Subject: Re: [PATCH v1] mm: hugetlb: fix hugepage memory leak caused by wrong reserve count Date: Fri, 20 Nov 2015 15:57:21 +0800 Message-ID: <050201d12369$167a0a10$436e1e30$@alibaba-inc.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Outlook 14.0 Thread-Index: AQJHUNcjnEQLZ4mgKYMy6P7F6lmKu524L5+g Content-Language: zh-cn Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2312 Lines: 57 > > 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. > spin_lock(&hugetlb_lock); > list_move(&page->lru, &h->hugepage_activelist); > /* Fall through */ > -- > 1.7.1 -- 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/