From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f53.google.com (mail-pa0-f53.google.com [209.85.220.53]) by kanga.kvack.org (Postfix) with ESMTP id 8E5436B025F for ; Fri, 20 Nov 2015 03:07:33 -0500 (EST) Received: by padhx2 with SMTP id hx2so109422450pad.1 for ; Fri, 20 Nov 2015 00:07:33 -0800 (PST) Received: from out11.biz.mail.alibaba.com (out114-135.biz.mail.alibaba.com. [205.204.114.135]) by mx.google.com with ESMTP id 79si390011pfi.210.2015.11.20.00.07.31 for ; Fri, 20 Nov 2015 00:07:32 -0800 (PST) Reply-To: "Hillf Danton" From: "Hillf Danton" 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 Content-Language: zh-cn Sender: owner-linux-mm@kvack.org List-ID: To: 'Naoya Horiguchi' , 'Andrew Morton' Cc: 'David Rientjes' , 'Dave Hansen' , 'Mel Gorman' , 'Joonsoo Kim' , 'Mike Kravetz' , linux-mm@kvack.org, linux-kernel@vger.kernel.org, 'Naoya Horiguchi' > > 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org