Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756482AbbEUPth (ORCPT ); Thu, 21 May 2015 11:49:37 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:21963 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754356AbbEUPtU (ORCPT ); Thu, 21 May 2015 11:49:20 -0400 From: Mike Kravetz To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Dave Hansen , Naoya Horiguchi , David Rientjes , Hugh Dickins , Davidlohr Bueso , Aneesh Kumar , Hillf Danton , Christoph Hellwig , Mike Kravetz Subject: [RFC v3 PATCH 08/10] mm/hugetlb: vma_has_reserves() needs to handle fallocate hole punch Date: Thu, 21 May 2015 08:47:42 -0700 Message-Id: <1432223264-4414-9-git-send-email-mike.kravetz@oracle.com> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1432223264-4414-1-git-send-email-mike.kravetz@oracle.com> References: <1432223264-4414-1-git-send-email-mike.kravetz@oracle.com> X-Source-IP: aserv0021.oracle.com [141.146.126.233] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1651 Lines: 48 In vma_has_reserves(), the current assumption is that reserves are always present for shared mappings. However, will not be the case with fallocate hole punch. When punching a hole, the present page will be deleted as well as the region/reserve map entry (and hence any reservation). vma_has_reserves is passed "chg" which indicates whether or not a region/reserve map is present. Use this to determine if reserves are actually present or were removed via hole punch. Signed-off-by: Mike Kravetz --- mm/hugetlb.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 449cf5f..94c6154 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -559,9 +559,19 @@ static int vma_has_reserves(struct vm_area_struct *vma, long chg) return 0; } - /* Shared mappings always use reserves */ - if (vma->vm_flags & VM_MAYSHARE) - return 1; + if (vma->vm_flags & VM_MAYSHARE) { + /* + * We know VM_NORESERVE is not set. Therefore, there SHOULD + * be a region map for all pages. The only situation where + * there is no region map is if a hole was punched via + * fallocate. In this case, there really are no reverves to + * use. This situation is indicated if chg != 0. + */ + if (chg) + return 0; + else + return 1; + } /* * Only the process that called mmap() has reserves for -- 2.1.0 -- 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/