Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752055AbbGMEX0 (ORCPT ); Mon, 13 Jul 2015 00:23:26 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:30002 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751693AbbGMEWG (ORCPT ); Mon, 13 Jul 2015 00:22:06 -0400 From: Mike Kravetz To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org Cc: Dave Hansen , Naoya Horiguchi , David Rientjes , Hugh Dickins , Davidlohr Bueso , Aneesh Kumar , Hillf Danton , Christoph Hellwig , Andrew Morton , Michal Hocko , Mike Kravetz Subject: [PATCH v3 06/10] mm/hugetlb: vma_has_reserves() needs to handle fallocate hole punch Date: Sun, 12 Jul 2015 21:21:04 -0700 Message-Id: <1436761268-6397-7-git-send-email-mike.kravetz@oracle.com> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1436761268-6397-1-git-send-email-mike.kravetz@oracle.com> References: <1436761268-6397-1-git-send-email-mike.kravetz@oracle.com> X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1656 Lines: 49 In vma_has_reserves(), the current assumption is that reserves are always present for shared mappings. However, this 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 def39e3..f72cb96 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -801,9 +801,19 @@ 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/