From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932295AbbFWAkb (ORCPT ); Mon, 22 Jun 2015 20:40:31 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:38527 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752833AbbFWAjr (ORCPT ); Mon, 22 Jun 2015 20:39:47 -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 v5 PATCH 5/9] mm/hugetlb: vma_has_reserves() needs to handle fallocate hole punch Date: Mon, 22 Jun 2015 17:38:35 -0700 Message-Id: <1435019919-29225-6-git-send-email-mike.kravetz@oracle.com> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1435019919-29225-1-git-send-email-mike.kravetz@oracle.com> References: <1435019919-29225-1-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 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 7cd4b67..9d2859f 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -692,9 +692,19 @@ 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 Please read the FAQ at http://www.tux.org/lkml/