From mboxrd@z Thu Jan 1 00:00:00 1970 From: Janosch Frank Subject: [RFC/PATCH v3 14/16] s390/mm: hugetlb pages within a gmap can not be freed Date: Fri, 9 Feb 2018 10:34:22 +0100 Message-ID: <1518168864-147803-15-git-send-email-frankja@linux.vnet.ibm.com> References: <1518168864-147803-1-git-send-email-frankja@linux.vnet.ibm.com> Cc: schwidefsky@de.ibm.com, borntraeger@de.ibm.com, david@redhat.com, dominik.dingel@gmail.com, linux-s390@vger.kernel.org To: kvm@vger.kernel.org Return-path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:37058 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752611AbeBIJhs (ORCPT ); Fri, 9 Feb 2018 04:37:48 -0500 Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w199ZSLD107262 for ; Fri, 9 Feb 2018 04:37:48 -0500 Received: from e06smtp12.uk.ibm.com (e06smtp12.uk.ibm.com [195.75.94.108]) by mx0a-001b2d01.pphosted.com with ESMTP id 2g17f9vvt8-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 09 Feb 2018 04:37:47 -0500 Received: from localhost by e06smtp12.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 9 Feb 2018 09:37:45 -0000 In-Reply-To: <1518168864-147803-1-git-send-email-frankja@linux.vnet.ibm.com> Sender: kvm-owner@vger.kernel.org List-ID: From: Dominik Dingel Guests backed by huge pages could theoretically free unused pages via the diagnose 10 instruction. We currently don't allow that, so we don't have to refault it once it's needed again. Signed-off-by: Dominik Dingel Reviewed-by: Martin Schwidefsky --- arch/s390/mm/gmap.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c index 482bbf1..0b81863 100644 --- a/arch/s390/mm/gmap.c +++ b/arch/s390/mm/gmap.c @@ -722,6 +722,9 @@ void gmap_discard(struct gmap *gmap, unsigned long from, unsigned long to) vmaddr |= gaddr & ~PMD_MASK; /* Find vma in the parent mm */ vma = find_vma(gmap->mm, vmaddr); + /* We do not discard pages that are backed by hugetlbfs */ + if (vma && is_vm_hugetlb_page(vma)) + continue; size = min(to - gaddr, PMD_SIZE - (gaddr & ~PMD_MASK)); zap_page_range(vma, vmaddr, size); } -- 2.7.4