From patchwork Thu Mar 5 17:18:00 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrea Arcangeli X-Patchwork-Id: 5948381 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 77C30BF440 for ; Thu, 5 Mar 2015 17:25:41 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id A3CF1202E5 for ; Thu, 5 Mar 2015 17:25:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C9BF9202B8 for ; Thu, 5 Mar 2015 17:25:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422639AbbCERZM (ORCPT ); Thu, 5 Mar 2015 12:25:12 -0500 Received: from mx1.redhat.com ([209.132.183.28]:60797 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752973AbbCERTS (ORCPT ); Thu, 5 Mar 2015 12:19:18 -0500 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id t25HIDam031703 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 5 Mar 2015 12:18:13 -0500 Received: from mail.random (ovpn-116-22.ams2.redhat.com [10.36.116.22]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t25HIBvW005672 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Thu, 5 Mar 2015 12:18:12 -0500 From: Andrea Arcangeli To: qemu-devel@nongnu.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org, Android Kernel Team Cc: "Kirill A. Shutemov" , Pavel Emelyanov , Sanidhya Kashyap , zhang.zhanghailiang@huawei.com, Linus Torvalds , Andres Lagar-Cavilla , Dave Hansen , Paolo Bonzini , Rik van Riel , Mel Gorman , Andy Lutomirski , Andrew Morton , Sasha Levin , Hugh Dickins , Peter Feiner , "Dr. David Alan Gilbert" , Christopher Covington , Johannes Weiner , Robert Love , Dmitry Adamushko , Neil Brown , Mike Hommey , Taras Glek , Jan Kara , KOSAKI Motohiro , Michel Lespinasse , Minchan Kim , Keith Packard , "Huangpeng (Peter)" , Anthony Liguori , Stefan Hajnoczi , Wenchao Xia , Andrew Jones , Juan Quintela Subject: [PATCH 17/21] userfaultfd: remap_pages: swp_entry_swapcount() preparation Date: Thu, 5 Mar 2015 18:18:00 +0100 Message-Id: <1425575884-2574-18-git-send-email-aarcange@redhat.com> In-Reply-To: <1425575884-2574-1-git-send-email-aarcange@redhat.com> References: <1425575884-2574-1-git-send-email-aarcange@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.27 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Provide a new swapfile method for remap_pages() to verify the swap entry is mapped only in one vma before relocating the swap entry in a different virtual address. Otherwise if the swap entry is mapped in multiple vmas, when the page is swapped back in, it could get mapped in a non linear way in some anon_vma. Signed-off-by: Andrea Arcangeli --- include/linux/swap.h | 6 ++++++ mm/swapfile.c | 13 +++++++++++++ 2 files changed, 19 insertions(+) -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/include/linux/swap.h b/include/linux/swap.h index 4759491..9adda11 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -436,6 +436,7 @@ extern unsigned int count_swap_pages(int, int); extern sector_t map_swap_page(struct page *, struct block_device **); extern sector_t swapdev_block(int, pgoff_t); extern int page_swapcount(struct page *); +extern int swp_entry_swapcount(swp_entry_t entry); extern struct swap_info_struct *page_swap_info(struct page *); extern int reuse_swap_page(struct page *); extern int try_to_free_swap(struct page *); @@ -527,6 +528,11 @@ static inline int page_swapcount(struct page *page) return 0; } +static inline int swp_entry_swapcount(swp_entry_t entry) +{ + return 0; +} + #define reuse_swap_page(page) (page_mapcount(page) == 1) static inline int try_to_free_swap(struct page *page) diff --git a/mm/swapfile.c b/mm/swapfile.c index 63f55cc..04c7621 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -874,6 +874,19 @@ int page_swapcount(struct page *page) return count; } +int swp_entry_swapcount(swp_entry_t entry) +{ + int count = 0; + struct swap_info_struct *p; + + p = swap_info_get(entry); + if (p) { + count = swap_count(p->swap_map[swp_offset(entry)]); + spin_unlock(&p->lock); + } + return count; +} + /* * We can write to an anon page without COW if there are no other references * to it. And as a side-effect, free up its swap: because the old content