From owner-svn-src-all@freebsd.org Mon Apr 10 21:01:44 2017 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 1434DD3797F; Mon, 10 Apr 2017 21:01:44 +0000 (UTC) (envelope-from markj@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id D806AC7B; Mon, 10 Apr 2017 21:01:43 +0000 (UTC) (envelope-from markj@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id v3AL1gsJ042364; Mon, 10 Apr 2017 21:01:42 GMT (envelope-from markj@FreeBSD.org) Received: (from markj@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id v3AL1gdt042363; Mon, 10 Apr 2017 21:01:42 GMT (envelope-from markj@FreeBSD.org) Message-Id: <201704102101.v3AL1gdt042363@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: markj set sender to markj@FreeBSD.org using -f From: Mark Johnston Date: Mon, 10 Apr 2017 21:01:42 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r316689 - head/sys/vm X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 10 Apr 2017 21:01:44 -0000 Author: markj Date: Mon Apr 10 21:01:42 2017 New Revision: 316689 URL: https://svnweb.freebsd.org/changeset/base/316689 Log: Busy the map in vm_map_protect(). We are otherwise susceptible to a race with a concurrent vm_map_wire(), which may drop the map lock to fault pages into the object chain. In particular, vm_map_protect() will only copy newly writable wired pages into the top-level object when MAP_ENTRY_USER_WIRED is set, but vm_map_wire() only sets this flag after its fault loop. We may thus end up with a writable wired entry whose top-level object does not contain the entire range of pages. Reported and tested by: pho Reviewed by: kib MFC after: 1 week Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D10349 Modified: head/sys/vm/vm_map.c Modified: head/sys/vm/vm_map.c ============================================================================== --- head/sys/vm/vm_map.c Mon Apr 10 21:00:47 2017 (r316688) +++ head/sys/vm/vm_map.c Mon Apr 10 21:01:42 2017 (r316689) @@ -1965,6 +1965,14 @@ vm_map_protect(vm_map_t map, vm_offset_t vm_map_lock(map); + /* + * Ensure that we are not concurrently wiring pages. vm_map_wire() may + * need to fault pages into the map and will drop the map lock while + * doing so, and the VM object may end up in an inconsistent state if we + * update the protection on the map entry in between faults. + */ + vm_map_wait_busy(map); + VM_MAP_RANGE_CHECK(map, start, end); if (vm_map_lookup_entry(map, start, &entry)) {