From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763773AbXKOGUO (ORCPT ); Thu, 15 Nov 2007 01:20:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759717AbXKOGQd (ORCPT ); Thu, 15 Nov 2007 01:16:33 -0500 Received: from pentafluge.infradead.org ([213.146.154.40]:51055 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762418AbXKOGQa (ORCPT ); Thu, 15 Nov 2007 01:16:30 -0500 Date: Wed, 14 Nov 2007 22:14:54 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , Domenico Andreoli , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, uml-devel , Lepton Wu , Jeff Dike Subject: [patch 10/19] UML - kill subprocesses on exit Message-ID: <20071115061454.GK7980@kroah.com> References: <20071115054813.977066477@mini.kroah.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline; filename="uml-kill-subprocesses-on-exit.patch" In-Reply-To: <20071115061415.GA7980@kroah.com> User-Agent: Mutt/1.5.16 (2007-06-09) X-Bad-Reply: References and In-Reply-To but no 'Re:' in Subject. Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org -stable review patch. If anyone has any objections, please let us know. ------------------ From: Lepton Wu commit a24864a1d52a97e345a6bd4862a057f98364d098 uml: definitively kill subprocesses on panic In a stock 2.6.22.6 kernel, poweroff a user mode linux guest (2.6.22.6 running in skas0 mode) will halt the host linux. I think the reason is the kernel thread abort because of a bug. Then the sys_reboot in process of user mode linux guest is not trapped by the user mode linux kernel and is executed by host. I think it is better to make sure all of our children process to quit when user mode linux kernel abort. [ jdike - the kernel process needs to ignore SIGTERM, plus the waitpid/kill loop is needed to make sure that all of our children are dead before the kernel exits ] Signed-off-by: Lepton Wu Signed-off-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- arch/um/os-Linux/skas/process.c | 2 +- arch/um/os-Linux/util.c | 38 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 39 insertions(+), 1 deletion(-) --- a/arch/um/os-Linux/skas/process.c +++ b/arch/um/os-Linux/skas/process.c @@ -182,7 +182,7 @@ static int userspace_tramp(void *stack) ptrace(PTRACE_TRACEME, 0, 0, 0); - init_new_thread_signals(); + signal(SIGTERM, SIG_DFL); err = set_interval(1); if(err) panic("userspace_tramp - setting timer failed, errno = %d\n", --- a/arch/um/os-Linux/util.c +++ b/arch/um/os-Linux/util.c @@ -105,6 +105,44 @@ int setjmp_wrapper(void (*proc)(void *, void os_dump_core(void) { + int pid; + signal(SIGSEGV, SIG_DFL); + + /* + * We are about to SIGTERM this entire process group to ensure that + * nothing is around to run after the kernel exits. The + * kernel wants to abort, not die through SIGTERM, so we + * ignore it here. + */ + + signal(SIGTERM, SIG_IGN); + kill(0, SIGTERM); + /* + * Most of the other processes associated with this UML are + * likely sTopped, so give them a SIGCONT so they see the + * SIGTERM. + */ + kill(0, SIGCONT); + + /* + * Now, having sent signals to everyone but us, make sure they + * die by ptrace. Processes can survive what's been done to + * them so far - the mechanism I understand is receiving a + * SIGSEGV and segfaulting immediately upon return. There is + * always a SIGSEGV pending, and (I'm guessing) signals are + * processed in numeric order so the SIGTERM (signal 15 vs + * SIGSEGV being signal 11) is never handled. + * + * Run a waitpid loop until we get some kind of error. + * Hopefully, it's ECHILD, but there's not a lot we can do if + * it's something else. Tell os_kill_ptraced_process not to + * wait for the child to report its death because there's + * nothing reasonable to do if that fails. + */ + + while ((pid = waitpid(-1, NULL, WNOHANG)) > 0) + os_kill_ptraced_process(pid, 0); + abort(); } --