Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755271AbaJCVpK (ORCPT ); Fri, 3 Oct 2014 17:45:10 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:45300 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756058AbaJCVnV (ORCPT ); Fri, 3 Oct 2014 17:43:21 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ross Lagerwall , David Vrabel Subject: [PATCH 3.16 213/357] xen/manage: Always freeze/thaw processes when suspend/resuming Date: Fri, 3 Oct 2014 14:29:59 -0700 Message-Id: <20141003212939.927323093@linuxfoundation.org> X-Mailer: git-send-email 2.1.2 In-Reply-To: <20141003212933.458851516@linuxfoundation.org> References: <20141003212933.458851516@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ross Lagerwall commit 61a734d305e16944b42730ef582a7171dc733321 upstream. Always freeze processes when suspending and thaw processes when resuming to prevent a race noticeable with HVM guests. This prevents a deadlock where the khubd kthread (which is designed to be freezable) acquires a usb device lock and then tries to allocate memory which requires the disk which hasn't been resumed yet. Meanwhile, the xenwatch thread deadlocks waiting for the usb device lock. Freezing processes fixes this because the khubd thread is only thawed after the xenwatch thread finishes resuming all the devices. Signed-off-by: Ross Lagerwall Signed-off-by: David Vrabel Signed-off-by: Greg Kroah-Hartman --- drivers/xen/manage.c | 7 ------- 1 file changed, 7 deletions(-) --- a/drivers/xen/manage.c +++ b/drivers/xen/manage.c @@ -103,16 +103,11 @@ static void do_suspend(void) shutting_down = SHUTDOWN_SUSPEND; -#ifdef CONFIG_PREEMPT - /* If the kernel is preemptible, we need to freeze all the processes - to prevent them from being in the middle of a pagetable update - during suspend. */ err = freeze_processes(); if (err) { pr_err("%s: freeze failed %d\n", __func__, err); goto out; } -#endif err = dpm_suspend_start(PMSG_FREEZE); if (err) { @@ -157,10 +152,8 @@ out_resume: dpm_resume_end(si.cancelled ? PMSG_THAW : PMSG_RESTORE); out_thaw: -#ifdef CONFIG_PREEMPT thaw_processes(); out: -#endif shutting_down = SHUTDOWN_INVALID; } #endif /* CONFIG_HIBERNATE_CALLBACKS */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/