Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752136AbaKAWkm (ORCPT ); Sat, 1 Nov 2014 18:40:42 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:60372 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751860AbaKAWjf (ORCPT ); Sat, 1 Nov 2014 18:39:35 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "David Vrabel" , "Ross Lagerwall" Date: Sat, 01 Nov 2014 22:28:03 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 021/102] xen/manage: Always freeze/thaw processes when suspend/resuming In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.64-rc1 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 [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- drivers/xen/manage.c | 7 ------- 1 file changed, 7 deletions(-) --- a/drivers/xen/manage.c +++ b/drivers/xen/manage.c @@ -108,16 +108,11 @@ 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) { printk(KERN_ERR "xen suspend: freeze failed %d\n", err); goto out; } -#endif err = dpm_suspend_start(PMSG_FREEZE); if (err) { @@ -172,10 +167,8 @@ out_resume: clock_was_set(); 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/