From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ross Lagerwall Subject: [PATCH] xen/manage: Always freeze/thaw processes when suspend/resuming Date: Mon, 18 Aug 2014 10:41:36 +0100 Message-ID: <1408354896-30770-1-git-send-email-ross.lagerwall@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1XJJRo-00045R-59 for xen-devel@lists.xenproject.org; Mon, 18 Aug 2014 09:41:52 +0000 List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: xen-devel@lists.xenproject.org Cc: Ross Lagerwall , Boris Ostrovsky , David Vrabel List-Id: xen-devel@lists.xenproject.org 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 --- drivers/xen/manage.c | 7 ------- 1 file changed, 7 deletions(-) diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c index 5f1e1f3..f8bb36f 100644 --- 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 */ -- 1.9.3