Commit 61a734d3 authored Aug 18, 2014 by Ross Lagerwall Committed by David Vrabel Sep 02, 2014

xen/manage: Always freeze/thaw processes when suspend/resuming



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 <ross.lagerwall@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: stable@vger.kernel.org

parent 7d951f3c

drivers/xen/manage.c

+0 −7

Original line number	Diff line number	Diff line
		@@ -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 */

Admin message