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Commit 61a734d3 authored by Ross Lagerwall's avatar Ross Lagerwall Committed by David Vrabel
Browse files

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: default avatarRoss Lagerwall <ross.lagerwall@citrix.com>
Signed-off-by: default avatarDavid 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 @@ static void do_suspend(void) 
	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 */