On Friday, August 30, 2013 06:23:19 PM Toshi Kani wrote: > On Thu, 2013-08-29 at 23:18 +0200, Rafael J. Wysocki wrote: > > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > > > Since all of the memory hotplug operations have to be carried out > > under device_hotplug_lock, they won't need to acquire pm_mutex if > > device_hotplug_lock is held around hibernation. > > > > For this reason, make the hibernation code acquire > > device_hotplug_lock after freezing user space processes and > > release it before thawing them. At the same tim drop the > > lock_system_sleep() and unlock_system_sleep() calls from > > lock_memory_hotplug() and unlock_memory_hotplug(), respectively. > > > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > --- > > kernel/power/hibernate.c | 4 ++++ > > kernel/power/user.c | 2 ++ > > mm/memory_hotplug.c | 4 ---- > > 3 files changed, 6 insertions(+), 4 deletions(-) > > > > Index: linux-pm/kernel/power/hibernate.c > > =================================================================== > > --- linux-pm.orig/kernel/power/hibernate.c > > +++ linux-pm/kernel/power/hibernate.c > > @@ -652,6 +652,7 @@ int hibernate(void) > > if (error) > > goto Exit; > > > > + lock_device_hotplug(); > > Since hibernate() can be called from sysfs, do you think the tool may > see this as a circular dependency with p_active again? This shouldn't > be a problem in practice, though. /sys/power/state isn't a device attribute even and is never removed, so it would be very sad and disappointing if lockdep reported that as a circular dependency. The deadlock is surely not possible here anyway. Thanks, Rafael -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>