On Sat, 2013-08-31 at 02:39 +0200, Rafael J. Wysocki wrote: > 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. Agreed. The code looks good otherwise, and this is a nice cleanup. If it is OK to ignore the possible warning from the tool (which I do not know the rule here), feel free to add my ack to patch 2/3 and 3/3 as well. Thanks, -Toshi -- 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>