Re: [Patch v2] sysfs: add lockdep class support to s_active

Eric W. Biederman
2010-02-05T09:01:53Z

Amerigo Wang <amwang@redhat.com> writes:

> Recently we met a lockdep warning from sysfs during s2ram or cpu hotplug.
> As reported by several people, it is something like:

The interesting case is the cpu hotplug is actually a problem. It isn't
useful to get a complaint about the non-problems code paths triggered
by pm. However my earlier review spotted a real deadlock case. Where
in one of the sysfs attributes we iterate over the list of online cpus
and that appeared to an attribute that removing a cpu would remove
from sysfs...

Eric