On Thu, Sep 28, 2017 at 04:51:46PM -0700, Govindarajulu Varadarajan wrote: > On Thu, 28 Sep 2017, Peter Zijlstra wrote: > > >On Wed, Sep 27, 2017 at 02:42:20PM -0700, Govindarajulu Varadarajan wrote: > >>Make MAX_LOCK_DEPTH configurable. It is set to 48 right now. Number of > >>VFs under a PCI pf bus can exceed 48 and this disables lockdep. > >> > >>lockdep currently allows max of 63 held_locks. > > > >But why a config knob? Why not just raise the number to 64 > >unconditionally? And is that sufficient; you only state 48 is > >insufficient, you don't actually state the VF limit. > > > > I did not want to change the default configuration for everyone. > > I will change it 63 unconditionally in v2 and resubmit the series. I'm not happy about having to increase MAX_LOCK_DEPTH based on a number of VFs. I haven't had time to look at the locking strategy you're proposing, but it just doesn't feel right to have to take 50+ locks for one operation. Bjorn
