[ofa-general] Re: lockdep question (was Re: IPoIB caused a kernel: BUG: softlockup detected on CPU#0!)

[Michael S. Tsirkin]

> Quoting Ingo Molnar <mingo at elte.hu>:
> Subject: Re: lockdep question (was Re: IPoIB caused a kernel: BUG: softlockup detected on CPU#0!)
> 
> 
> * Michael S. Tsirkin <mst at mellanox.co.il> wrote:
> 
> > > So either there are other sites that instanciate those objects and
> > > forget about the lock init, or the object is corrupted (use after free?)
> > 
> > OK, thanks for the hint. So I added this:
> 
> > And sure enough it triggers:
> > 
> > [  858.503010] ipoib_neigh_destructor lock c0687880 wrong type 772 !!!!!!!!!!
> 
> could you turn on CONFIG_SLAB_DEBUG as well?
> 
> that should catch certain types of use-after-free accesses, and lockdep 
> will also warn if a still locked object is freed.

Hmm, no, this does not look like use-after-free.
I enabled CONFIG_SLAB_DEBUG, and I still see the same message, so
the memory was not overwritten by slab debugger.


-- 
MST