Re: 2.6.29-rc3 circular locking dependency detected

[Mark McLoughlin <markmc@redhat.com>]

On Tue, 2009-02-03 at 12:47 +0200, Avi Kivity wrote:
> Mark McLoughlin wrote:

> > which lock already depends on the new lock.
> >
> > the existing dependency chain (in reverse order) is:
> >
> > -> #1 (&kvm->slots_lock){----}:
> >        [<ffffffff8106e9c1>] __lock_acquire+0xaab/0xc41
> >        [<ffffffff8106ebe4>] lock_acquire+0x8d/0xba
> >        [<ffffffff813826ae>] down_read+0x4b/0x7f
> >        [<ffffffffa0137ff2>] kvm_iommu_map_guest+0x62/0xb8 [kvm]
> >        [<ffffffffa01363ea>] kvm_vm_ioctl+0x3f4/0x7f1 [kvm]
> >        [<ffffffff810eac30>] vfs_ioctl+0x2a/0x78
> >        [<ffffffff810eb0e9>] do_vfs_ioctl+0x46b/0x4ab
> >        [<ffffffff810eb17e>] sys_ioctl+0x55/0x77
> >        [<ffffffff810112ba>] system_call_fastpath+0x16/0x1b
> >        [<ffffffffffffffff>] 0xffffffffffffffff
> >   
> 
> I think taking slots_lock in kvm_vm_ioctl_assign_device() (and dropping 
> it from kvm_iommu_map_guest) should suffice, no?

Just from a quick look, that seems right - also need to remove the
locking from kvm_iommu_unmap_memslots()

Cheers,
Mark.