On Tue, Jul 18, 2017 at 02:16:06PM +0200, Peter Zijlstra wrote: > On Tue, Jul 18, 2017 at 09:03:47AM -0300, Marcelo Tosatti wrote: > > > > wait_lock for mmu_lock, being allocated in kmalloc memory, > > can't be tracked by LOCKDEP. > > > > Disable LOCKDEP verification for it. > > > > Fixes > > > > INFO: trying to register non-static key. > > the code is fine but needs lockdep annotation. > > turning off the locking correctness validator. > > CPU: 0 PID: 12386 Comm: qemu-kvm Not tainted 3.10.0-631.rt56.546.el7.x86_64.debug #1 > > Hardware name: To be filled by O.E.M. To be filled by O.E.M./PMH61ML, BIOS 4.6.4 07/14/2011 > > 0000000000000002 00000000ee340fa8 ffff88008e2d7bc0 ffffffffa57534fc > > ffff88008e2d7bd0 ffffffffa574ce9f ffff88008e2d7c50 ffffffffa510e565 > > ffff88008e2d7bf8 00000001a50cf83d 0000000000000000 ffff880000000000 > > Call Trace: > > [<ffffffffa57534fc>] dump_stack+0x19/0x1b > > [<ffffffffa574ce9f>] register_lock_class.part.27+0x38/0x3c > > [<ffffffffa510e565>] __lock_acquire+0xcc5/0xdc0 > > [<ffffffffa510efb2>] lock_acquire+0xb2/0x230 > > [<ffffffffa5759ccd>] ? rt_spin_lock_slowlock+0x6d/0x3c0 > > [<ffffffffa575c5f0>] _raw_spin_lock_irqsave+0x70/0xc0 > > [<ffffffffa5759ccd>] ? rt_spin_lock_slowlock+0x6d/0x3c0 > > [<ffffffffa5759ccd>] rt_spin_lock_slowlock+0x6d/0x3c0 > > [<ffffffffa575b7ac>] rt_spin_lock+0x2c/0x60 > > [<ffffffffc09b387f>] kvm_page_track_register_notifier+0x1f/0x60 [kvm] > > [<ffffffffc099a8eb>] kvm_mmu_init_vm+0x2b/0x30 [kvm] > > [<ffffffffc0987e04>] kvm_arch_init_vm+0x264/0x290 [kvm] > > [<ffffffffc096a14e>] kvm_dev_ioctl+0xde/0x740 [kvm] > > [<ffffffffa5250d45>] do_vfs_ioctl+0x365/0x5b0 > > [<ffffffffa5251031>] SyS_ioctl+0xa1/0xc0 > > [<ffffffffa57656ed>] tracesys+0xdd/0xe2 > > --------------------------- > > | preempt count: 00000001 ] > > | 1-level deep critical section nesting: > > ---------------------------------------- > > .. [<ffffffffa575c5cd>] .... _raw_spin_lock_irqsave+0x4d/0xc0 > > .....[<ffffffffa5759ccd>] .. ( <= rt_spin_lock_slowlock+0x6d/0x3c0) > > > > > > Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx> > > > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > > index 7e80f62..6375db8 100644 > > --- a/virt/kvm/kvm_main.c > > +++ b/virt/kvm/kvm_main.c > > @@ -613,6 +613,8 @@ static struct kvm *kvm_create_vm(unsigned long type) > > return ERR_PTR(-ENOMEM); > > > > spin_lock_init(&kvm->mmu_lock); > > + > > + lockdep_set_novalidate_class(&kvm->mmu_lock.lock.wait_lock); > > mmgrab(current->mm); > > kvm->mm = current->mm; > > kvm_eventfd_init(kvm); > > This doesn't make sense... It looks like a spin_lock_init() is missing, > at which point it'll try and use the lock address itself and then bails > because that is in dynamic memory. Do you see the spin_lock_init just above, after "return PTR_ERR(-ENOMEM)"... That should take care of wait_lock i suppose. "struct kvm" (which contains the mmu_lock spinlock) is allocated with kmalloc, can LOCKDEP handle spinlocks in kmalloc'ed memory? > That doesn't mean you cannot initialize it properly. > > And using novalidate for this is absolutely bonkers. I imagined so, not entirely sure what is the proper LOCKDEP annotation in this case...
