On 16/09/15 12:59, Denis Kirjanov wrote:
> On 9/16/15, Thomas Huth <thuth@xxxxxxxxxx> wrote:
>> On 16/09/15 10:51, Denis Kirjanov wrote:
>>> Hi,
>>>
>>> I see the following trace on qemu startup (ps700 blade):
>>>
>>> v4.2-11169-g64d1def
>>>
>>>
>>> [ 143.369638] ===============================
>>> [ 143.369640] [ INFO: suspicious RCU usage. ]
>>> [ 143.369643] 4.2.0-11169-g64d1def #10 Tainted: G S
>>> [ 143.369645] -------------------------------
>>> [ 143.369647] arch/powerpc/kvm/../../../virt/kvm/kvm_main.c:3310
>>> suspicious rcu_dereference_check() usage!
>>> [ 143.369649]
>>> other info that might help us debug this:
>>>
>>> [ 143.369652]
>>> rcu_scheduler_active = 1, debug_locks = 1
>>> [ 143.369655] 1 lock held by qemu-system-ppc/2292:
>>> [ 143.369656] #0: (&vcpu->mutex){+.+.+.}, at: [<d000000004225bac>]
>>> .vcpu_load+0x2c/0xb0 [kvm]
>>> [ 143.369672]
>>> stack backtrace:
>>> [ 143.369675] CPU: 12 PID: 2292 Comm: qemu-system-ppc Tainted: G S
>>> 4.2.0-11169-g64d1def #10
>>> [ 143.369677] Call Trace:
>>> [ 143.369682] [c0000001d08bf200] [c000000000816dd0]
>>> .dump_stack+0x98/0xd4 (unreliable)
>>> [ 143.369687] [c0000001d08bf280] [c0000000000f7058]
>>> .lockdep_rcu_suspicious+0x108/0x170
>>> [ 143.369696] [c0000001d08bf310] [d0000000042296d8]
>>> .kvm_io_bus_read+0x1d8/0x220 [kvm]
>>> [ 143.369705] [c0000001d08bf3c0] [d00000000422f980]
>>> .kvmppc_h_logical_ci_load+0x60/0xe0 [kvm]
>>
>> Could it be that we need to srcu_read_lock(&vcpu->kvm->srcu) before
>> calling the kvm_io_bus_read/write() function in the
>> kvmppc_h_logical_ci_load/store() function?
>
> I haven't had time to dig into this. I'll try it.
FYI, I had the same problem with kvm_hv, so I tried to come up with a patch:
https://patchwork.ozlabs.org/patch/519143/
Sorry, forgot to CC: you there, but it would be great if you could give
it a try!
Thomas
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
