* Re: suspicious RCU usage with kvm_pr
[not found] <CAOJe8K3mu6M48wGAMMQNXPDrkzk+z4j5yzcJ7eRfex0FWcZsQA@mail.gmail.com>
@ 2015-09-16 10:16 ` Thomas Huth
2015-09-16 10:59 ` Denis Kirjanov
0 siblings, 1 reply; 4+ messages in thread
From: Thomas Huth @ 2015-09-16 10:16 UTC (permalink / raw)
To: Denis Kirjanov, kvm-ppc; +Cc: linuxppc-dev, kvm
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?
Thomas
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: suspicious RCU usage with kvm_pr
2015-09-16 10:16 ` suspicious RCU usage with kvm_pr Thomas Huth
@ 2015-09-16 10:59 ` Denis Kirjanov
2015-09-18 13:13 ` Thomas Huth
0 siblings, 1 reply; 4+ messages in thread
From: Denis Kirjanov @ 2015-09-16 10:59 UTC (permalink / raw)
To: Thomas Huth; +Cc: kvm-ppc, linuxppc-dev, kvm
On 9/16/15, Thomas Huth <thuth@redhat.com> 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.
Thanks
>
> Thomas
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: suspicious RCU usage with kvm_pr
2015-09-16 10:59 ` Denis Kirjanov
@ 2015-09-18 13:13 ` Thomas Huth
2015-09-18 19:54 ` Denis Kirjanov
0 siblings, 1 reply; 4+ messages in thread
From: Thomas Huth @ 2015-09-18 13:13 UTC (permalink / raw)
To: Denis Kirjanov; +Cc: kvm-ppc, linuxppc-dev, kvm
On 16/09/15 12:59, Denis Kirjanov wrote:
> On 9/16/15, Thomas Huth <thuth@redhat.com> 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
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: suspicious RCU usage with kvm_pr
2015-09-18 13:13 ` Thomas Huth
@ 2015-09-18 19:54 ` Denis Kirjanov
0 siblings, 0 replies; 4+ messages in thread
From: Denis Kirjanov @ 2015-09-18 19:54 UTC (permalink / raw)
To: Thomas Huth; +Cc: kvm-ppc, linuxppc-dev, kvm
On 9/18/15, Thomas Huth <thuth@redhat.com> wrote:
> On 16/09/15 12:59, Denis Kirjanov wrote:
>> On 9/16/15, Thomas Huth <thuth@redhat.com> 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!
It fixed the issue. Thanks!
>
> Thomas
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2015-09-18 19:54 UTC | newest]
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[not found] <CAOJe8K3mu6M48wGAMMQNXPDrkzk+z4j5yzcJ7eRfex0FWcZsQA@mail.gmail.com>
2015-09-16 10:16 ` suspicious RCU usage with kvm_pr Thomas Huth
2015-09-16 10:59 ` Denis Kirjanov
2015-09-18 13:13 ` Thomas Huth
2015-09-18 19:54 ` Denis Kirjanov
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