linux-kernel - Re: [PATCH] kvm: use the correct RCU API

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Message-ID: <4BCEB5DD.1000701@redhat.com>
Date:	Wed, 21 Apr 2010 11:22:53 +0300
From:	Avi Kivity <avi@...hat.com>
To:	paulmck@...ux.vnet.ibm.com
CC:	Lai Jiangshan <laijs@...fujitsu.com>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Ingo Molnar <mingo@...e.hu>,
	LKML <linux-kernel@...r.kernel.org>, kvm@...r.kernel.org
Subject: Re: [PATCH] kvm: use the correct RCU API

On 04/21/2010 12:55 AM, Paul E. McKenney wrote:
> On Mon, Apr 19, 2010 at 05:41:23PM +0800, Lai Jiangshan wrote:
>    
>> The RCU/SRCU API have already changed for proving RCU usage.
>>
>> I got the following dmesg when PROVE_RCU=y because we used incorrect API.
>> This patch coverts rcu_deference() to srcu_dereference() or family API.
>>
>> ===================================================
>> [ INFO: suspicious rcu_dereference_check() usage. ]
>> ---------------------------------------------------
>> arch/x86/kvm/mmu.c:3020 invoked rcu_dereference_check() without protection!
>>
>> other info that might help us debug this:
>>
>>
>> rcu_scheduler_active = 1, debug_locks = 0
>> 2 locks held by qemu-system-x86/8550:
>>   #0:  (&kvm->slots_lock){+.+.+.}, at: [<ffffffffa011a6ac>] kvm_set_memory_region+0x29/0x50 [kvm]
>>   #1:  (&(&kvm->mmu_lock)->rlock){+.+...}, at: [<ffffffffa012262d>] kvm_arch_commit_memory_region+0xa6/0xe2 [kvm]
>>
>> stack backtrace:
>> Pid: 8550, comm: qemu-system-x86 Not tainted 2.6.34-rc4-tip-01028-g939eab1 #27
>> Call Trace:
>>   [<ffffffff8106c59e>] lockdep_rcu_dereference+0xaa/0xb3
>>   [<ffffffffa012f6c1>] kvm_mmu_calculate_mmu_pages+0x44/0x7d [kvm]
>>   [<ffffffffa012263e>] kvm_arch_commit_memory_region+0xb7/0xe2 [kvm]
>>   [<ffffffffa011a5d7>] __kvm_set_memory_region+0x636/0x6e2 [kvm]
>>   [<ffffffffa011a6ba>] kvm_set_memory_region+0x37/0x50 [kvm]
>>   [<ffffffffa015e956>] vmx_set_tss_addr+0x46/0x5a [kvm_intel]
>>   [<ffffffffa0126592>] kvm_arch_vm_ioctl+0x17a/0xcf8 [kvm]
>>   [<ffffffff810a8692>] ? unlock_page+0x27/0x2c
>>   [<ffffffff810bf879>] ? __do_fault+0x3a9/0x3e1
>>   [<ffffffffa011b12f>] kvm_vm_ioctl+0x364/0x38d [kvm]
>>   [<ffffffff81060cfa>] ? up_read+0x23/0x3d
>>   [<ffffffff810f3587>] vfs_ioctl+0x32/0xa6
>>   [<ffffffff810f3b19>] do_vfs_ioctl+0x495/0x4db
>>   [<ffffffff810e6b2f>] ? fget_light+0xc2/0x241
>>   [<ffffffff810e416c>] ? do_sys_open+0x104/0x116
>>   [<ffffffff81382d6d>] ? retint_swapgs+0xe/0x13
>>   [<ffffffff810f3ba6>] sys_ioctl+0x47/0x6a
>>   [<ffffffff810021db>] system_call_fastpath+0x16/0x1b
>>      
> I have queued this one up, thank you, Lai!
>
>    

I'd like this to go through kvm.git as well.

-- 
error compiling committee.c: too many arguments to function

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