From: Lai Jiangshan <laijs@cn.fujitsu.com>
To: Avi Kivity <avi@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
LKML <linux-kernel@vger.kernel.org>,
kvm@vger.kernel.org
Subject: [BUG] kvm: dereference srcu-protected pointer without srcu_read_lock() held
Date: Mon, 19 Apr 2010 17:58:53 +0800 [thread overview]
Message-ID: <4BCC295D.1040807@cn.fujitsu.com> (raw)
In-Reply-To: <4BCC2543.7050104@cn.fujitsu.com>
Applied the patch I just sent and let CONFIG_PROVE_RCU=y,
we can got the following dmesg. And we found that it is
because some codes in KVM dereferences srcu-protected pointer without
srcu_read_lock() held or update-side lock held.
It is not hard to fix, the problem is that:
Where is the most proper place to put a srcu_read_lock()?
I can not determine the answer, so I report this bug
instead of fixing it.
Thanks.
Lai.
Reported-by: Lai Jiangshan <laijs@cn.fujitsu.com>
===================================================
[ INFO: suspicious rcu_dereference_check() usage. ]
---------------------------------------------------
arch/x86/kvm/x86.h:72 invoked rcu_dereference_check() without protection!
other info that might help us debug this:
rcu_scheduler_active = 1, debug_locks = 0
1 lock held by qemu-system-x86/3027:
#0: (&vcpu->mutex){+.+.+.}, at: [<ffffffffa011b6ff>] vcpu_load+0x1a/0x66 [kvm]
stack backtrace:
Pid: 3027, comm: qemu-system-x86 Not tainted 2.6.34-rc4-tip-01028-g939eab1-dirty #28
Call Trace:
[<ffffffff8106c59e>] lockdep_rcu_dereference+0xaa/0xb3
[<ffffffffa0123654>] unalias_gfn_instantiation+0x56/0xaf [kvm]
[<ffffffffa01198de>] gfn_to_hva+0x14/0x4c [kvm]
[<ffffffffa01199ca>] kvm_write_guest_page+0x2a/0x7f [kvm]
[<ffffffffa0119afb>] kvm_write_guest+0x41/0x83 [kvm]
[<ffffffffa01243b5>] kvm_write_guest_virt+0x78/0xa1 [kvm]
[<ffffffffa012479a>] pio_copy_data+0x46/0x75 [kvm]
[<ffffffff81385a0f>] ? sub_preempt_count+0x9/0x83
[<ffffffffa012485a>] complete_pio+0x91/0x1b9 [kvm]
[<ffffffffa0128728>] kvm_arch_vcpu_ioctl_run+0x93/0xd2b [kvm]
[<ffffffffa0128f7a>] ? kvm_arch_vcpu_ioctl_run+0x8e5/0xd2b [kvm]
[<ffffffff8106e590>] ? __lock_acquire+0x7b4/0x16d5
[<ffffffffa0117ecd>] kvm_vcpu_ioctl+0x103/0x97b [kvm]
[<ffffffffa011b15b>] ? kvm_vm_ioctl+0x364/0x38d [kvm]
[<ffffffff810e6b5e>] ? fget_light+0xf1/0x241
[<ffffffff810f3587>] vfs_ioctl+0x32/0xa6
[<ffffffff810f3b19>] do_vfs_ioctl+0x495/0x4db
[<ffffffff810e6c9e>] ? fget_light+0x231/0x241
[<ffffffff810e6b5e>] ? fget_light+0xf1/0x241
[<ffffffff810f3ba6>] sys_ioctl+0x47/0x6a
[<ffffffff810021db>] system_call_fastpath+0x16/0x1b
next prev parent reply other threads:[~2010-04-19 9:59 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-19 9:41 [PATCH] kvm: use the correct RCU API Lai Jiangshan
2010-04-19 9:49 ` Avi Kivity
2010-04-19 23:35 ` Paul E. McKenney
2010-04-20 2:09 ` Lai Jiangshan
2010-04-20 18:42 ` Paul E. McKenney
2010-04-19 9:58 ` Lai Jiangshan [this message]
2010-04-19 10:08 ` [BUG] kvm: dereference srcu-protected pointer without srcu_read_lock() held Avi Kivity
2010-04-20 1:45 ` Marcelo Tosatti
2010-04-20 6:29 ` Lai Jiangshan
2010-04-20 22:21 ` Paul E. McKenney
2010-04-21 8:17 ` Avi Kivity
2010-04-21 14:36 ` Paul E. McKenney
2010-04-20 21:55 ` [PATCH] kvm: use the correct RCU API Paul E. McKenney
2010-04-21 8:22 ` Avi Kivity
2010-04-21 8:22 ` Avi Kivity
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