Mark McLoughlin wrote:
Hi,
Just saw this when starting a guest with an assigned device.
Cheers,
Mark.
=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.29-0.74.rc3.git3.fc11.x86_64 #1
-------------------------------------------------------
qemu-kvm/3706 is trying to acquire lock:
(&kvm->lock){--..}, at: [<ffffffffa013a25f>] kvm_emulate_pio+0x1ab/0x1ff [kvm]
but task is already holding lock:
(&kvm->slots_lock){----}, at: [<ffffffffa013c4c0>] kvm_arch_vcpu_ioctl_run+0x49
7/0x73a [kvm]
This is the expected nesting. kvm->slots_lock is outer to kvm->lock.
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&kvm->slots_lock){----}:
[<ffffffff8106e9c1>] __lock_acquire+0xaab/0xc41
[<ffffffff8106ebe4>] lock_acquire+0x8d/0xba
[<ffffffff813826ae>] down_read+0x4b/0x7f
[<ffffffffa0137ff2>] kvm_iommu_map_guest+0x62/0xb8 [kvm]
[<ffffffffa01363ea>] kvm_vm_ioctl+0x3f4/0x7f1 [kvm]
[<ffffffff810eac30>] vfs_ioctl+0x2a/0x78
[<ffffffff810eb0e9>] do_vfs_ioctl+0x46b/0x4ab
[<ffffffff810eb17e>] sys_ioctl+0x55/0x77
[<ffffffff810112ba>] system_call_fastpath+0x16/0x1b
[<ffffffffffffffff>] 0xffffffffffffffff
I think taking slots_lock in kvm_vm_ioctl_assign_device() (and dropping
it from kvm_iommu_map_guest) should suffice, no?
--
error compiling committee.c: too many arguments to function
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