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    SubjectRe: [RFC][PATCH 7/7] lockdep: spin_lock_nest_lock()
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    On Mon, 2008-08-04 at 18:26 +0200, Andrea Arcangeli wrote:
    > On Mon, Aug 04, 2008 at 04:56:03PM +0200, Peter Zijlstra wrote:
    > > My guess is that the kvm thing attaches before there are any vma, and
    > > leaves after all the vma are gone. So it would never actually trigger.
    >
    > Yes, lockdep seems to be fine with kvm in kernel mainline in my
    > current and past testing. Andrew asked me to check this long ago.
    >
    > vmx ~ # zgrep LOCKDEP /proc/config.gz
    > CONFIG_LOCKDEP_SUPPORT=y
    > CONFIG_LOCKDEP=y
    > CONFIG_DEBUG_LOCKDEP=y

    You also need CONFIG_PROVE_LOCKING, but I'll assume that's set too.

    > CPA self-test:
    > 4k 26112 large 1997 gb 0 x 2652[ffff880000000000-ffff8800bffff000]
    > miss 262144
    > 4k 186880 large 1683 gb 0 x 43021[ffff880000000000-ffff8800bffff000]
    > miss 262144
    > 4k 186880 large 1683 gb 0 x 43021[ffff880000000000-ffff8800bffff000]
    > miss 262144
    > ok.
    > loaded kvm module ()
    > apic write: bad size=1 fee00030
    > Ignoring de-assert INIT to vcpu 0
    > Ignoring de-assert INIT to vcpu 0
    > kvm: emulating exchange as write
    > apic write: bad size=1 fee00030
    > Ignoring de-assert INIT to vcpu 0
    > Ignoring de-assert INIT to vcpu 0
    > apic write: bad size=1 fee00030
    > Ignoring de-assert INIT to vcpu 0
    > Ignoring de-assert INIT to vcpu 0
    > apic write: bad size=1 fee00030
    > Ignoring de-assert INIT to vcpu 0
    > apic write: bad size=1 fee00030
    > Ignoring de-assert INIT to vcpu 0
    > apic write: bad size=1 fee00030
    > Ignoring de-assert INIT to vcpu 0
    > Ignoring de-assert INIT to vcpu 0
    > Ignoring de-assert INIT to vcpu 0
    >
    > I can't see lockdep errors in dmesg starting one more multiple VM in a
    > loop (all run on a quadcore).

    Dave Jones just handed me:

    https://bugzilla.redhat.com/show_bug.cgi?id=457779


    > GRU is likely the same.
    >
    > The only real place where lockdep is unusable in my experience is
    > preempt-RT, it grinds it to an halt during boot on 8-way before
    > reaching the shell.

    David Miller just did a patch that might fix that.



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