Messages in this thread Patch in this message | | | Date | Sun, 19 Aug 2007 13:55:13 +0300 | From | Avi Kivity <> | Subject | Re: WARNING: at arch/x86_64/kernel/smp.c:379 smp_call_function_single() |
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Avi Kivity wrote: > Paolo Ornati wrote: >> On Fri, 10 Aug 2007 14:04:33 +0200 >> "Michal Piotrowski" <michal.k.k.piotrowski@gmail.com> wrote: >> >> >>>> [ 756.707601] Disabling non-boot CPUs ... >>>> [ 756.712034] kvm: disabling virtualization on CPU1 >>>> [ 756.712037] WARNING: at arch/x86_64/kernel/smp.c:379 >>>> smp_call_function_single() >>>> [ 756.712039] >>>> [ 756.712039] Call Trace: >>>> [ 756.712046] [<ffffffff8021d159>] >>>> smp_call_function_single+0x119/0x120 >>>> [ 756.712050] [<ffffffff80542169>] thread_return+0x1bf/0x626 >>>> [ 756.712054] [<ffffffff80234b5b>] sys_sched_yield+0x2b/0x80 >>>> [ 756.712057] [<ffffffff8043684b>] kvm_cpu_hotplug+0x4b/0xa0 >>>> [ 756.712060] [<ffffffff80247c83>] notifier_call_chain+0x53/0x80 >>>> [ 756.712062] [<ffffffff80247d09>] >>>> __raw_notifier_call_chain+0x9/0x10 >>>> [ 756.712065] [<ffffffff80247d21>] raw_notifier_call_chain+0x11/0x20 >>>> [ 756.712068] [<ffffffff8026184b>] take_cpu_down+0x1b/0x30 >>>> [ 756.712071] [<ffffffff802699d2>] do_stop+0xd2/0x150 >>>> [ 756.712073] [<ffffffff80269900>] do_stop+0x0/0x150 >>>> [ 756.712076] [<ffffffff8024f84d>] kthread+0x4d/0x80 >>>> [ 756.712079] [<ffffffff8020cb28>] child_rip+0xa/0x12 >>>> [ 756.712081] [<ffffffff8020c23c>] restore_args+0x0/0x30 >>>> [ 756.712084] [<ffffffff8024f800>] kthread+0x0/0x80 >>>> [ 756.712086] [<ffffffff8020cb1e>] child_rip+0x0/0x12 >>>> [ 756.712087] >>>> [ 756.815693] CPU 1 is now offline >>>> [ 756.815697] lockdep: not fixing up alternatives. >>>> [ 756.819276] CPU1 is down >>>> >>>> >>> Added to KR list, thanks for the report. >>> >> >> >> I've bisected it down to this commit: >> >> cec9ad279b66793bee0b5009b7ca311060061efd >> >> KVM: Use CPU_DYING for disabling virtualization >> Only at the CPU_DYING stage can we be sure that no user >> process will >> be scheduled onto the cpu and oops when trying to use virtualization >> extensions. >> >> > > Thanks. I'll have a go at it. > >
Sorry about the delay -- here is the fairly simple patch. A Tested-by: would be appreciated.
-- error compiling committee.c: too many arguments to function
From a8c346b28695b938018f4bafd458f6d3e70c36e3 Mon Sep 17 00:00:00 2001 From: Avi Kivity <avi@qumranet.com> Date: Sun, 19 Aug 2007 13:51:00 +0300 Subject: [PATCH] KVM: Avoid calling smp_call_function_single() with interrupts disabled
When taking a cpu down, we need to hardware_disable() it. Unfortunately, the CPU_DYING notifier is called with interrupts disabled, which means we can't use smp_call_function_single(). Fortunately, the CPU_DYING notifier is always called on the dying cpu, so we don't need to use the function at all and can simply call hardware_disable() directly.
Signed-off-by: Avi Kivity <avi@qumranet.com> --- drivers/kvm/kvm_main.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c index 9685609..cd05579 100644 --- a/drivers/kvm/kvm_main.c +++ b/drivers/kvm/kvm_main.c @@ -2974,6 +2974,10 @@ static int kvm_cpu_hotplug(struct notifier_block *notifier, unsigned long val, switch (val) { case CPU_DYING: case CPU_DYING_FROZEN: + printk(KERN_INFO "kvm: disabling virtualization on CPU%d\n", + cpu); + hardware_disable(NULL); + break; case CPU_UP_CANCELED: case CPU_UP_CANCELED_FROZEN: printk(KERN_INFO "kvm: disabling virtualization on CPU%d\n", -- 1.5.2.4
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