Re: [PATCH 4/10] KVM: fix rcu usage in init_rmode_* functions

From: Xiao Guangrong
Date: Sun Mar 06 2011 - 21:03:41 EST


On 03/04/2011 07:43 PM, Jan Kiszka wrote:
> On 2011-03-04 11:58, Xiao Guangrong wrote:
>> fix:
>> [ 3494.671786] stack backtrace:
>> [ 3494.671789] Pid: 10527, comm: qemu-system-x86 Not tainted 2.6.38-rc6+ #23
>> [ 3494.671790] Call Trace:
>> [ 3494.671796] [<ffffffff8107d15f>] ? lockdep_rcu_dereference+0x9d/0xa5
>> [ 3494.671826] [<ffffffffa03498be>] ? kvm_memslots+0x6b/0x73 [kvm]
>> [ 3494.671834] [<ffffffffa03499be>] ? gfn_to_memslot+0x16/0x4f [kvm]
>> [ 3494.671843] [<ffffffffa0349a0d>] ? gfn_to_hva+0x16/0x27 [kvm]
>> [ 3494.671851] [<ffffffffa034c1c4>] ? kvm_write_guest_page+0x31/0x83 [kvm]
>> [ 3494.671861] [<ffffffffa034c230>] ? kvm_clear_guest_page+0x1a/0x1c [kvm]
>> [ 3494.671867] [<ffffffffa015e321>] ? vmx_set_tss_addr+0x83/0x122 [kvm_intel]
>>
>> and:
>> [ 8328.789599] stack backtrace:
>> [ 8328.789601] Pid: 18736, comm: qemu-system-x86 Not tainted 2.6.38-rc6+ #23
>> [ 8328.789603] Call Trace:
>> [ 8328.789609] [<ffffffff8107d15f>] ? lockdep_rcu_dereference+0x9d/0xa5
>> [ 8328.789621] [<ffffffffa03988be>] ? kvm_memslots+0x6b/0x73 [kvm]
>> [ 8328.789628] [<ffffffffa03989be>] ? gfn_to_memslot+0x16/0x4f [kvm]
>> [ 8328.789635] [<ffffffffa0398a0d>] ? gfn_to_hva+0x16/0x27 [kvm]
>> [ 8328.789643] [<ffffffffa039b1c4>] ? kvm_write_guest_page+0x31/0x83 [kvm]
>> [ 8328.789699] [<ffffffffa039b230>] ? kvm_clear_guest_page+0x1a/0x1c [kvm]
>> [ 8328.789713] [<ffffffffa0206d0e>] ? vmx_create_vcpu+0x316/0x3c8 [kvm_intel]
>>
>> Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxx>
>> ---
>> arch/x86/kvm/vmx.c | 10 +++++++---
>> 1 files changed, 7 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> index e2b8c6b..d871ced 100644
>> --- a/arch/x86/kvm/vmx.c
>> +++ b/arch/x86/kvm/vmx.c
>> @@ -2399,9 +2399,10 @@ static int init_rmode_tss(struct kvm *kvm)
>> {
>> gfn_t fn = rmode_tss_base(kvm) >> PAGE_SHIFT;
>
> I bet you also wanted to remove this initialization.
>

Ouch, thank you for reminding me of that!
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