segfault at start with latest qemu-kvm.git

segfault at start with latest qemu-kvm.git

[David S. Ahern]

With latest qemu-kvm.git I am getting a segfault at start:

/tmp/qemu-kvm-test/bin/qemu-system-x86_64 -m 1024 -smp 2 \
  -drive file=/images/f12-x86_64.img,if=virtio,cache=none,boot=on

kvm_create_vcpu: Invalid argument
Segmentation fault (core dumped)


git bisect points to:

Bisecting: 0 revisions left to test after this (roughly 0 steps)
[52b03dd70261934688cb00768c4b1e404716a337] qemu-kvm: Move
kvm_set_boot_cpu_id


$ git show
commit 7811d4e8ec057d25db68f900be1f09a142faca49
Author: Marcelo Tosatti <mtosatti@redhat.com>
Date:   Mon Mar 1 21:36:31 2010 -0300


If I manually back out the patch it will boot fine.

-- 
David

Re: segfault at start with latest qemu-kvm.git

[Jan Kiszka]

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David S. Ahern wrote:
> With latest qemu-kvm.git I am getting a segfault at start:
> 
> /tmp/qemu-kvm-test/bin/qemu-system-x86_64 -m 1024 -smp 2 \
>   -drive file=/images/f12-x86_64.img,if=virtio,cache=none,boot=on
> 
> kvm_create_vcpu: Invalid argument
> Segmentation fault (core dumped)
> 
> 
> git bisect points to:
> 
> Bisecting: 0 revisions left to test after this (roughly 0 steps)
> [52b03dd70261934688cb00768c4b1e404716a337] qemu-kvm: Move
> kvm_set_boot_cpu_id
> 
> 
> $ git show
> commit 7811d4e8ec057d25db68f900be1f09a142faca49
> Author: Marcelo Tosatti <mtosatti@redhat.com>
> Date:   Mon Mar 1 21:36:31 2010 -0300
> 
> 
> If I manually back out the patch it will boot fine.
> 

Problem persists after removing the build directory and doing a fresh
configure && make? I'm asking before taking the bug (which would be
mine, likely) as I recently spent some hours "debugging" a volatile
build system issue.

Jan


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Re: segfault at start with latest qemu-kvm.git

[David S. Ahern]

On 03/03/2010 04:08 PM, Jan Kiszka wrote:
> David S. Ahern wrote:
>> With latest qemu-kvm.git I am getting a segfault at start:
>>
>> /tmp/qemu-kvm-test/bin/qemu-system-x86_64 -m 1024 -smp 2 \
>>   -drive file=/images/f12-x86_64.img,if=virtio,cache=none,boot=on
>>
>> kvm_create_vcpu: Invalid argument
>> Segmentation fault (core dumped)
>>
>>
>> git bisect points to:
>>
>> Bisecting: 0 revisions left to test after this (roughly 0 steps)
>> [52b03dd70261934688cb00768c4b1e404716a337] qemu-kvm: Move
>> kvm_set_boot_cpu_id
>>
>>
>> $ git show
>> commit 7811d4e8ec057d25db68f900be1f09a142faca49
>> Author: Marcelo Tosatti <mtosatti@redhat.com>
>> Date:   Mon Mar 1 21:36:31 2010 -0300
>>
>>
>> If I manually back out the patch it will boot fine.
>>
> 
> Problem persists after removing the build directory and doing a fresh
> configure && make? I'm asking before taking the bug (which would be
> mine, likely) as I recently spent some hours "debugging" a volatile
> build system issue.
> 
> Jan
> 

Before sending the email I pulled a fresh clone in a completely
different directory (/tmp) to determine if it was something I
introduced. I then went back to my usual location, unapplied the patch
and it worked fine.

David

Re: segfault at start with latest qemu-kvm.git

[Jan Kiszka]

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David S. Ahern wrote:
> 
> 
> 
> On 03/03/2010 04:08 PM, Jan Kiszka wrote:
>> David S. Ahern wrote:
>>> With latest qemu-kvm.git I am getting a segfault at start:
>>>
>>> /tmp/qemu-kvm-test/bin/qemu-system-x86_64 -m 1024 -smp 2 \
>>>   -drive file=/images/f12-x86_64.img,if=virtio,cache=none,boot=on
>>>
>>> kvm_create_vcpu: Invalid argument
>>> Segmentation fault (core dumped)
>>>
>>>
>>> git bisect points to:
>>>
>>> Bisecting: 0 revisions left to test after this (roughly 0 steps)
>>> [52b03dd70261934688cb00768c4b1e404716a337] qemu-kvm: Move
>>> kvm_set_boot_cpu_id
>>>
>>>
>>> $ git show
>>> commit 7811d4e8ec057d25db68f900be1f09a142faca49
>>> Author: Marcelo Tosatti <mtosatti@redhat.com>
>>> Date:   Mon Mar 1 21:36:31 2010 -0300
>>>
>>>
>>> If I manually back out the patch it will boot fine.
>>>
>> Problem persists after removing the build directory and doing a fresh
>> configure && make? I'm asking before taking the bug (which would be
>> mine, likely) as I recently spent some hours "debugging" a volatile
>> build system issue.
>>
>> Jan
>>
> 
> Before sending the email I pulled a fresh clone in a completely
> different directory (/tmp) to determine if it was something I
> introduced. I then went back to my usual location, unapplied the patch
> and it worked fine.

OK, that reason can be excluded. What's your host kernel kvm version?

(Of course, the issue does not show up here. But virtio currently does
not boot for me - independent of my patch.)

Jan


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Re: segfault at start with latest qemu-kvm.git

[David S. Ahern]

On 03/03/2010 04:20 PM, Jan Kiszka wrote:
> David S. Ahern wrote:
>>
>>
>>
>> On 03/03/2010 04:08 PM, Jan Kiszka wrote:
>>> David S. Ahern wrote:
>>>> With latest qemu-kvm.git I am getting a segfault at start:
>>>>
>>>> /tmp/qemu-kvm-test/bin/qemu-system-x86_64 -m 1024 -smp 2 \
>>>>   -drive file=/images/f12-x86_64.img,if=virtio,cache=none,boot=on
>>>>
>>>> kvm_create_vcpu: Invalid argument
>>>> Segmentation fault (core dumped)
>>>>
>>>>
>>>> git bisect points to:
>>>>
>>>> Bisecting: 0 revisions left to test after this (roughly 0 steps)
>>>> [52b03dd70261934688cb00768c4b1e404716a337] qemu-kvm: Move
>>>> kvm_set_boot_cpu_id
>>>>
>>>>
>>>> $ git show
>>>> commit 7811d4e8ec057d25db68f900be1f09a142faca49
>>>> Author: Marcelo Tosatti <mtosatti@redhat.com>
>>>> Date:   Mon Mar 1 21:36:31 2010 -0300
>>>>
>>>>
>>>> If I manually back out the patch it will boot fine.
>>>>
>>> Problem persists after removing the build directory and doing a fresh
>>> configure && make? I'm asking before taking the bug (which would be
>>> mine, likely) as I recently spent some hours "debugging" a volatile
>>> build system issue.
>>>
>>> Jan
>>>
>>
>> Before sending the email I pulled a fresh clone in a completely
>> different directory (/tmp) to determine if it was something I
>> introduced. I then went back to my usual location, unapplied the patch
>> and it worked fine.
> 
> OK, that reason can be excluded. What's your host kernel kvm version?
> 
> (Of course, the issue does not show up here. But virtio currently does
> not boot for me - independent of my patch.)
> 
> Jan
> 

Fedora Core 12,

Linux daahern-lx 2.6.31.12-174.2.22.fc12.x86_64 #1 SMP Fri Feb 19
18:55:03 UTC 2010 x86_64 x86_64 x86_64 GNU/Linux

David

Re: segfault at start with latest qemu-kvm.git

[Jan Kiszka]

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David S. Ahern wrote:
> On 03/03/2010 04:20 PM, Jan Kiszka wrote:
>> David S. Ahern wrote:
>>>
>>>
>>> On 03/03/2010 04:08 PM, Jan Kiszka wrote:
>>>> David S. Ahern wrote:
>>>>> With latest qemu-kvm.git I am getting a segfault at start:
>>>>>
>>>>> /tmp/qemu-kvm-test/bin/qemu-system-x86_64 -m 1024 -smp 2 \
>>>>>   -drive file=/images/f12-x86_64.img,if=virtio,cache=none,boot=on
>>>>>
>>>>> kvm_create_vcpu: Invalid argument
>>>>> Segmentation fault (core dumped)
>>>>>
>>>>>
>>>>> git bisect points to:
>>>>>
>>>>> Bisecting: 0 revisions left to test after this (roughly 0 steps)
>>>>> [52b03dd70261934688cb00768c4b1e404716a337] qemu-kvm: Move
>>>>> kvm_set_boot_cpu_id
>>>>>
>>>>>
>>>>> $ git show
>>>>> commit 7811d4e8ec057d25db68f900be1f09a142faca49
>>>>> Author: Marcelo Tosatti <mtosatti@redhat.com>
>>>>> Date:   Mon Mar 1 21:36:31 2010 -0300
>>>>>
>>>>>
>>>>> If I manually back out the patch it will boot fine.
>>>>>
>>>> Problem persists after removing the build directory and doing a fresh
>>>> configure && make? I'm asking before taking the bug (which would be
>>>> mine, likely) as I recently spent some hours "debugging" a volatile
>>>> build system issue.
>>>>
>>>> Jan
>>>>
>>> Before sending the email I pulled a fresh clone in a completely
>>> different directory (/tmp) to determine if it was something I
>>> introduced. I then went back to my usual location, unapplied the patch
>>> and it worked fine.
>> OK, that reason can be excluded. What's your host kernel kvm version?
>>
>> (Of course, the issue does not show up here. But virtio currently does
>> not boot for me - independent of my patch.)
>>
>> Jan
>>
> 
> Fedora Core 12,
> 
> Linux daahern-lx 2.6.31.12-174.2.22.fc12.x86_64 #1 SMP Fri Feb 19
> 18:55:03 UTC 2010 x86_64 x86_64 x86_64 GNU/Linux
> 

Reproduced after switching back to kvm-kmod-2.6.31, will debug.

Thanks,
Jan


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Re: segfault at start with latest qemu-kvm.git

[Jan Kiszka]

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Jan Kiszka wrote:
> David S. Ahern wrote:
>> On 03/03/2010 04:20 PM, Jan Kiszka wrote:
>>> David S. Ahern wrote:
>>>>
>>>> On 03/03/2010 04:08 PM, Jan Kiszka wrote:
>>>>> David S. Ahern wrote:
>>>>>> With latest qemu-kvm.git I am getting a segfault at start:
>>>>>>
>>>>>> /tmp/qemu-kvm-test/bin/qemu-system-x86_64 -m 1024 -smp 2 \
>>>>>>   -drive file=/images/f12-x86_64.img,if=virtio,cache=none,boot=on
>>>>>>
>>>>>> kvm_create_vcpu: Invalid argument
>>>>>> Segmentation fault (core dumped)
>>>>>>
>>>>>>
>>>>>> git bisect points to:
>>>>>>
>>>>>> Bisecting: 0 revisions left to test after this (roughly 0 steps)
>>>>>> [52b03dd70261934688cb00768c4b1e404716a337] qemu-kvm: Move
>>>>>> kvm_set_boot_cpu_id
>>>>>>
>>>>>>
>>>>>> $ git show
>>>>>> commit 7811d4e8ec057d25db68f900be1f09a142faca49
>>>>>> Author: Marcelo Tosatti <mtosatti@redhat.com>
>>>>>> Date:   Mon Mar 1 21:36:31 2010 -0300
>>>>>>
>>>>>>
>>>>>> If I manually back out the patch it will boot fine.
>>>>>>
>>>>> Problem persists after removing the build directory and doing a fresh
>>>>> configure && make? I'm asking before taking the bug (which would be
>>>>> mine, likely) as I recently spent some hours "debugging" a volatile
>>>>> build system issue.
>>>>>
>>>>> Jan
>>>>>
>>>> Before sending the email I pulled a fresh clone in a completely
>>>> different directory (/tmp) to determine if it was something I
>>>> introduced. I then went back to my usual location, unapplied the patch
>>>> and it worked fine.
>>> OK, that reason can be excluded. What's your host kernel kvm version?
>>>
>>> (Of course, the issue does not show up here. But virtio currently does
>>> not boot for me - independent of my patch.)
>>>
>>> Jan
>>>
>> Fedora Core 12,
>>
>> Linux daahern-lx 2.6.31.12-174.2.22.fc12.x86_64 #1 SMP Fri Feb 19
>> 18:55:03 UTC 2010 x86_64 x86_64 x86_64 GNU/Linux
>>
> 
> Reproduced after switching back to kvm-kmod-2.6.31, will debug.
> 

Subtle memory corruption: qemu_malloc is returning a pointer that
happens to become kvm_state twice. I bet my patch just exchanges some of
the involved parties and exposes the issue more prominently. Trying to
understand malloc's issue now...

Jan


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