Re: Hypervisor error messages after xl block-detach with linux 3.18-rc5

[Juergen Gross <jgross@suse.com>]

On 11/21/2014 02:57 PM, Konrad Rzeszutek Wilk wrote:
> On Fri, Nov 21, 2014 at 09:42:11AM +0100, Juergen Gross wrote:
>> Hi,
>>
>> while testing my "linear p2m list" patches I saw the following
>> problem (even without my patches in place):
>>
>> In dom0 running linux 3.18-rc5 on top of Xen 4.4.1 I modified the
>> disk image of a guest by attaching it to dom0:
>>
>> xl block-attach 0 file:/var/lib/libvirt/images/opensuse13-1/xvda,xvda,w
>> mount /dev/xvda2 /mnt
>> ...
>> umount /mnt
>> xl block-detach 0 xvda

Did some more testing:
- Seems to occur only when attaching a block device to dom0, problem
   shows up only after doing the block-detach.
- Sometimes I see only NMI watchdog messages, looking into hanging cpu
   state via xen debug keys I can see the cpu(s) in question are spinning
   in _raw_spin_lock():
   __handle_mm_fault()->__pte_alloc()->pmd_lock()->_raw_spin_lock()
   The hanging cpus were executing some random user processes (cron,
   bash, xargs), cr2 contained user addresses.
- Up to now I've seen the problem on a rather huge machine only (128GB,
   120 cpus). I just did a quick test on my laptop and nothing bad
   happened.
- Even on the huge machine just doing block-attach and block-detach
   without mounting the filesystem on the disk was harmless.

Any ideas how to find the problem?


Juergen

>>
>> Worked without any problem. After some seconds the following messages
>> were issued on the console:
>>
>> (XEN) mm.c:2352:d0 Bad type (saw 7400000000000002 != exp 1000000000000000)
>> for mfn 61110 (pfn 1f3f21c)
>> (XEN) mm.c:2995:d0 Error while pinning mfn 61110
>> (XEN) mm.c:2352:d0 Bad type (saw 7400000000000002 != exp 1000000000000000)
>> for mfn 61110 (pfn 1f3f21c)
>> (XEN) mm.c:906:d0 Attempt to create linear p.t. with write perms
>> (XEN) mm.c:2352:d0 Bad type (saw 7400000000000002 != exp 1000000000000000)
>> for mfn 61111 (pfn 1f3f21d)
>> (XEN) mm.c:2995:d0 Error while pinning mfn 61111
>> (XEN) mm.c:2352:d0 Bad type (saw 7400000000000002 != exp 1000000000000000)
>> for mfn 61111 (pfn 1f3f21d)
>> (XEN) mm.c:906:d0 Attempt to create linear p.t. with write perms
>> (XEN) mm.c:2352:d0 Bad type (saw 7400000000000002 != exp 1000000000000000)
>> for mfn 61120 (pfn 1f3f22c)
>> (XEN) mm.c:2995:d0 Error while pinning mfn 61120
>> (XEN) mm.c:2352:d0 Bad type (saw 7400000000000002 != exp 1000000000000000)
>> for mfn 61120 (pfn 1f3f22c)
>> (XEN) mm.c:906:d0 Attempt to create linear p.t. with write perms
>> (XEN) mm.c:2352:d0 Bad type (saw 7400000000000002 != exp 1000000000000000)
>> for mfn 61121 (pfn 1f3f22d)
>> (XEN) mm.c:2995:d0 Error while pinning mfn 61121
>> (XEN) mm.c:2352:d0 Bad type (saw 7400000000000002 != exp 1000000000000000)
>> for mfn 61121 (pfn 1f3f22d)
>> (XEN) mm.c:906:d0 Attempt to create linear p.t. with write perms
>> (XEN) mm.c:2352:d0 Bad type (saw 7400000000000002 != exp 1000000000000000)
>> for mfn 61102 (pfn 1f3f20e)
>> (XEN) mm.c:2995:d0 Error while pinning mfn 61102
>> (XEN) mm.c:2352:d0 Bad type (saw 7400000000000002 != exp 1000000000000000)
>> for mfn 61102 (pfn 1f3f20e)
>> (XEN) mm.c:906:d0 Attempt to create linear p.t. with write perms
>> (XEN) mm.c:2352:d0 Bad type (saw 7400000000000002 != exp 1000000000000000)
>> for mfn 61103 (pfn 1f3f20f)
>> (XEN) mm.c:2995:d0 Error while pinning mfn 61103
>> (XEN) mm.c:2352:d0 Bad type (saw 7400000000000002 != exp 1000000000000000)
>> for mfn 61103 (pfn 1f3f20f)
>> (XEN) mm.c:906:d0 Attempt to create linear p.t. with write perms
>>
>> Is this a known issue?
>
> No. First time I see it.
>>
>>
>> Juergen
>>
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>
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