mmap() on pvops will not return FAILED if the memory can't be mapped or accessed.

mmap() on pvops will not return FAILED if the memory can't be mapped or accessed.

[Wang, Shane]

Jeremy,

I wrote an application calling mmap() on pvops and found it will not return FAILED if the mapped memory (say TXT heap) can't be mapped or accessed, unlike 2.6.18 domain 0 and the latest kernel.

The serial port outputs (XEN) mm.c:776:d0 Non-privileged (0) attempt to map I/O space 000af520...000af5ff, which is the same as the output of 2.6.18 dom0.
However, then it outputs many lines like (XEN) mm.c:838:d0 Error getting mfn ac247 (pfn a38aa) from L1 entry 80000000ac247425 for l1e_owner=0, pg_owner=32753....
This behaviour may cause dom0 hang finally.

Is it correct? Can you help to have a look at it?

Thanks.
Shane

Re: mmap() on pvops will not return FAILED if the memory can't be mapped or accessed.

[Jeremy Fitzhardinge]

On 01/07/2010 12:27 AM, Wang, Shane wrote:
> I wrote an application calling mmap() on pvops and found it will not return FAILED if the mapped memory (say TXT heap) can't be mapped or accessed, unlike 2.6.18 domain 0 and the latest kernel.
>
> The serial port outputs (XEN) mm.c:776:d0 Non-privileged (0) attempt to map I/O space 000af520...000af5ff, which is the same as the output of 2.6.18 dom0.
> However, then it outputs many lines like (XEN) mm.c:838:d0 Error getting mfn ac247 (pfn a38aa) from L1 entry 80000000ac247425 for l1e_owner=0, pg_owner=32753....
> This behaviour may cause dom0 hang finally.
>
> Is it correct? Can you help to have a look at it?
>    

Could you give more detail?  What architecture is the dom0 and Xen?  
What are the complete kernel and Xen console logs?  What is the program 
specifically trying to do?  Do you have a test program which can 
reproduce the problem?

     J