Re: [Xen-devel] arm: alloc_heap_pages allocates already allocated page

[Julien Grall <julien.grall@xxxxxxx>]

On 07/02/2017 08:18, Vijay Kilari wrote:
> Hi,
Hello,

>    I am seeing below panic with NUMA during DT mappings in alloc_heap_pages()
> BUG_ON(pg[i].count_info != PGC_state_free);
> However, this issue is not there with 4.7 version. The same NUMA board
> boots fine.
I am a bit confused by what you are saying. Xen on ARM does not yet 
support NUMA. I also know you are working on NUMA support. So does the 
BUG happen on upstream xen or upstream xen + your patches?
If the latter please provide more details on your modifications.

> With 4.8 or staging I see below panic.
I would recommend you to try bisecting to see if you can pin point a 
specific commit.
> I have add print in alloc_heap_pages to print page_to_mfn(pg) and
> before and after calling
> map_range_to_domain() DT mapping.
> It shows that 0x83e22a is returned for multiple alloc_heap_page requests.
This is fine as long as there is a free_heap_pages between the 2 calls 
of alloc_heap_pages. I would recommend you to look if free_heap_pages 
has been called.
[....]


> (XEN) Xen BUG at page_alloc.c:870
I was not able to spot a BUG at line 870 but 827. I think, the 
BUG_ON(PGC_state_free) is here to catch potential bug in the allocator, 
all the pages allocated should always be free.
Furthermore, we haven't made much changes in page_alloc.c recently. So 
this 43 lines differences made me wonder if you did other changes than 
adding debug?
Regards,

--
Julien Grall

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