Re: [Xen-devel] doubt on releasing domain pages

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 21/8/08 22:28, "Sandesh" <sandesh.ahiremath@xxxxxxxxx> wrote:

>   I am trying to release domU pages from page_list and xenpage_list
> after domU shutdown while retaining the rest of the domain information.
> To achieve this in __domain_finalise_shutdown i call
> domain_relinquish_resources. This is failing to release pages from
> page_list for type PGT_l2_page_tables and crashing dom0.
>   To be specific, while testing on mini-os i saw that when
> domain_relinquish_resources calls relinquish_memory for
> PGT_l2_page_tables, this eventually calls free_l2_table which fails at
> map_domain_page() by returning an invalid virtual address, due to which
> dom0 crashes immediately.
> 
> When the same sequence of functions works perfectly fine during domU
> destruction, why not during shutdown. Am I missing anything important?

I wouldn't guarantee that calling from shutdown will work entirely race-free
in all cases, but I would think it would generally work okay. A bad pointer
from map_domain_page() is odd -- make a debug build 'debug=y make' and
perhaps add tracing to see what's going wrong there.

 -- Keir



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