Re: [Xen-devel] [PATCH 6 of 8] x86/mm: Properly account for paged out pages

["Andres Lagar-Cavilla" <andres@xxxxxxxxxxxxxxxx>]

> On Thu, Jan 26, Andres Lagar-Cavilla wrote:
>
>> there is a put_page in case things go wrong, after the
>> alloc_domheap_page
>> call. So doing the decrement at alloc is a bit too soon.
>
> Thats probably true.
>
> But in the case of failure the guest will likely hang soon. Is the
> copy_from_user() (and p2m_mem_paging_prep itself) restartable? If not,
> the guest should probably be crashed.  The way xenpaging_populate_page()
> is written right now, it will just exit, EFAULT isnt caught.

p2m_mem_paging_prep is restartable, afaict. It cleanly undoes its deeds.

xenpaging not handling EFAULT ... that's a different issue/patch altogether.

Andres

>
> Olaf
>



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