Re: [Xen-devel] Live migration fails under heavy network use

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 21/2/07 00:41, "John Levon" <levon@xxxxxxxxxxxxxxxxx> wrote:

> On Wed, Feb 21, 2007 at 12:06:52AM +0000, Keir Fraser wrote:
> 
>>> Urk. Checkout line 204 of privcmd.c
>>> That doesn't look too 64b clean to me....
> 
> Hmm, I never looked at the Linux privcmd driver before. It seems like
> you're prefaulting all the pages in the ioctl() in on the ioctl.
> Currently on Solaris we're demand-faulting each page in the mmap() ...
> 
> It looks like we're not checking that we ca actually map the page at the
> time of the ioctl(), thus it's not ending up as marked with that bit.
> 
> Looks like our bug...

If you check then you may as well map at the same time. I think it would
actually be hard to defer the mapping in a race-free manner.

 -- Keir



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