Re: [Xen-devel] [PATCHv2 2/3] mm: don't free pages until mm locks are released

[David Vrabel <david.vrabel@xxxxxxxxxx>]

On 13/11/15 18:49, David Vrabel wrote:
> If a page is freed without translations being invalidated, and the page is
> subsequently allocated to another domain, a guest with a cached
> translation will still be able to access the page.
> 
> Currently translations are invalidated before releasing the page ref, but
> while still holding the mm locks.  To allow translations to be invalidated
> without holding the mm locks, we need to keep a reference to the page
> for a bit longer in some cases.
> 
> [ This seems difficult to a) verify as correct; and b) difficult to get
> correct in the future.  A better suggestion would be useful.  Perhaps
> using something like pg->tlbflush_needed mechanism that already exists
> for pages from PV guests? ]

ping?

This question is quite important and hasn't been answered yet.

David

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