Re: [Xen-devel] [PATCH for-4.8] altp2m: don't attempt to unshare pages during change_altp2m_gfn op

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On 14/10/16 01:00, Tamas K Lengyel wrote:
> Attempting to change gfn mappings with altp2m on a memory shared page results
> in a lock-order violation (mm locking order violation: 282 > 254), which
> crashes the hypervisor. Don't attempt to automatically unshare such pages and
> just fall back to failing the op if the page type is not correct.
> 
> Signed-off-by: Tamas K Lengyel <tamas.lengyel@xxxxxxxxxxxx>

It would be nice to try to untangle thus such that you can reasonably
unshare a page in this circumstance; but given the point in the release
cycle, making it return an error instead of crashing is probably the
right thing to do.

Reviewed-by: George Dunlap <george.dunlap@xxxxxxxxxx>

This needs a release ack now I think as well.



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