Re: [Xen-devel] [PATCH] Input: xen-kbdfront - free grant table entry in xenkbd_disconnect_backend

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On Thu, Oct 16, 2014 at 05:01:09PM +0100, David Vrabel wrote:
> On 16/10/14 02:46, hansechang@gmail.com wrote:
> > From: Chang Huaixin <huaixin.chx@alibaba-inc.com>
> > 
> > xenkbd_disconnect_backend doesn't free grant table entry.
> > This bug affects live migration.
> > 
> > xenkbd_disconnect_backend uses gnttab_end_foreign_access_ref
> > to handle grant table entry which doesn't really free an entry.
> > 
> > Thus every time we do xenkbd_resume, grant table entry increses
> > by one. As an grant table entry occupies 8 bytes, an grant table
> > page has at most 512 entries. Every 512 times we do xenkdb_resume,
> > grant table pages increses by one.
> > 
> > After around 3500 times of live migration, grant table pages
> > will increase by 7, causing too many pages to populate and hitting
> > max_pages limit when assigning pages.Thus assign_pages will fail,
> > so will live migration.
> 
> Acked-by: David Vrabel <david.vrabel@citrix.com>
> 
> This need to be send to the input subsystem maintainers.

Applied, thank you.

-- 
Dmitry