[Xen-devel] RE: [PATCH] mem_sharing: fix race condition of nominate and unshare

[MaoXiaoyun <tinnycloud@xxxxxxxxxxx>]

Hi Tim:
 
        That's it, I am running the test, so far so good, I'll test more, thanks.
 
      Currently from the code of tapdisk, it indicates only *read only* IO with secs 8 has the
chance to be shared, so does it mean only the parent image can be shared, still it needs to
be opened read only, right?
 
      So it looks like page sharing are refer to those pages contain disk data been loaded
into Guest IO buffer, and this is the page sharing in Xen, right?     
             
 
> Date: Wed, 12 Jan 2011 14:02:23 +0000
> From: Tim.Deegan@xxxxxxxxxx
> To: tinnycloud@xxxxxxxxxxx
> CC: juihaochiang@xxxxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [PATCH] mem_sharing: fix race condition of nominate and unshare
>
> At 12:39 +0000 on 12 Jan (1294835994), MaoXiaoyun wrote:
> > Hi Tim:
> >
> > Seems not work. See log below.
> > Since the patch is for xen_unstable, I need to merge the code manually, I will check my code carefully later.
> >
>
> I think you need this change as well:
>
> diff -r d8eef6e395a8 xen/arch/x86/mm.c
> --- a/xen/arch/x86/mm.c Wed Jan 12 10:51:38 2011 +0000
> +++ b/xen/arch/x86/mm.c Wed Jan 12 14:01:11 2011 +0000
> @@ -2367,7 +2367,7 @@ static int __get_page_type(struct page_i
>
> /* No special validation needed for writable pages. */
> /* Page tables and GDT/LDT need to be scanned f or validity. */
> - if ( type == PGT_writable_page )
> + if ( type == PGT_writable_page || type == PGT_shared_page )
> nx |= PGT_validated;
> }
> }
>
>
> Cheers,
>
> Tim.
>
> --
> Tim Deegan <Tim.Deegan@xxxxxxxxxx>
> Principal Software Engineer, Xen Platform Team
> Citrix Systems UK Ltd. (Company #02937203, SL9 0BG)

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