Re: port-xen/45975 (panic: HYPERVISOR_mmu_update failed, ret: -22 during heavy activity)

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Mon, Feb 13, 2012 at 04:25:02PM +0000, Jeff Rizzo wrote:
> The following reply was made to PR port-xen/45975; it has been noted by GNATS.
> 
> From: Jeff Rizzo <riz%netbsd.org@localhost>
> To: gnats-bugs%NetBSD.org@localhost
> Cc: 
> Subject: Re: port-xen/45975 (panic: HYPERVISOR_mmu_update failed, ret: -22
>  during heavy activity)
> Date: Mon, 13 Feb 2012 08:23:27 -0800
> 
>  On 2/13/12 1:49 AM, Manuel Bouyer wrote:
>  > please also send the last few lines of 'xm dmesg' if possible.
>  >
>  
>  Unfortunately, they're not timestamped, so it's hard for me to figure 
>  out what's relevant.  Here's the entire 'xm dmesg'.

You have the domain number ...

>  (XEN) mm.c:2424:d170 Bad type (saw 7400000000000001 != exp 
>  1000000000000000) for mfn 1e6705 (pfn 6edb)
>  (XEN) mm.c:915:d170 Attempt to create linear p.t. with write perms

All errors are of the same type, and looks similar to what you've
reported first. It means we're trying to use a page as a page table
which is already mapped read/write. So it's not the same problem
as the bug I corrected (I should have checked more carefully), where
Xen was telling me that a domU is trying to map read/write a page
already used as page table (so it's the opposite !).

Today I ran into the issue you're describing now. So the patch I
proposed is correct and fixes an issue; but it's not this one ...

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--