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

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

The following reply was made to PR port-xen/45975; it has been noted by GNATS.

From: Manuel Bouyer <bouyer%antioche.eu.org@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: gnats-admin%NetBSD.org@localhost, netbsd-bugs%NetBSD.org@localhost, 
riz%NetBSD.org@localhost
Subject: Re: port-xen/45975 (panic: HYPERVISOR_mmu_update failed, ret: -22
 during heavy activity)
Date: Mon, 13 Feb 2012 17:37:38 +0100

 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
 --