qrexec_agent/gui_agent dies when getting "unchaced-minus" pages

[marmarek]

Reported by joanna on 8 Oct 2012 11:13 UTC
After upgrading to 3.2.30 (both in Dom0 and VMs) I started getting the following crashes in the VMs:

[   11.062632] qrexec_agent:388 map pfn expected mapping type write-back for 53000-54000, got uncached-minus
[   11.062970] qrexec_agent:388 freeing invalid memtype 53000-54000

... and similar for gui_agent, although don't have a log at hand to paste it here.

As a result, the qrexec or gui agent silently dies in the VM (e.g. there is no "yellow triangle" in the manager displayed), and it is no longer possible to execute any apps from the VM.

Migrated-From: https://wiki.qubes-os.org/ticket/663

[marmarek]

Comment by joanna on 5 Dec 2012 12:06 UTC
Interestingly, I've never seen this again. Closing for now.

[marmarek]

Comment by joanna on 5 Dec 2012 12:06 UTC
Interestingly, I've never seen this again. Closing for now.

[marmarek]

Comment by marmarek on 5 Dec 2012 12:58 UTC
I've seen this once or twice, but it is rather rare bug. Perhaps this is related to this workaround [which is included in 3.4.x (so 3.2 is still buggy). Unfortunately this workaround makes terrible performance of GPU driver. Kernel in my devel-3.4 branch have this workaround reverted and applied proper fix (which isn't included in upstream kernel and will not be - details here 2)

[http://git.kernel.org/?p=linux/kernel/git/konrad/xen.git;a=commit;h=8eaffa67b43e99ae581622c5133e20b0f48bcef1
2 https://lkml.org/lkml/2012/2/10/228

[marmarek]

Comment by marmarek on 5 Dec 2012 12:58 UTC
I've seen this once or twice, but it is rather rare bug. Perhaps this is related to this workaround [which is included in 3.4.x (so 3.2 is still buggy). Unfortunately this workaround makes terrible performance of GPU driver. Kernel in my devel-3.4 branch have this workaround reverted and applied proper fix (which isn't included in upstream kernel and will not be - details here 2)

[http://git.kernel.org/?p=linux/kernel/git/konrad/xen.git;a=commit;h=8eaffa67b43e99ae581622c5133e20b0f48bcef1
2 https://lkml.org/lkml/2012/2/10/228