e easily, as blkfront will allocate new grants with a
> > > much higher frequency.
> > >
> > > So fixing the persistent grant issue will just paper over the real
> > > issue.
> >
> > Indeed so, but making the bug happen much less frequently is still a
&g
t; > > > > > rays or other random bit-flips.
> > > > > > >
> > > > > > > Marek, do you have any suggestions?
> > > > > >
> > > > > > To me that sounds like the interface of the GUI is the culprit.
> > > >
15.61. The latter reports persistent grants disabled.
I think this additional bug is just triggering the race in the GUI
interface more easily, as blkfront will allocate new grants with a
1. Treat “backend has not unmapped grant” errors as non-fatal. The most
likely cause is buggy user
> > > > >
> > > > > To me that sounds like the interface of the GUI is the culprit.
> > > > >
> > > > > The GUI agent in the guest should only free a grant, if it got a
> > > > > message
> > > > > from the b
lities and communication regarding
grants is important here.
To fix this problem, I recommend the following changes:
1. Treat “backend has not unmapped grant” errors as non-fatal. The most
likely cause is buggy userspace software, not an attempt to exploit
XSA-396. Instead of disabling the de
al
> issue.
Indeed so, but making the bug happen much less frequently is still a
significant win for users.
In the long term, there is one situation I do not have a good solution
for: recovery from GUI agent crashes. If the GUI agent crashes, the
kernel it is running under has two bad choices. Eithe
Hi Juergen,
Thank you for the quick and nice reply!
On Thu, 25 Aug 2022 08:20:33 +0200 Juergen Gross wrote:
>
[...]
>
> Could you please send it as two proper patches (one for each driver) with
> the correct "Fixes:" tags?
Sure, just posted:
https://lore.kernel.org/xen-devel/20220825161511.
On 24.08.22 22:38, SeongJae Park wrote:
+ Roger
On Wed, 24 Aug 2022 17:44:42 + SeongJae Park wrote:
Hello,
On Wed, 24 Aug 2022 08:02:40 +0200 Juergen Gross wrote:
[-- Attachment #1.1.1: Type: text/plain, Size: 4312 bytes --]
On 24.08.22 02:20, Marek Marczykowski-Górecki wrote:
FWIW
+ Roger
On Wed, 24 Aug 2022 17:44:42 + SeongJae Park wrote:
> Hello,
>
> On Wed, 24 Aug 2022 08:02:40 +0200 Juergen Gross wrote:
>
> >
> > [-- Attachment #1.1.1: Type: text/plain, Size: 4312 bytes --]
> >
> > On 24.08.22 02:20, Marek Marczykowski-Górecki wrote:
> > > FWIW, I hit this is
Hello,
On Wed, 24 Aug 2022 08:02:40 +0200 Juergen Gross wrote:
>
> [-- Attachment #1.1.1: Type: text/plain, Size: 4312 bytes --]
>
> On 24.08.22 02:20, Marek Marczykowski-Górecki wrote:
> > FWIW, I hit this issue twice already in this week CI run, while it never
> > happened before. The differ
On 24.08.2022 08:36, Juergen Gross wrote:
> On 24.08.22 08:30, Jan Beulich wrote:
>> On 24.08.2022 08:02, Juergen Gross wrote:
>>> The blkif.h comments should be updated to make it clear that the values in
>>> Xenstore don't reflect the state of the connection, but the availability of
>>> the featu
On 24.08.22 08:30, Jan Beulich wrote:
On 24.08.2022 08:02, Juergen Gross wrote:
The blkif.h comments should be updated to make it clear that the values in
Xenstore don't reflect the state of the connection, but the availability of
the feature in the related driver.
Isn't that implied for all t
On 24.08.2022 08:02, Juergen Gross wrote:
> The blkif.h comments should be updated to make it clear that the values in
> Xenstore don't reflect the state of the connection, but the availability of
> the feature in the related driver.
Isn't that implied for all the feature-* leaves? I certainly don
On 24.08.22 02:20, Marek Marczykowski-Górecki wrote:
On Tue, Aug 23, 2022 at 09:48:57AM +0200, Juergen Gross wrote:
On 23.08.22 09:40, Demi Marie Obenour wrote:
I recently had a VM’s /dev/xvdb stop working with a “backend has not
unmapped grant” error. Since /dev/xvdb was the VM’s private volu
On 24.08.22 02:20, Marek Marczykowski-Górecki wrote:
FWIW, I hit this issue twice already in this week CI run, while it never
happened before. The difference compared to previous run is Linux
5.15.57 vs 5.15.61. The latter reports persistent grants disabled. The
only related commits I see there a
On Tue, Aug 23, 2022 at 09:48:57AM +0200, Juergen Gross wrote:
> On 23.08.22 09:40, Demi Marie Obenour wrote:
> > I recently had a VM’s /dev/xvdb stop working with a “backend has not
> > unmapped grant” error. Since /dev/xvdb was the VM’s private volume,
> > that rendered the VM effectively useles
On 23.08.22 09:40, Demi Marie Obenour wrote:
I recently had a VM’s /dev/xvdb stop working with a “backend has not
unmapped grant” error. Since /dev/xvdb was the VM’s private volume,
that rendered the VM effectively useless. I had to kill it with
qvm-kill.
The backend of /dev/xvdb is dom0, so a
I recently had a VM’s /dev/xvdb stop working with a “backend has not
unmapped grant” error. Since /dev/xvdb was the VM’s private volume,
that rendered the VM effectively useless. I had to kill it with
qvm-kill.
The backend of /dev/xvdb is dom0, so a malicious backend is clearly not
the cause of
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