Re: [PATCH v3] xen: Fix x86 sched_clock() interface for xen

[Boris Ostrovsky]

On 1/14/19 7:44 AM, Juergen Gross wrote:
> Commit f94c8d11699759 ("sched/clock, x86/tsc: Rework the x86 'unstable'
> sched_clock() interface") broke Xen guest time handling across
> migration:
>
> [  187.249951] Freezing user space processes ... (elapsed 0.001 seconds) done.
> [  187.251137] OOM killer disabled.
> [  187.251137] Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done.
> [  187.252299] suspending xenstore...
> [  187.266987] xen:grant_table: Grant tables using version 1 layout
> [18446743811.706476] OOM killer enabled.
> [18446743811.706478] Restarting tasks ... done.
> [18446743811.720505] Setting capacity to 16777216
>
> Fix that by setting xen_sched_clock_offset at resume time to ensure a
> monotonic clock value.
>
> Fixes: f94c8d11699759 ("sched/clock, x86/tsc: Rework the x86 'unstable' sched_clock() interface")
> Cc: <stable@xxxxxxxxxxxxxxx> # 4.11
> Reported-by: Hans van Kranenburg <hans@xxxxxxxxxxx>
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>