ACK: [SRU][F][G][H][PATCH 1/1] s390/vtime: fix increased steal time accounting

[Tim Gardner]

Acked-by: Tim Gardner <tim.gardner at canonical.com>

On 3/29/21 10:15 AM, frank.heimes at canonical.com wrote:
> From: Gerald Schaefer <gerald.schaefer at linux.ibm.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1921498
> 
> Commit 152e9b8676c6e ("s390/vtime: steal time exponential moving average")
> inadvertently changed the input value for account_steal_time() from
> "cputime_to_nsecs(steal)" to just "steal", resulting in broken increased
> steal time accounting.
> 
> Fix this by changing it back to "cputime_to_nsecs(steal)".
> 
> Fixes: 152e9b8676c6e ("s390/vtime: steal time exponential moving average")
> Cc: <stable at vger.kernel.org> # 5.1
> Reported-by: Sabine Forkel <sabine.forkel at de.ibm.com>
> Reviewed-by: Heiko Carstens <hca at linux.ibm.com>
> Signed-off-by: Gerald Schaefer <gerald.schaefer at linux.ibm.com>
> Signed-off-by: Heiko Carstens <hca at linux.ibm.com>
> (cherry picked from commit d54cb7d54877d529bc1e0e1f47a3dd082f73add3)
> Signed-off-by: Frank Heimes <frank.heimes at canonical.com>
> ---
>   arch/s390/kernel/vtime.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
> index 3e72f955bff7..6e60cc2443b2 100644
> --- a/arch/s390/kernel/vtime.c
> +++ b/arch/s390/kernel/vtime.c
> @@ -217,7 +217,7 @@ void vtime_flush(struct task_struct *tsk)
>   	avg_steal = S390_lowcore.avg_steal_timer / 2;
>   	if ((s64) steal > 0) {
>   		S390_lowcore.steal_timer = 0;
> -		account_steal_time(steal);
> +		account_steal_time(cputime_to_nsecs(steal));
>   		avg_steal += steal;
>   	}
>   	S390_lowcore.avg_steal_timer = avg_steal;
> 

-- 
-----------
Tim Gardner
Canonical, Inc