ACK: [Trusty/Utopic SRU] Avoid xen balloon errors on AWS

[Brad Figg]

On 10/27/2014 05:56 AM, Stefan Bader wrote:
> Has not marked stable but is supposed to finally close the AWS reports
> about those messages flooding some instances dmesg.
> Limited to the Xen balloon driver, so there is not much chance this
> could cause problems outside. And outside AWS we could not get into
> those failures in the first place. But I am preparing test kernels for
> T as well.
> 
> -Stefan
> 
> 
> From fd8b79511349efd1f0decea920f61b93acb34a75 Mon Sep 17 00:00:00 2001
> From: Boris Ostrovsky <boris.ostrovsky at oracle.com>
> Date: Tue, 7 Oct 2014 17:00:07 -0400
> Subject: [PATCH] xen/balloon: Don't continue ballooning when BP_ECANCELED is
>  encountered
> 
> Commit 3dcf63677d4e ("xen/balloon: cancel ballooning if adding new
> memory failed") makes reserve_additional_memory() return BP_ECANCELED
> when an error is encountered. This error, however, is ignored by the
> caller (balloon_process()) since it is overwritten by subsequent call
> to update_schedule(). This results in continuous attempts to add more
> memory, all of which are likely to fail again.
> 
> We should stop trying to schedule next iteration of ballooning when
> the current one has failed.
> 
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky at oracle.com>
> Reviewed-by: Daniel Kiper <daniel.kiper at oracle.com>
> Signed-off-by: David Vrabel <david.vrabel at citrix.com>
> 
> BugLink: http://bugs.launchpad.net/bugs/1304001
> 
> (cherry-picked from commit fd8b79511349efd1f0decea920f61b93acb34a75 upstream)
> Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
> ---
>  drivers/xen/balloon.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
> index 1e0a317..3860d02 100644
> --- a/drivers/xen/balloon.c
> +++ b/drivers/xen/balloon.c
> @@ -167,6 +167,9 @@ static struct page *balloon_next_page(struct page *page)
>  
>  static enum bp_state update_schedule(enum bp_state state)
>  {
> +	if (state == BP_ECANCELED)
> +		return BP_ECANCELED;
> +
>  	if (state == BP_DONE) {
>  		balloon_stats.schedule_delay = 1;
>  		balloon_stats.retry_count = 1;
> 


-- 
Brad Figg brad.figg at canonical.com http://www.canonical.com