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From: Jan Beulich <jbeulich@suse.com>
To: Juergen Gross <jgross@suse.com>
Cc: xen-devel@lists.xenproject.org,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [Xen-devel] [PATCH] xen/balloon: Support xend-based toolstack take two
Date: Fri, 17 Jan 2020 12:01:02 +0100	[thread overview]
Message-ID: <c29c92e3-eb20-7e0a-0174-ef72398b0998@suse.com> (raw)
In-Reply-To: <20200116170004.14373-1-jgross@suse.com>

On 16.01.2020 18:00, Juergen Gross wrote:
> Commit 3aa6c19d2f38be ("xen/balloon: Support xend-based toolstack")
> tried to fix a regression with running on rather ancient Xen versions.
> Unfortunately the fix was based on the assumption that xend would
> just use another Xenstore node, but in reality only some downstream
> versions of xend are doing that. The upstream xend does not write
> that Xenstore node at all, so the problem must be fixed in another
> way.
> 
> The easiest way to achieve that is to fall back to the behavior before
> commit 5266b8e4445c ("xen: fix booting ballooned down hvm guest")
> in case the static memory maximum can't be read.

I could use some help here: Prior to said commit there was

	target_diff = new_target - balloon_stats.target_pages;


Which is, afaict, ...

> --- a/drivers/xen/xen-balloon.c
> +++ b/drivers/xen/xen-balloon.c
> @@ -94,7 +94,7 @@ static void watch_target(struct xenbus_watch *watch,
>  				  "%llu", &static_max) == 1))
>  			static_max >>= PAGE_SHIFT - 10;
>  		else
> -			static_max = new_target;
> +			static_max = balloon_stats.current_pages;
>  
>  		target_diff = (xen_pv_domain() || xen_initial_domain()) ? 0
>  				: static_max - balloon_stats.target_pages;

... what the code does before your change. Afaict there was
never a use of balloon_stats.current_pages in this function.

Jan

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  parent reply	other threads:[~2020-01-17 11:01 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-16 17:00 [Xen-devel] [PATCH] xen/balloon: Support xend-based toolstack take two Juergen Gross
2020-01-16 19:32 ` Boris Ostrovsky
2020-01-17 11:01 ` Jan Beulich [this message]
2020-01-17 11:31   ` Jürgen Groß
2020-01-17 11:36     ` Jan Beulich
2020-01-17 11:45       ` Jürgen Groß

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