From: David Vrabel <dvrabel@cantab.net>
To: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: xen-devel@lists.xensource.com, ian.campbell@citrix.com,
linux-kernel@vger.kernel.org, alex@alex.org.uk,
dcrisan@flexiant.com
Subject: Re: [Xen-devel] [PATCH v3 1/2] xen/balloon: set a mapping for ballooned out pages
Date: Wed, 24 Jul 2013 18:37:35 +0100 [thread overview]
Message-ID: <51F010DF.60204@cantab.net> (raw)
In-Reply-To: <1374600466-3229-1-git-send-email-stefano.stabellini@eu.citrix.com>
On 23/07/13 18:27, Stefano Stabellini wrote:
> Currently ballooned out pages are mapped to 0 and have INVALID_P2M_ENTRY
> in the p2m. These ballooned out pages are used to map foreign grants
> by gntdev and blkback (see alloc_xenballooned_pages).
>
> Allocate a page per cpu and map all the ballooned out pages to the
> corresponding mfn. Set the p2m accordingly. This way reading from a
> ballooned out page won't cause a kernel crash (see
> http://lists.xen.org/archives/html/xen-devel/2012-12/msg01154.html).
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
A number of users of DEFINE_PER_CPU() initialize it with
for_each_possible_cpu() without registering a cpu notifier, so I think
there is no risk that offlining a CPU clears its per-cpu data and the
code as-is is fine.
David
next prev parent reply other threads:[~2013-07-24 17:37 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-23 17:26 [PATCH v3 0/2] make ballooned out pages have a valid mapping at all times Stefano Stabellini
2013-07-23 17:27 ` [PATCH v3 1/2] xen/balloon: set a mapping for ballooned out pages Stefano Stabellini
2013-07-23 17:27 ` Stefano Stabellini
2013-07-23 18:00 ` Ian Campbell
2013-07-23 18:00 ` Ian Campbell
2013-07-23 19:05 ` Konrad Rzeszutek Wilk
2013-07-24 11:05 ` Stefano Stabellini
2013-07-24 11:05 ` Stefano Stabellini
2013-07-24 14:58 ` Konrad Rzeszutek Wilk
2013-07-25 3:31 ` Ian Campbell
2013-07-25 3:31 ` Ian Campbell
2013-07-29 14:10 ` Konrad Rzeszutek Wilk
2013-08-04 14:30 ` Stefano Stabellini
2013-08-04 14:30 ` Stefano Stabellini
2013-07-24 17:37 ` David Vrabel [this message]
2013-07-23 17:27 ` [PATCH v3 2/2] xen/m2p: use GNTTABOP_unmap_and_replace to reinstate the original mapping Stefano Stabellini
2013-07-23 17:27 ` Stefano Stabellini
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