From: Juergen Gross <jgross@suse.com>
To: David Hildenbrand <david@redhat.com>, xen-devel@lists.xenproject.org
Cc: linux-kernel@vger.kernel.org,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Julien Grall <julien.grall@arm.com>,
Matthew Wilcox <willy@infradead.org>,
Nadav Amit <namit@vmware.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
akpm@linux-foundation.org, linux-mm@kvack.org,
Oscar Salvador <osalvador@suse.de>,
Jan Beulich <JBeulich@suse.com>
Subject: Re: [PATCH v2] xen/balloon: Fix mapping PG_offline pages to user space
Date: Thu, 14 Mar 2019 17:05:33 +0100 [thread overview]
Message-ID: <d02a354b-6b40-6fd9-b09b-debfee7d2071@suse.com> (raw)
In-Reply-To: <20190314160256.21713-1-david@redhat.com>
On 14/03/2019 17:02, David Hildenbrand wrote:
> The XEN balloon driver - in contrast to other balloon drivers - allows
> to map some inflated pages to user space. Such pages are allocated via
> alloc_xenballooned_pages() and freed via free_xenballooned_pages().
> The pfn space of these allocated pages is used to map other things
> by the hypervisor using hypercalls.
>
> Pages marked with PG_offline must never be mapped to user space (as
> this page type uses the mapcount field of struct pages).
>
> So what we can do is, clear/set PG_offline when allocating/freeing an
> inflated pages. This way, most inflated pages can be excluded by
> dumping tools and the "reused for other purpose" balloon pages are
> correctly not marked as PG_offline.
>
> Fixes: 77c4adf6a6df (xen/balloon: mark inflated pages PG_offline)
> Reported-by: Julien Grall <julien.grall@arm.com>
> Tested-by: Julien Grall <julien.grall@arm.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Juergen
next prev parent reply other threads:[~2019-03-14 16:05 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-14 16:02 David Hildenbrand
2019-03-14 16:05 ` Juergen Gross [this message]
2019-03-15 14:53 ` Juergen Gross
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