Commit b6497b38 authored Dec 06, 2013 by Ian Campbell Committed by Stefano Stabellini Dec 06, 2013

xen: privcmd: do not return pages which we have failed to unmap



This failure represents a hypervisor issue, but if it does occur then nothing
good can come of returning pages which still refer to a foreign owned page
into the general allocation pool.

Instead we are forced to leak them. Log that we have done so.

The potential for failure only exists for autotranslated guest (e.g. ARM and
x86 PVH).

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>

parent c94cae53

drivers/xen/privcmd.c

+7 −2

Original line number	Diff line number	Diff line
		@@ -533,12 +533,17 @@ static void privcmd_close(struct vm_area_struct *vma)
		{
		struct page **pages = vma->vm_private_data;
		int numpgs = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
		int rc;

		if (!xen_feature(XENFEAT_auto_translated_physmap) \|\| !numpgs \|\| !pages)
		return;

		xen_unmap_domain_mfn_range(vma, numpgs, pages);
		rc = xen_unmap_domain_mfn_range(vma, numpgs, pages);
		if (rc == 0)
		free_xenballooned_pages(numpgs, pages);
		else
		pr_crit("unable to unmap MFN range: leaking %d pages. rc=%d\n",
		numpgs, rc);
		kfree(pages);
		}

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