From b6497b383f65dd1bc60ea1f5d70e157a268fbd15 Mon Sep 17 00:00:00 2001
From: Ian Campbell <Ian.Campbell@citrix.com>
Date: Fri, 6 Dec 2013 17:55:56 +0000
Subject: 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>

diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index 8e74590..569a13b 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -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);
-	free_xenballooned_pages(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);
 }
 
-- 
cgit v0.10.2