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

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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>
This commit is contained in:
Ian Campbell 2013-12-06 17:55:56 +00:00 committed by Stefano Stabellini
parent c94cae53f9
commit b6497b383f
1 changed files with 7 additions and 2 deletions
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9
drivers/xen/privcmd.c
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@ -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);
}