xen: execve's error paths don't pin the mm before unpinning
execve's error paths don't activate (and therefore pin) the mm before
calling exit_mmap to free it up, so don't try to unpin unless it is
actually pinned. This prevents a BUG_ON from triggering.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Christian Ostheimer <osth@freesurf.ch>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/i386/xen/mmu.c b/arch/i386/xen/mmu.c
index 4ae038a..874db0c 100644
--- a/arch/i386/xen/mmu.c
+++ b/arch/i386/xen/mmu.c
@@ -559,6 +559,9 @@
put_cpu();
spin_lock(&mm->page_table_lock);
- xen_pgd_unpin(mm->pgd);
+
+ /* pgd may not be pinned in the error exit path of execve */
+ if (PagePinned(virt_to_page(mm->pgd)))
+ xen_pgd_unpin(mm->pgd);
spin_unlock(&mm->page_table_lock);
}