[PATCH] xen: execve's error paths don't pin the mm before unpinning

From: Jeremy Fitzhardinge
Date: Tue Sep 25 2007 - 14:50:19 EST

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@xxxxxxxxxxxxx>
Cc: osth@xxxxxxxxxxx

arch/i386/xen/mmu.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/arch/i386/xen/mmu.c
+++ b/arch/i386/xen/mmu.c
@@ -558,6 +558,9 @@ void xen_exit_mmap(struct mm_struct *mm)

- 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);

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