Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/torvalds/linux-2.6

1 files changed, 17 insertions, 2 deletions

diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c
index d073b64ae87e..724ba3bce72c 100644
--- a/arch/arm/mm/alignment.c
+++ b/arch/arm/mm/alignment.c
@@ -885,8 +885,23 @@ do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 
         if (ai_usermode & UM_SIGNAL)
                 force_sig(SIGBUS, current);
-        else
-                set_cr(cr_no_alignment);
+        else {
+                /*
+                 * We're about to disable the alignment trap and return to
+                 * user space.  But if an interrupt occurs before actually
+                 * reaching user space, then the IRQ vector entry code will
+                 * notice that we were still in kernel space and therefore
+                 * the alignment trap won't be re-enabled in that case as it
+                 * is presumed to be always on from kernel space.
+                 * Let's prevent that race by disabling interrupts here (they
+                 * are disabled on the way back to user space anyway in
+                 * entry-common.S) and disable the alignment trap only if
+                 * there is no work pending for this thread.
+                 */
+                raw_local_irq_disable();
+                if (!(current_thread_info()->flags & _TIF_WORK_MASK))
+                        set_cr(cr_no_alignment);
+        }
 
         return 0;
 }