Merge master.kernel.org:/home/rmk/linux-2.6-serial

[karo-tx-linux.git] / include / asm-um / mmu_context.h

diff --git a/include/asm-um/mmu_context.h b/include/asm-um/mmu_context.h
index 095bb627b96a1d52be4cc1291f48c308449f65a1..2edb4f1f789cdb96e0208da409622db6f1eaa70b 100644 (file)
--- a/include/asm-um/mmu_context.h
+++ b/include/asm-um/mmu_context.h
@@ -20,7 +20,15 @@ extern void force_flush_all(void);
 
 static inline void activate_mm(struct mm_struct *old, struct mm_struct *new)
 {
-       if (old != new)
+       /*
+        * This is called by fs/exec.c and fs/aio.c. In the first case, for an
+        * exec, we don't need to do anything as we're called from userspace
+        * and thus going to use a new host PID. In the second, we're called
+        * from a kernel thread, and thus need to go doing the mmap's on the
+        * host. Since they're very expensive, we want to avoid that as far as
+        * possible.
+        */
+       if (old != new && (current->flags & PF_BORROWED_MM))
                force_flush_all();
 }