X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=include%2Fasm-um%2Fmmu_context.h;h=9a0e48eb542e019d5e259f3972550649bb1e46a8;hb=932355797530f5bd4e1355a2c384e9f3ccc3dcbc;hp=095bb627b96a1d52be4cc1291f48c308449f65a1;hpb=5d2a22079c825669d91a3a200332f1053b4b61b0;p=linux-2.6

diff --git a/include/asm-um/mmu_context.h b/include/asm-um/mmu_context.h
index 095bb627b9..9a0e48eb54 100644
--- a/include/asm-um/mmu_context.h
+++ b/include/asm-um/mmu_context.h
@@ -20,8 +20,17 @@ extern void force_flush_all(void);
 
 static inline void activate_mm(struct mm_struct *old, struct mm_struct *new)
 {
-	if (old != new)
-		force_flush_all();
+	/*
+	 * 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))
+		CHOOSE_MODE(force_flush_all(),
+			    switch_mm_skas(&new->context.skas.id));
 }
 
 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,