[PATCH] uml-v2.6.12-bcrl-fix-tlb.diff

[Benjamin LaHaise <bcrl@kvack.org>]

Hello all,

This patch fixes a fairly serious tlb flushing bug that makes aio use under 
uml very unreliable -- SEGVs, Oops and panic()s occur as a result of stale 
tlb entires being used by uml when aio switches mms due to the fact that 
uml does not implement the activate_mm() hook.  This patch introduces a 
simple but correct approach (read: hammer) for implementing activate_mm() 
in uml by doing a force_flush_all() if the new mm is different from old.
With this patch in place, uml is able to succeed at the aio test case that 
was randomly faulting for me before.

		-ben

diff -purN 60_pipe_aio/include/asm-um/mmu_context.h test.diff/include/asm-um/mmu_context.h
--- 60_pipe_aio/include/asm-um/mmu_context.h	2004-12-24 16:34:57.000000000 -0500
+++ test.diff/include/asm-um/mmu_context.h	2005-07-05 14:38:34.569235552 -0400
@@ -14,8 +14,12 @@
 
 #define deactivate_mm(tsk,mm)	do { } while (0)
 
+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();
 }
 
 extern void switch_mm_skas(int mm_fd);
-
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