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Subject[patch 16/21] parisc: disable UP-optimized flush_tlb_mm
2.6.27-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Kyle McMartin <kyle@infradead.org>

commit 5289f46b9de04bde181d833d48df9671b69c4b08 upstream.

flush_tlb_mm's "optimized" uniprocessor case of allocating a new
context for userspace is exposing a race where we can suddely return
to a syscall with the protection id and space id out of sync, trapping
on the next userspace access.

Debugged-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Tested-by: Helge Deller <deller@gmx.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
include/asm-parisc/tlbflush.h | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/include/asm-parisc/tlbflush.h
+++ b/include/asm-parisc/tlbflush.h
@@ -44,9 +44,12 @@ static inline void flush_tlb_mm(struct m
{
BUG_ON(mm == &init_mm); /* Should never happen */

-#ifdef CONFIG_SMP
+#if 1 || defined(CONFIG_SMP)
flush_tlb_all();
#else
+ /* FIXME: currently broken, causing space id and protection ids
+ * to go out of sync, resulting in faults on userspace accesses.
+ */
if (mm) {
if (mm->context != 0)
free_sid(mm->context);


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