[PATCH v2 5/7] alpha: fix the local TLB invalidate in the UP flush_tlb_page()

[Magnus Lindholm <linmag7@gmail.com>]

The uniprocessor flush_tlb_page() in asm/tlbflush.h has the same wrong
test as the SMP one: a targeted tbi() reaches an mm's translations only
when a thread of that mm is current, but the gate is
current->active_mm.

Test current->mm instead. arch/alpha/kernel/smp.c is not built with
CONFIG_SMP=n, so this is how the same defect reaches a uniprocessor,
where the flusher kworker necessarily shares the only CPU with the
writer.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Magnus Lindholm <linmag7@gmail.com>
---
 arch/alpha/include/asm/tlbflush.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/alpha/include/asm/tlbflush.h b/arch/alpha/include/asm/tlbflush.h
index 0c8529997f54..9ae1902faf8e 100644
--- a/arch/alpha/include/asm/tlbflush.h
+++ b/arch/alpha/include/asm/tlbflush.h
@@ -87,7 +87,8 @@ flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
 {
 	struct mm_struct *mm = vma->vm_mm;
 
-	if (mm == current->active_mm)
+	/* A targeted tbi() needs a thread of MM to be current.  */
+	if (mm == current->mm)
 		flush_tlb_current_page(mm, vma, addr);
 	else
 		flush_tlb_other(mm);
-- 
2.53.0