powerpc/mm: Fix broken MMU PID stealing on !SMP

The recent rework of the MMU PID handling for non-hash CPUs has a
subtle bug in the !SMP "optimized" variant of the PID stealing
function.  It clears the PID in the mm context before it calls
local_flush_tlb_mm(). However, the later will not flush anything
if the PID in the context is clear...

Signed-off-by: Hideo Saito <hsaito.ppc@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/mm/mmu_context_nohash.c b/arch/powerpc/mm/mmu_context_nohash.c
index a70e311bd457d83991895b2a519411f9ead6499d..030d0005b4d2c0682ca1adfd988b52000e73b7f2 100644 (file)
--- a/arch/powerpc/mm/mmu_context_nohash.c
+++ b/arch/powerpc/mm/mmu_context_nohash.c
@@ -127,12 +127,12 @@ static unsigned int steal_context_up(unsigned int id)
 
        pr_debug("[%d] steal context %d from mm @%p\n", cpu, id, mm);
 
-       /* Mark this mm has having no context anymore */
-       mm->context.id = MMU_NO_CONTEXT;
-
        /* Flush the TLB for that context */
        local_flush_tlb_mm(mm);
 
+       /* Mark this mm has having no context anymore */
+       mm->context.id = MMU_NO_CONTEXT;
+
        /* XXX This clear should ultimately be part of local_flush_tlb_mm */
        __clear_bit(id, stale_map[cpu]);