powerpc/mm/radix: Use mm->task_size for boundary checking instead of addr_limit

We don't init addr_limit correctly for 32 bit applications. So default to using
mm->task_size for boundary condition checking. We use addr_limit to only control
free space search. This makes sure that we do the right thing with 32 bit
applications.

We should consolidate the usage of TASK_SIZE/mm->task_size and
mm->context.addr_limit later.

This partially reverts commit fbfef9027c2a7ad (powerpc/mm: Switch some
TASK_SIZE checks to use mm_context addr_limit).

Fixes: fbfef9027c2a ("powerpc/mm: Switch some TASK_SIZE checks to use mm_context addr_limit")
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c
index 251b6bae..ade66c3 100644
--- a/arch/powerpc/mm/slice.c
+++ b/arch/powerpc/mm/slice.c
@@ -292,8 +292,8 @@ static unsigned long slice_find_area_bottomup(struct mm_struct *mm,
 		 * Check if we need to reduce the range, or if we can
 		 * extend it to cover the next available slice.
 		 */
-		if (addr >= mm->context.addr_limit)
-			addr = mm->context.addr_limit;
+		if (addr >= high_limit)
+			addr = high_limit;
 		else if (slice_scan_available(addr, available, 1, &next_end)) {
 			addr = next_end;
 			goto next_slice;