[PATCH] Fix a PDA warning uncovered by the new type checking

Fix
linux/arch/x86_64/kernel/process.c: In function __switch_to:
linux/arch/x86_64/kernel/process.c:626: warning: assignment makes integer from pointer without a cast
Signed-off-by: Andi Kleen <ak@suse.de>

arch/x86_64/kernel/process.c

@@ -624,7 +624,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 	   And the AMD workaround requires it to be after DS reload. */
 	unlazy_fpu(prev_p);
 	write_pda(kernelstack,
-		  task_stack_page(next_p) + THREAD_SIZE - PDA_STACKOFFSET);
+	(unsigned long)task_stack_page(next_p) + THREAD_SIZE - PDA_STACKOFFSET);
 #ifdef CONFIG_CC_STACKPROTECTOR
 	write_pda(stack_canary, next_p->stack_canary);
 	/*