x86/dumpstack: Avoid uninitlized variable

In some configurations, 'partial' does not get initialized, as shown by
this gcc-8 warning:

arch/x86/kernel/dumpstack.c: In function 'show_trace_log_lvl':
arch/x86/kernel/dumpstack.c:156:4: error: 'partial' may be used uninitialized in this function [-Werror=maybe-uninitialized]
    show_regs_if_on_stack(&stack_info, regs, partial);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This initializes it to false, to get the previous behavior in this case.

Fixes: a9cdbe7 ("x86/dumpstack: Fix partial register dumps")
Signed-off-by: Arnd Bergmann <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Nicolas Pitre <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

Author: arndb

arch/x86/kernel/dumpstack.c

@@ -109,7 +109,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
 	struct stack_info stack_info = {0};
 	unsigned long visit_mask = 0;
 	int graph_idx = 0;
-	bool partial;
+	bool partial = false;
 
 	printk("%sCall Trace:\n", log_lvl);